1 | /* |
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2 | Bullet Continuous Collision Detection and Physics Library |
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3 | btConeTwistConstraint is Copyright (c) 2007 Starbreeze Studios |
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4 | |
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5 | This software is provided 'as-is', without any express or implied warranty. |
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6 | In no event will the authors be held liable for any damages arising from the use of this software. |
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7 | Permission is granted to anyone to use this software for any purpose, |
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8 | including commercial applications, and to alter it and redistribute it freely, |
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9 | subject to the following restrictions: |
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10 | |
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11 | 1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required. |
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12 | 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software. |
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13 | 3. This notice may not be removed or altered from any source distribution. |
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14 | |
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15 | Written by: Marcus Hennix |
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16 | */ |
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17 | |
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18 | |
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19 | #include "btConeTwistConstraint.h" |
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20 | #include "BulletDynamics/Dynamics/btRigidBody.h" |
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21 | #include "LinearMath/btTransformUtil.h" |
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22 | #include "LinearMath/btMinMax.h" |
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23 | #include <new> |
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24 | |
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25 | |
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26 | |
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27 | //#define CONETWIST_USE_OBSOLETE_SOLVER true |
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28 | #define CONETWIST_USE_OBSOLETE_SOLVER false |
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29 | #define CONETWIST_DEF_FIX_THRESH btScalar(.05f) |
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30 | |
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31 | |
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32 | SIMD_FORCE_INLINE btScalar computeAngularImpulseDenominator(const btVector3& axis, const btMatrix3x3& invInertiaWorld) |
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33 | { |
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34 | btVector3 vec = axis * invInertiaWorld; |
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35 | return axis.dot(vec); |
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36 | } |
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37 | |
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38 | |
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39 | |
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40 | |
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41 | btConeTwistConstraint::btConeTwistConstraint(btRigidBody& rbA,btRigidBody& rbB, |
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42 | const btTransform& rbAFrame,const btTransform& rbBFrame) |
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43 | :btTypedConstraint(CONETWIST_CONSTRAINT_TYPE, rbA,rbB),m_rbAFrame(rbAFrame),m_rbBFrame(rbBFrame), |
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44 | m_angularOnly(false), |
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45 | m_useSolveConstraintObsolete(CONETWIST_USE_OBSOLETE_SOLVER) |
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46 | { |
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47 | init(); |
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48 | } |
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49 | |
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50 | btConeTwistConstraint::btConeTwistConstraint(btRigidBody& rbA,const btTransform& rbAFrame) |
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51 | :btTypedConstraint(CONETWIST_CONSTRAINT_TYPE,rbA),m_rbAFrame(rbAFrame), |
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52 | m_angularOnly(false), |
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53 | m_useSolveConstraintObsolete(CONETWIST_USE_OBSOLETE_SOLVER) |
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54 | { |
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55 | m_rbBFrame = m_rbAFrame; |
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56 | init(); |
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57 | } |
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58 | |
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59 | |
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60 | void btConeTwistConstraint::init() |
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61 | { |
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62 | m_angularOnly = false; |
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63 | m_solveTwistLimit = false; |
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64 | m_solveSwingLimit = false; |
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65 | m_bMotorEnabled = false; |
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66 | m_maxMotorImpulse = btScalar(-1); |
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67 | |
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68 | setLimit(btScalar(BT_LARGE_FLOAT), btScalar(BT_LARGE_FLOAT), btScalar(BT_LARGE_FLOAT)); |
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69 | m_damping = btScalar(0.01); |
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70 | m_fixThresh = CONETWIST_DEF_FIX_THRESH; |
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71 | m_flags = 0; |
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72 | m_linCFM = btScalar(0.f); |
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73 | m_linERP = btScalar(0.7f); |
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74 | m_angCFM = btScalar(0.f); |
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75 | } |
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76 | |
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77 | |
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78 | void btConeTwistConstraint::getInfo1 (btConstraintInfo1* info) |
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79 | { |
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80 | if (m_useSolveConstraintObsolete) |
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81 | { |
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82 | info->m_numConstraintRows = 0; |
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83 | info->nub = 0; |
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84 | } |
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85 | else |
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86 | { |
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87 | info->m_numConstraintRows = 3; |
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88 | info->nub = 3; |
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89 | calcAngleInfo2(m_rbA.getCenterOfMassTransform(),m_rbB.getCenterOfMassTransform(),m_rbA.getInvInertiaTensorWorld(),m_rbB.getInvInertiaTensorWorld()); |
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90 | if(m_solveSwingLimit) |
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91 | { |
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92 | info->m_numConstraintRows++; |
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93 | info->nub--; |
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94 | if((m_swingSpan1 < m_fixThresh) && (m_swingSpan2 < m_fixThresh)) |
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95 | { |
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96 | info->m_numConstraintRows++; |
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97 | info->nub--; |
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98 | } |
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99 | } |
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100 | if(m_solveTwistLimit) |
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101 | { |
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102 | info->m_numConstraintRows++; |
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103 | info->nub--; |
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104 | } |
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105 | } |
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106 | } |
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107 | |
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108 | void btConeTwistConstraint::getInfo1NonVirtual (btConstraintInfo1* info) |
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109 | { |
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110 | //always reserve 6 rows: object transform is not available on SPU |
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111 | info->m_numConstraintRows = 6; |
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112 | info->nub = 0; |
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113 | |
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114 | } |
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115 | |
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116 | |
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117 | void btConeTwistConstraint::getInfo2 (btConstraintInfo2* info) |
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118 | { |
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119 | getInfo2NonVirtual(info,m_rbA.getCenterOfMassTransform(),m_rbB.getCenterOfMassTransform(),m_rbA.getInvInertiaTensorWorld(),m_rbB.getInvInertiaTensorWorld()); |
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120 | } |
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121 | |
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122 | void btConeTwistConstraint::getInfo2NonVirtual (btConstraintInfo2* info,const btTransform& transA,const btTransform& transB,const btMatrix3x3& invInertiaWorldA,const btMatrix3x3& invInertiaWorldB) |
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123 | { |
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124 | calcAngleInfo2(transA,transB,invInertiaWorldA,invInertiaWorldB); |
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125 | |
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126 | btAssert(!m_useSolveConstraintObsolete); |
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127 | // set jacobian |
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128 | info->m_J1linearAxis[0] = 1; |
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129 | info->m_J1linearAxis[info->rowskip+1] = 1; |
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130 | info->m_J1linearAxis[2*info->rowskip+2] = 1; |
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131 | btVector3 a1 = transA.getBasis() * m_rbAFrame.getOrigin(); |
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132 | { |
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133 | btVector3* angular0 = (btVector3*)(info->m_J1angularAxis); |
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134 | btVector3* angular1 = (btVector3*)(info->m_J1angularAxis+info->rowskip); |
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135 | btVector3* angular2 = (btVector3*)(info->m_J1angularAxis+2*info->rowskip); |
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136 | btVector3 a1neg = -a1; |
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137 | a1neg.getSkewSymmetricMatrix(angular0,angular1,angular2); |
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138 | } |
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139 | btVector3 a2 = transB.getBasis() * m_rbBFrame.getOrigin(); |
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140 | { |
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141 | btVector3* angular0 = (btVector3*)(info->m_J2angularAxis); |
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142 | btVector3* angular1 = (btVector3*)(info->m_J2angularAxis+info->rowskip); |
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143 | btVector3* angular2 = (btVector3*)(info->m_J2angularAxis+2*info->rowskip); |
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144 | a2.getSkewSymmetricMatrix(angular0,angular1,angular2); |
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145 | } |
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146 | // set right hand side |
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147 | btScalar linERP = (m_flags & BT_CONETWIST_FLAGS_LIN_ERP) ? m_linERP : info->erp; |
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148 | btScalar k = info->fps * linERP; |
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149 | int j; |
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150 | for (j=0; j<3; j++) |
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151 | { |
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152 | info->m_constraintError[j*info->rowskip] = k * (a2[j] + transB.getOrigin()[j] - a1[j] - transA.getOrigin()[j]); |
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153 | info->m_lowerLimit[j*info->rowskip] = -SIMD_INFINITY; |
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154 | info->m_upperLimit[j*info->rowskip] = SIMD_INFINITY; |
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155 | if(m_flags & BT_CONETWIST_FLAGS_LIN_CFM) |
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156 | { |
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157 | info->cfm[j*info->rowskip] = m_linCFM; |
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158 | } |
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159 | } |
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160 | int row = 3; |
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161 | int srow = row * info->rowskip; |
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162 | btVector3 ax1; |
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163 | // angular limits |
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164 | if(m_solveSwingLimit) |
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165 | { |
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166 | btScalar *J1 = info->m_J1angularAxis; |
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167 | btScalar *J2 = info->m_J2angularAxis; |
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168 | if((m_swingSpan1 < m_fixThresh) && (m_swingSpan2 < m_fixThresh)) |
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169 | { |
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170 | btTransform trA = transA*m_rbAFrame; |
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171 | btVector3 p = trA.getBasis().getColumn(1); |
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172 | btVector3 q = trA.getBasis().getColumn(2); |
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173 | int srow1 = srow + info->rowskip; |
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174 | J1[srow+0] = p[0]; |
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175 | J1[srow+1] = p[1]; |
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176 | J1[srow+2] = p[2]; |
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177 | J1[srow1+0] = q[0]; |
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178 | J1[srow1+1] = q[1]; |
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179 | J1[srow1+2] = q[2]; |
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180 | J2[srow+0] = -p[0]; |
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181 | J2[srow+1] = -p[1]; |
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182 | J2[srow+2] = -p[2]; |
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183 | J2[srow1+0] = -q[0]; |
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184 | J2[srow1+1] = -q[1]; |
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185 | J2[srow1+2] = -q[2]; |
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186 | btScalar fact = info->fps * m_relaxationFactor; |
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187 | info->m_constraintError[srow] = fact * m_swingAxis.dot(p); |
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188 | info->m_constraintError[srow1] = fact * m_swingAxis.dot(q); |
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189 | info->m_lowerLimit[srow] = -SIMD_INFINITY; |
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190 | info->m_upperLimit[srow] = SIMD_INFINITY; |
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191 | info->m_lowerLimit[srow1] = -SIMD_INFINITY; |
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192 | info->m_upperLimit[srow1] = SIMD_INFINITY; |
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193 | srow = srow1 + info->rowskip; |
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194 | } |
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195 | else |
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196 | { |
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197 | ax1 = m_swingAxis * m_relaxationFactor * m_relaxationFactor; |
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198 | J1[srow+0] = ax1[0]; |
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199 | J1[srow+1] = ax1[1]; |
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200 | J1[srow+2] = ax1[2]; |
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201 | J2[srow+0] = -ax1[0]; |
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202 | J2[srow+1] = -ax1[1]; |
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203 | J2[srow+2] = -ax1[2]; |
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204 | btScalar k = info->fps * m_biasFactor; |
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205 | |
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206 | info->m_constraintError[srow] = k * m_swingCorrection; |
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207 | if(m_flags & BT_CONETWIST_FLAGS_ANG_CFM) |
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208 | { |
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209 | info->cfm[srow] = m_angCFM; |
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210 | } |
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211 | // m_swingCorrection is always positive or 0 |
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212 | info->m_lowerLimit[srow] = 0; |
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213 | info->m_upperLimit[srow] = SIMD_INFINITY; |
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214 | srow += info->rowskip; |
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215 | } |
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216 | } |
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217 | if(m_solveTwistLimit) |
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218 | { |
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219 | ax1 = m_twistAxis * m_relaxationFactor * m_relaxationFactor; |
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220 | btScalar *J1 = info->m_J1angularAxis; |
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221 | btScalar *J2 = info->m_J2angularAxis; |
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222 | J1[srow+0] = ax1[0]; |
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223 | J1[srow+1] = ax1[1]; |
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224 | J1[srow+2] = ax1[2]; |
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225 | J2[srow+0] = -ax1[0]; |
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226 | J2[srow+1] = -ax1[1]; |
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227 | J2[srow+2] = -ax1[2]; |
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228 | btScalar k = info->fps * m_biasFactor; |
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229 | info->m_constraintError[srow] = k * m_twistCorrection; |
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230 | if(m_flags & BT_CONETWIST_FLAGS_ANG_CFM) |
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231 | { |
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232 | info->cfm[srow] = m_angCFM; |
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233 | } |
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234 | if(m_twistSpan > 0.0f) |
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235 | { |
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236 | |
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237 | if(m_twistCorrection > 0.0f) |
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238 | { |
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239 | info->m_lowerLimit[srow] = 0; |
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240 | info->m_upperLimit[srow] = SIMD_INFINITY; |
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241 | } |
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242 | else |
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243 | { |
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244 | info->m_lowerLimit[srow] = -SIMD_INFINITY; |
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245 | info->m_upperLimit[srow] = 0; |
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246 | } |
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247 | } |
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248 | else |
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249 | { |
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250 | info->m_lowerLimit[srow] = -SIMD_INFINITY; |
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251 | info->m_upperLimit[srow] = SIMD_INFINITY; |
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252 | } |
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253 | srow += info->rowskip; |
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254 | } |
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255 | } |
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256 | |
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257 | |
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258 | |
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259 | void btConeTwistConstraint::buildJacobian() |
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260 | { |
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261 | if (m_useSolveConstraintObsolete) |
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262 | { |
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263 | m_appliedImpulse = btScalar(0.); |
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264 | m_accTwistLimitImpulse = btScalar(0.); |
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265 | m_accSwingLimitImpulse = btScalar(0.); |
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266 | m_accMotorImpulse = btVector3(0.,0.,0.); |
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267 | |
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268 | if (!m_angularOnly) |
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269 | { |
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270 | btVector3 pivotAInW = m_rbA.getCenterOfMassTransform()*m_rbAFrame.getOrigin(); |
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271 | btVector3 pivotBInW = m_rbB.getCenterOfMassTransform()*m_rbBFrame.getOrigin(); |
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272 | btVector3 relPos = pivotBInW - pivotAInW; |
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273 | |
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274 | btVector3 normal[3]; |
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275 | if (relPos.length2() > SIMD_EPSILON) |
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276 | { |
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277 | normal[0] = relPos.normalized(); |
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278 | } |
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279 | else |
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280 | { |
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281 | normal[0].setValue(btScalar(1.0),0,0); |
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282 | } |
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283 | |
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284 | btPlaneSpace1(normal[0], normal[1], normal[2]); |
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285 | |
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286 | for (int i=0;i<3;i++) |
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287 | { |
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288 | new (&m_jac[i]) btJacobianEntry( |
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289 | m_rbA.getCenterOfMassTransform().getBasis().transpose(), |
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290 | m_rbB.getCenterOfMassTransform().getBasis().transpose(), |
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291 | pivotAInW - m_rbA.getCenterOfMassPosition(), |
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292 | pivotBInW - m_rbB.getCenterOfMassPosition(), |
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293 | normal[i], |
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294 | m_rbA.getInvInertiaDiagLocal(), |
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295 | m_rbA.getInvMass(), |
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296 | m_rbB.getInvInertiaDiagLocal(), |
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297 | m_rbB.getInvMass()); |
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298 | } |
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299 | } |
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300 | |
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301 | calcAngleInfo2(m_rbA.getCenterOfMassTransform(),m_rbB.getCenterOfMassTransform(),m_rbA.getInvInertiaTensorWorld(),m_rbB.getInvInertiaTensorWorld()); |
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302 | } |
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303 | } |
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304 | |
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305 | |
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306 | |
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307 | void btConeTwistConstraint::solveConstraintObsolete(btRigidBody& bodyA,btRigidBody& bodyB,btScalar timeStep) |
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308 | { |
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309 | #ifndef __SPU__ |
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310 | if (m_useSolveConstraintObsolete) |
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311 | { |
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312 | btVector3 pivotAInW = m_rbA.getCenterOfMassTransform()*m_rbAFrame.getOrigin(); |
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313 | btVector3 pivotBInW = m_rbB.getCenterOfMassTransform()*m_rbBFrame.getOrigin(); |
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314 | |
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315 | btScalar tau = btScalar(0.3); |
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316 | |
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317 | //linear part |
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318 | if (!m_angularOnly) |
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319 | { |
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320 | btVector3 rel_pos1 = pivotAInW - m_rbA.getCenterOfMassPosition(); |
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321 | btVector3 rel_pos2 = pivotBInW - m_rbB.getCenterOfMassPosition(); |
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322 | |
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323 | btVector3 vel1; |
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324 | bodyA.internalGetVelocityInLocalPointObsolete(rel_pos1,vel1); |
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325 | btVector3 vel2; |
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326 | bodyB.internalGetVelocityInLocalPointObsolete(rel_pos2,vel2); |
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327 | btVector3 vel = vel1 - vel2; |
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328 | |
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329 | for (int i=0;i<3;i++) |
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330 | { |
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331 | const btVector3& normal = m_jac[i].m_linearJointAxis; |
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332 | btScalar jacDiagABInv = btScalar(1.) / m_jac[i].getDiagonal(); |
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333 | |
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334 | btScalar rel_vel; |
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335 | rel_vel = normal.dot(vel); |
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336 | //positional error (zeroth order error) |
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337 | btScalar depth = -(pivotAInW - pivotBInW).dot(normal); //this is the error projected on the normal |
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338 | btScalar impulse = depth*tau/timeStep * jacDiagABInv - rel_vel * jacDiagABInv; |
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339 | m_appliedImpulse += impulse; |
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340 | |
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341 | btVector3 ftorqueAxis1 = rel_pos1.cross(normal); |
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342 | btVector3 ftorqueAxis2 = rel_pos2.cross(normal); |
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343 | bodyA.internalApplyImpulse(normal*m_rbA.getInvMass(), m_rbA.getInvInertiaTensorWorld()*ftorqueAxis1,impulse); |
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344 | bodyB.internalApplyImpulse(normal*m_rbB.getInvMass(), m_rbB.getInvInertiaTensorWorld()*ftorqueAxis2,-impulse); |
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345 | |
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346 | } |
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347 | } |
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348 | |
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349 | // apply motor |
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350 | if (m_bMotorEnabled) |
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351 | { |
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352 | // compute current and predicted transforms |
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353 | btTransform trACur = m_rbA.getCenterOfMassTransform(); |
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354 | btTransform trBCur = m_rbB.getCenterOfMassTransform(); |
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355 | btVector3 omegaA; bodyA.internalGetAngularVelocity(omegaA); |
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356 | btVector3 omegaB; bodyB.internalGetAngularVelocity(omegaB); |
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357 | btTransform trAPred; trAPred.setIdentity(); |
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358 | btVector3 zerovec(0,0,0); |
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359 | btTransformUtil::integrateTransform( |
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360 | trACur, zerovec, omegaA, timeStep, trAPred); |
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361 | btTransform trBPred; trBPred.setIdentity(); |
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362 | btTransformUtil::integrateTransform( |
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363 | trBCur, zerovec, omegaB, timeStep, trBPred); |
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364 | |
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365 | // compute desired transforms in world |
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366 | btTransform trPose(m_qTarget); |
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367 | btTransform trABDes = m_rbBFrame * trPose * m_rbAFrame.inverse(); |
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368 | btTransform trADes = trBPred * trABDes; |
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369 | btTransform trBDes = trAPred * trABDes.inverse(); |
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370 | |
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371 | // compute desired omegas in world |
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372 | btVector3 omegaADes, omegaBDes; |
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373 | |
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374 | btTransformUtil::calculateVelocity(trACur, trADes, timeStep, zerovec, omegaADes); |
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375 | btTransformUtil::calculateVelocity(trBCur, trBDes, timeStep, zerovec, omegaBDes); |
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376 | |
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377 | // compute delta omegas |
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378 | btVector3 dOmegaA = omegaADes - omegaA; |
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379 | btVector3 dOmegaB = omegaBDes - omegaB; |
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380 | |
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381 | // compute weighted avg axis of dOmega (weighting based on inertias) |
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382 | btVector3 axisA, axisB; |
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383 | btScalar kAxisAInv = 0, kAxisBInv = 0; |
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384 | |
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385 | if (dOmegaA.length2() > SIMD_EPSILON) |
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386 | { |
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387 | axisA = dOmegaA.normalized(); |
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388 | kAxisAInv = getRigidBodyA().computeAngularImpulseDenominator(axisA); |
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389 | } |
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390 | |
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391 | if (dOmegaB.length2() > SIMD_EPSILON) |
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392 | { |
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393 | axisB = dOmegaB.normalized(); |
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394 | kAxisBInv = getRigidBodyB().computeAngularImpulseDenominator(axisB); |
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395 | } |
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396 | |
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397 | btVector3 avgAxis = kAxisAInv * axisA + kAxisBInv * axisB; |
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398 | |
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399 | static bool bDoTorque = true; |
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400 | if (bDoTorque && avgAxis.length2() > SIMD_EPSILON) |
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401 | { |
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402 | avgAxis.normalize(); |
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403 | kAxisAInv = getRigidBodyA().computeAngularImpulseDenominator(avgAxis); |
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404 | kAxisBInv = getRigidBodyB().computeAngularImpulseDenominator(avgAxis); |
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405 | btScalar kInvCombined = kAxisAInv + kAxisBInv; |
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406 | |
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407 | btVector3 impulse = (kAxisAInv * dOmegaA - kAxisBInv * dOmegaB) / |
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408 | (kInvCombined * kInvCombined); |
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409 | |
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410 | if (m_maxMotorImpulse >= 0) |
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411 | { |
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412 | btScalar fMaxImpulse = m_maxMotorImpulse; |
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413 | if (m_bNormalizedMotorStrength) |
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414 | fMaxImpulse = fMaxImpulse/kAxisAInv; |
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415 | |
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416 | btVector3 newUnclampedAccImpulse = m_accMotorImpulse + impulse; |
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417 | btScalar newUnclampedMag = newUnclampedAccImpulse.length(); |
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418 | if (newUnclampedMag > fMaxImpulse) |
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419 | { |
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420 | newUnclampedAccImpulse.normalize(); |
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421 | newUnclampedAccImpulse *= fMaxImpulse; |
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422 | impulse = newUnclampedAccImpulse - m_accMotorImpulse; |
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423 | } |
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424 | m_accMotorImpulse += impulse; |
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425 | } |
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426 | |
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427 | btScalar impulseMag = impulse.length(); |
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428 | btVector3 impulseAxis = impulse / impulseMag; |
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429 | |
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430 | bodyA.internalApplyImpulse(btVector3(0,0,0), m_rbA.getInvInertiaTensorWorld()*impulseAxis, impulseMag); |
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431 | bodyB.internalApplyImpulse(btVector3(0,0,0), m_rbB.getInvInertiaTensorWorld()*impulseAxis, -impulseMag); |
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432 | |
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433 | } |
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434 | } |
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435 | else if (m_damping > SIMD_EPSILON) // no motor: do a little damping |
---|
436 | { |
---|
437 | btVector3 angVelA; bodyA.internalGetAngularVelocity(angVelA); |
---|
438 | btVector3 angVelB; bodyB.internalGetAngularVelocity(angVelB); |
---|
439 | btVector3 relVel = angVelB - angVelA; |
---|
440 | if (relVel.length2() > SIMD_EPSILON) |
---|
441 | { |
---|
442 | btVector3 relVelAxis = relVel.normalized(); |
---|
443 | btScalar m_kDamping = btScalar(1.) / |
---|
444 | (getRigidBodyA().computeAngularImpulseDenominator(relVelAxis) + |
---|
445 | getRigidBodyB().computeAngularImpulseDenominator(relVelAxis)); |
---|
446 | btVector3 impulse = m_damping * m_kDamping * relVel; |
---|
447 | |
---|
448 | btScalar impulseMag = impulse.length(); |
---|
449 | btVector3 impulseAxis = impulse / impulseMag; |
---|
450 | bodyA.internalApplyImpulse(btVector3(0,0,0), m_rbA.getInvInertiaTensorWorld()*impulseAxis, impulseMag); |
---|
451 | bodyB.internalApplyImpulse(btVector3(0,0,0), m_rbB.getInvInertiaTensorWorld()*impulseAxis, -impulseMag); |
---|
452 | } |
---|
453 | } |
---|
454 | |
---|
455 | // joint limits |
---|
456 | { |
---|
457 | ///solve angular part |
---|
458 | btVector3 angVelA; |
---|
459 | bodyA.internalGetAngularVelocity(angVelA); |
---|
460 | btVector3 angVelB; |
---|
461 | bodyB.internalGetAngularVelocity(angVelB); |
---|
462 | |
---|
463 | // solve swing limit |
---|
464 | if (m_solveSwingLimit) |
---|
465 | { |
---|
466 | btScalar amplitude = m_swingLimitRatio * m_swingCorrection*m_biasFactor/timeStep; |
---|
467 | btScalar relSwingVel = (angVelB - angVelA).dot(m_swingAxis); |
---|
468 | if (relSwingVel > 0) |
---|
469 | amplitude += m_swingLimitRatio * relSwingVel * m_relaxationFactor; |
---|
470 | btScalar impulseMag = amplitude * m_kSwing; |
---|
471 | |
---|
472 | // Clamp the accumulated impulse |
---|
473 | btScalar temp = m_accSwingLimitImpulse; |
---|
474 | m_accSwingLimitImpulse = btMax(m_accSwingLimitImpulse + impulseMag, btScalar(0.0) ); |
---|
475 | impulseMag = m_accSwingLimitImpulse - temp; |
---|
476 | |
---|
477 | btVector3 impulse = m_swingAxis * impulseMag; |
---|
478 | |
---|
479 | // don't let cone response affect twist |
---|
480 | // (this can happen since body A's twist doesn't match body B's AND we use an elliptical cone limit) |
---|
481 | { |
---|
482 | btVector3 impulseTwistCouple = impulse.dot(m_twistAxisA) * m_twistAxisA; |
---|
483 | btVector3 impulseNoTwistCouple = impulse - impulseTwistCouple; |
---|
484 | impulse = impulseNoTwistCouple; |
---|
485 | } |
---|
486 | |
---|
487 | impulseMag = impulse.length(); |
---|
488 | btVector3 noTwistSwingAxis = impulse / impulseMag; |
---|
489 | |
---|
490 | bodyA.internalApplyImpulse(btVector3(0,0,0), m_rbA.getInvInertiaTensorWorld()*noTwistSwingAxis, impulseMag); |
---|
491 | bodyB.internalApplyImpulse(btVector3(0,0,0), m_rbB.getInvInertiaTensorWorld()*noTwistSwingAxis, -impulseMag); |
---|
492 | } |
---|
493 | |
---|
494 | |
---|
495 | // solve twist limit |
---|
496 | if (m_solveTwistLimit) |
---|
497 | { |
---|
498 | btScalar amplitude = m_twistLimitRatio * m_twistCorrection*m_biasFactor/timeStep; |
---|
499 | btScalar relTwistVel = (angVelB - angVelA).dot( m_twistAxis ); |
---|
500 | if (relTwistVel > 0) // only damp when moving towards limit (m_twistAxis flipping is important) |
---|
501 | amplitude += m_twistLimitRatio * relTwistVel * m_relaxationFactor; |
---|
502 | btScalar impulseMag = amplitude * m_kTwist; |
---|
503 | |
---|
504 | // Clamp the accumulated impulse |
---|
505 | btScalar temp = m_accTwistLimitImpulse; |
---|
506 | m_accTwistLimitImpulse = btMax(m_accTwistLimitImpulse + impulseMag, btScalar(0.0) ); |
---|
507 | impulseMag = m_accTwistLimitImpulse - temp; |
---|
508 | |
---|
509 | btVector3 impulse = m_twistAxis * impulseMag; |
---|
510 | |
---|
511 | bodyA.internalApplyImpulse(btVector3(0,0,0), m_rbA.getInvInertiaTensorWorld()*m_twistAxis,impulseMag); |
---|
512 | bodyB.internalApplyImpulse(btVector3(0,0,0), m_rbB.getInvInertiaTensorWorld()*m_twistAxis,-impulseMag); |
---|
513 | } |
---|
514 | } |
---|
515 | } |
---|
516 | #else |
---|
517 | btAssert(0); |
---|
518 | #endif //__SPU__ |
---|
519 | } |
---|
520 | |
---|
521 | |
---|
522 | |
---|
523 | |
---|
524 | void btConeTwistConstraint::updateRHS(btScalar timeStep) |
---|
525 | { |
---|
526 | (void)timeStep; |
---|
527 | |
---|
528 | } |
---|
529 | |
---|
530 | |
---|
531 | #ifndef __SPU__ |
---|
532 | void btConeTwistConstraint::calcAngleInfo() |
---|
533 | { |
---|
534 | m_swingCorrection = btScalar(0.); |
---|
535 | m_twistLimitSign = btScalar(0.); |
---|
536 | m_solveTwistLimit = false; |
---|
537 | m_solveSwingLimit = false; |
---|
538 | |
---|
539 | btVector3 b1Axis1,b1Axis2,b1Axis3; |
---|
540 | btVector3 b2Axis1,b2Axis2; |
---|
541 | |
---|
542 | b1Axis1 = getRigidBodyA().getCenterOfMassTransform().getBasis() * this->m_rbAFrame.getBasis().getColumn(0); |
---|
543 | b2Axis1 = getRigidBodyB().getCenterOfMassTransform().getBasis() * this->m_rbBFrame.getBasis().getColumn(0); |
---|
544 | |
---|
545 | btScalar swing1=btScalar(0.),swing2 = btScalar(0.); |
---|
546 | |
---|
547 | btScalar swx=btScalar(0.),swy = btScalar(0.); |
---|
548 | btScalar thresh = btScalar(10.); |
---|
549 | btScalar fact; |
---|
550 | |
---|
551 | // Get Frame into world space |
---|
552 | if (m_swingSpan1 >= btScalar(0.05f)) |
---|
553 | { |
---|
554 | b1Axis2 = getRigidBodyA().getCenterOfMassTransform().getBasis() * this->m_rbAFrame.getBasis().getColumn(1); |
---|
555 | swx = b2Axis1.dot(b1Axis1); |
---|
556 | swy = b2Axis1.dot(b1Axis2); |
---|
557 | swing1 = btAtan2Fast(swy, swx); |
---|
558 | fact = (swy*swy + swx*swx) * thresh * thresh; |
---|
559 | fact = fact / (fact + btScalar(1.0)); |
---|
560 | swing1 *= fact; |
---|
561 | } |
---|
562 | |
---|
563 | if (m_swingSpan2 >= btScalar(0.05f)) |
---|
564 | { |
---|
565 | b1Axis3 = getRigidBodyA().getCenterOfMassTransform().getBasis() * this->m_rbAFrame.getBasis().getColumn(2); |
---|
566 | swx = b2Axis1.dot(b1Axis1); |
---|
567 | swy = b2Axis1.dot(b1Axis3); |
---|
568 | swing2 = btAtan2Fast(swy, swx); |
---|
569 | fact = (swy*swy + swx*swx) * thresh * thresh; |
---|
570 | fact = fact / (fact + btScalar(1.0)); |
---|
571 | swing2 *= fact; |
---|
572 | } |
---|
573 | |
---|
574 | btScalar RMaxAngle1Sq = 1.0f / (m_swingSpan1*m_swingSpan1); |
---|
575 | btScalar RMaxAngle2Sq = 1.0f / (m_swingSpan2*m_swingSpan2); |
---|
576 | btScalar EllipseAngle = btFabs(swing1*swing1)* RMaxAngle1Sq + btFabs(swing2*swing2) * RMaxAngle2Sq; |
---|
577 | |
---|
578 | if (EllipseAngle > 1.0f) |
---|
579 | { |
---|
580 | m_swingCorrection = EllipseAngle-1.0f; |
---|
581 | m_solveSwingLimit = true; |
---|
582 | // Calculate necessary axis & factors |
---|
583 | m_swingAxis = b2Axis1.cross(b1Axis2* b2Axis1.dot(b1Axis2) + b1Axis3* b2Axis1.dot(b1Axis3)); |
---|
584 | m_swingAxis.normalize(); |
---|
585 | btScalar swingAxisSign = (b2Axis1.dot(b1Axis1) >= 0.0f) ? 1.0f : -1.0f; |
---|
586 | m_swingAxis *= swingAxisSign; |
---|
587 | } |
---|
588 | |
---|
589 | // Twist limits |
---|
590 | if (m_twistSpan >= btScalar(0.)) |
---|
591 | { |
---|
592 | btVector3 b2Axis2 = getRigidBodyB().getCenterOfMassTransform().getBasis() * this->m_rbBFrame.getBasis().getColumn(1); |
---|
593 | btQuaternion rotationArc = shortestArcQuat(b2Axis1,b1Axis1); |
---|
594 | btVector3 TwistRef = quatRotate(rotationArc,b2Axis2); |
---|
595 | btScalar twist = btAtan2Fast( TwistRef.dot(b1Axis3), TwistRef.dot(b1Axis2) ); |
---|
596 | m_twistAngle = twist; |
---|
597 | |
---|
598 | // btScalar lockedFreeFactor = (m_twistSpan > btScalar(0.05f)) ? m_limitSoftness : btScalar(0.); |
---|
599 | btScalar lockedFreeFactor = (m_twistSpan > btScalar(0.05f)) ? btScalar(1.0f) : btScalar(0.); |
---|
600 | if (twist <= -m_twistSpan*lockedFreeFactor) |
---|
601 | { |
---|
602 | m_twistCorrection = -(twist + m_twistSpan); |
---|
603 | m_solveTwistLimit = true; |
---|
604 | m_twistAxis = (b2Axis1 + b1Axis1) * 0.5f; |
---|
605 | m_twistAxis.normalize(); |
---|
606 | m_twistAxis *= -1.0f; |
---|
607 | } |
---|
608 | else if (twist > m_twistSpan*lockedFreeFactor) |
---|
609 | { |
---|
610 | m_twistCorrection = (twist - m_twistSpan); |
---|
611 | m_solveTwistLimit = true; |
---|
612 | m_twistAxis = (b2Axis1 + b1Axis1) * 0.5f; |
---|
613 | m_twistAxis.normalize(); |
---|
614 | } |
---|
615 | } |
---|
616 | } |
---|
617 | #endif //__SPU__ |
---|
618 | |
---|
619 | static btVector3 vTwist(1,0,0); // twist axis in constraint's space |
---|
620 | |
---|
621 | |
---|
622 | |
---|
623 | void btConeTwistConstraint::calcAngleInfo2(const btTransform& transA, const btTransform& transB, const btMatrix3x3& invInertiaWorldA,const btMatrix3x3& invInertiaWorldB) |
---|
624 | { |
---|
625 | m_swingCorrection = btScalar(0.); |
---|
626 | m_twistLimitSign = btScalar(0.); |
---|
627 | m_solveTwistLimit = false; |
---|
628 | m_solveSwingLimit = false; |
---|
629 | // compute rotation of A wrt B (in constraint space) |
---|
630 | if (m_bMotorEnabled && (!m_useSolveConstraintObsolete)) |
---|
631 | { // it is assumed that setMotorTarget() was alredy called |
---|
632 | // and motor target m_qTarget is within constraint limits |
---|
633 | // TODO : split rotation to pure swing and pure twist |
---|
634 | // compute desired transforms in world |
---|
635 | btTransform trPose(m_qTarget); |
---|
636 | btTransform trA = transA * m_rbAFrame; |
---|
637 | btTransform trB = transB * m_rbBFrame; |
---|
638 | btTransform trDeltaAB = trB * trPose * trA.inverse(); |
---|
639 | btQuaternion qDeltaAB = trDeltaAB.getRotation(); |
---|
640 | btVector3 swingAxis = btVector3(qDeltaAB.x(), qDeltaAB.y(), qDeltaAB.z()); |
---|
641 | m_swingAxis = swingAxis; |
---|
642 | m_swingAxis.normalize(); |
---|
643 | m_swingCorrection = qDeltaAB.getAngle(); |
---|
644 | if(!btFuzzyZero(m_swingCorrection)) |
---|
645 | { |
---|
646 | m_solveSwingLimit = true; |
---|
647 | } |
---|
648 | return; |
---|
649 | } |
---|
650 | |
---|
651 | |
---|
652 | { |
---|
653 | // compute rotation of A wrt B (in constraint space) |
---|
654 | btQuaternion qA = transA.getRotation() * m_rbAFrame.getRotation(); |
---|
655 | btQuaternion qB = transB.getRotation() * m_rbBFrame.getRotation(); |
---|
656 | btQuaternion qAB = qB.inverse() * qA; |
---|
657 | // split rotation into cone and twist |
---|
658 | // (all this is done from B's perspective. Maybe I should be averaging axes...) |
---|
659 | btVector3 vConeNoTwist = quatRotate(qAB, vTwist); vConeNoTwist.normalize(); |
---|
660 | btQuaternion qABCone = shortestArcQuat(vTwist, vConeNoTwist); qABCone.normalize(); |
---|
661 | btQuaternion qABTwist = qABCone.inverse() * qAB; qABTwist.normalize(); |
---|
662 | |
---|
663 | if (m_swingSpan1 >= m_fixThresh && m_swingSpan2 >= m_fixThresh) |
---|
664 | { |
---|
665 | btScalar swingAngle, swingLimit = 0; btVector3 swingAxis; |
---|
666 | computeConeLimitInfo(qABCone, swingAngle, swingAxis, swingLimit); |
---|
667 | |
---|
668 | if (swingAngle > swingLimit * m_limitSoftness) |
---|
669 | { |
---|
670 | m_solveSwingLimit = true; |
---|
671 | |
---|
672 | // compute limit ratio: 0->1, where |
---|
673 | // 0 == beginning of soft limit |
---|
674 | // 1 == hard/real limit |
---|
675 | m_swingLimitRatio = 1.f; |
---|
676 | if (swingAngle < swingLimit && m_limitSoftness < 1.f - SIMD_EPSILON) |
---|
677 | { |
---|
678 | m_swingLimitRatio = (swingAngle - swingLimit * m_limitSoftness)/ |
---|
679 | (swingLimit - swingLimit * m_limitSoftness); |
---|
680 | } |
---|
681 | |
---|
682 | // swing correction tries to get back to soft limit |
---|
683 | m_swingCorrection = swingAngle - (swingLimit * m_limitSoftness); |
---|
684 | |
---|
685 | // adjustment of swing axis (based on ellipse normal) |
---|
686 | adjustSwingAxisToUseEllipseNormal(swingAxis); |
---|
687 | |
---|
688 | // Calculate necessary axis & factors |
---|
689 | m_swingAxis = quatRotate(qB, -swingAxis); |
---|
690 | |
---|
691 | m_twistAxisA.setValue(0,0,0); |
---|
692 | |
---|
693 | m_kSwing = btScalar(1.) / |
---|
694 | (computeAngularImpulseDenominator(m_swingAxis,invInertiaWorldA) + |
---|
695 | computeAngularImpulseDenominator(m_swingAxis,invInertiaWorldB)); |
---|
696 | } |
---|
697 | } |
---|
698 | else |
---|
699 | { |
---|
700 | // you haven't set any limits; |
---|
701 | // or you're trying to set at least one of the swing limits too small. (if so, do you really want a conetwist constraint?) |
---|
702 | // anyway, we have either hinge or fixed joint |
---|
703 | btVector3 ivA = transA.getBasis() * m_rbAFrame.getBasis().getColumn(0); |
---|
704 | btVector3 jvA = transA.getBasis() * m_rbAFrame.getBasis().getColumn(1); |
---|
705 | btVector3 kvA = transA.getBasis() * m_rbAFrame.getBasis().getColumn(2); |
---|
706 | btVector3 ivB = transB.getBasis() * m_rbBFrame.getBasis().getColumn(0); |
---|
707 | btVector3 target; |
---|
708 | btScalar x = ivB.dot(ivA); |
---|
709 | btScalar y = ivB.dot(jvA); |
---|
710 | btScalar z = ivB.dot(kvA); |
---|
711 | if((m_swingSpan1 < m_fixThresh) && (m_swingSpan2 < m_fixThresh)) |
---|
712 | { // fixed. We'll need to add one more row to constraint |
---|
713 | if((!btFuzzyZero(y)) || (!(btFuzzyZero(z)))) |
---|
714 | { |
---|
715 | m_solveSwingLimit = true; |
---|
716 | m_swingAxis = -ivB.cross(ivA); |
---|
717 | } |
---|
718 | } |
---|
719 | else |
---|
720 | { |
---|
721 | if(m_swingSpan1 < m_fixThresh) |
---|
722 | { // hinge around Y axis |
---|
723 | if(!(btFuzzyZero(y))) |
---|
724 | { |
---|
725 | m_solveSwingLimit = true; |
---|
726 | if(m_swingSpan2 >= m_fixThresh) |
---|
727 | { |
---|
728 | y = btScalar(0.f); |
---|
729 | btScalar span2 = btAtan2(z, x); |
---|
730 | if(span2 > m_swingSpan2) |
---|
731 | { |
---|
732 | x = btCos(m_swingSpan2); |
---|
733 | z = btSin(m_swingSpan2); |
---|
734 | } |
---|
735 | else if(span2 < -m_swingSpan2) |
---|
736 | { |
---|
737 | x = btCos(m_swingSpan2); |
---|
738 | z = -btSin(m_swingSpan2); |
---|
739 | } |
---|
740 | } |
---|
741 | } |
---|
742 | } |
---|
743 | else |
---|
744 | { // hinge around Z axis |
---|
745 | if(!btFuzzyZero(z)) |
---|
746 | { |
---|
747 | m_solveSwingLimit = true; |
---|
748 | if(m_swingSpan1 >= m_fixThresh) |
---|
749 | { |
---|
750 | z = btScalar(0.f); |
---|
751 | btScalar span1 = btAtan2(y, x); |
---|
752 | if(span1 > m_swingSpan1) |
---|
753 | { |
---|
754 | x = btCos(m_swingSpan1); |
---|
755 | y = btSin(m_swingSpan1); |
---|
756 | } |
---|
757 | else if(span1 < -m_swingSpan1) |
---|
758 | { |
---|
759 | x = btCos(m_swingSpan1); |
---|
760 | y = -btSin(m_swingSpan1); |
---|
761 | } |
---|
762 | } |
---|
763 | } |
---|
764 | } |
---|
765 | target[0] = x * ivA[0] + y * jvA[0] + z * kvA[0]; |
---|
766 | target[1] = x * ivA[1] + y * jvA[1] + z * kvA[1]; |
---|
767 | target[2] = x * ivA[2] + y * jvA[2] + z * kvA[2]; |
---|
768 | target.normalize(); |
---|
769 | m_swingAxis = -ivB.cross(target); |
---|
770 | m_swingCorrection = m_swingAxis.length(); |
---|
771 | m_swingAxis.normalize(); |
---|
772 | } |
---|
773 | } |
---|
774 | |
---|
775 | if (m_twistSpan >= btScalar(0.f)) |
---|
776 | { |
---|
777 | btVector3 twistAxis; |
---|
778 | computeTwistLimitInfo(qABTwist, m_twistAngle, twistAxis); |
---|
779 | |
---|
780 | if (m_twistAngle > m_twistSpan*m_limitSoftness) |
---|
781 | { |
---|
782 | m_solveTwistLimit = true; |
---|
783 | |
---|
784 | m_twistLimitRatio = 1.f; |
---|
785 | if (m_twistAngle < m_twistSpan && m_limitSoftness < 1.f - SIMD_EPSILON) |
---|
786 | { |
---|
787 | m_twistLimitRatio = (m_twistAngle - m_twistSpan * m_limitSoftness)/ |
---|
788 | (m_twistSpan - m_twistSpan * m_limitSoftness); |
---|
789 | } |
---|
790 | |
---|
791 | // twist correction tries to get back to soft limit |
---|
792 | m_twistCorrection = m_twistAngle - (m_twistSpan * m_limitSoftness); |
---|
793 | |
---|
794 | m_twistAxis = quatRotate(qB, -twistAxis); |
---|
795 | |
---|
796 | m_kTwist = btScalar(1.) / |
---|
797 | (computeAngularImpulseDenominator(m_twistAxis,invInertiaWorldA) + |
---|
798 | computeAngularImpulseDenominator(m_twistAxis,invInertiaWorldB)); |
---|
799 | } |
---|
800 | |
---|
801 | if (m_solveSwingLimit) |
---|
802 | m_twistAxisA = quatRotate(qA, -twistAxis); |
---|
803 | } |
---|
804 | else |
---|
805 | { |
---|
806 | m_twistAngle = btScalar(0.f); |
---|
807 | } |
---|
808 | } |
---|
809 | } |
---|
810 | |
---|
811 | |
---|
812 | |
---|
813 | // given a cone rotation in constraint space, (pre: twist must already be removed) |
---|
814 | // this method computes its corresponding swing angle and axis. |
---|
815 | // more interestingly, it computes the cone/swing limit (angle) for this cone "pose". |
---|
816 | void btConeTwistConstraint::computeConeLimitInfo(const btQuaternion& qCone, |
---|
817 | btScalar& swingAngle, // out |
---|
818 | btVector3& vSwingAxis, // out |
---|
819 | btScalar& swingLimit) // out |
---|
820 | { |
---|
821 | swingAngle = qCone.getAngle(); |
---|
822 | if (swingAngle > SIMD_EPSILON) |
---|
823 | { |
---|
824 | vSwingAxis = btVector3(qCone.x(), qCone.y(), qCone.z()); |
---|
825 | vSwingAxis.normalize(); |
---|
826 | if (fabs(vSwingAxis.x()) > SIMD_EPSILON) |
---|
827 | { |
---|
828 | // non-zero twist?! this should never happen. |
---|
829 | int wtf = 0; wtf = wtf; |
---|
830 | } |
---|
831 | |
---|
832 | // Compute limit for given swing. tricky: |
---|
833 | // Given a swing axis, we're looking for the intersection with the bounding cone ellipse. |
---|
834 | // (Since we're dealing with angles, this ellipse is embedded on the surface of a sphere.) |
---|
835 | |
---|
836 | // For starters, compute the direction from center to surface of ellipse. |
---|
837 | // This is just the perpendicular (ie. rotate 2D vector by PI/2) of the swing axis. |
---|
838 | // (vSwingAxis is the cone rotation (in z,y); change vars and rotate to (x,y) coords.) |
---|
839 | btScalar xEllipse = vSwingAxis.y(); |
---|
840 | btScalar yEllipse = -vSwingAxis.z(); |
---|
841 | |
---|
842 | // Now, we use the slope of the vector (using x/yEllipse) and find the length |
---|
843 | // of the line that intersects the ellipse: |
---|
844 | // x^2 y^2 |
---|
845 | // --- + --- = 1, where a and b are semi-major axes 2 and 1 respectively (ie. the limits) |
---|
846 | // a^2 b^2 |
---|
847 | // Do the math and it should be clear. |
---|
848 | |
---|
849 | swingLimit = m_swingSpan1; // if xEllipse == 0, we have a pure vSwingAxis.z rotation: just use swingspan1 |
---|
850 | if (fabs(xEllipse) > SIMD_EPSILON) |
---|
851 | { |
---|
852 | btScalar surfaceSlope2 = (yEllipse*yEllipse)/(xEllipse*xEllipse); |
---|
853 | btScalar norm = 1 / (m_swingSpan2 * m_swingSpan2); |
---|
854 | norm += surfaceSlope2 / (m_swingSpan1 * m_swingSpan1); |
---|
855 | btScalar swingLimit2 = (1 + surfaceSlope2) / norm; |
---|
856 | swingLimit = sqrt(swingLimit2); |
---|
857 | } |
---|
858 | |
---|
859 | // test! |
---|
860 | /*swingLimit = m_swingSpan2; |
---|
861 | if (fabs(vSwingAxis.z()) > SIMD_EPSILON) |
---|
862 | { |
---|
863 | btScalar mag_2 = m_swingSpan1*m_swingSpan1 + m_swingSpan2*m_swingSpan2; |
---|
864 | btScalar sinphi = m_swingSpan2 / sqrt(mag_2); |
---|
865 | btScalar phi = asin(sinphi); |
---|
866 | btScalar theta = atan2(fabs(vSwingAxis.y()),fabs(vSwingAxis.z())); |
---|
867 | btScalar alpha = 3.14159f - theta - phi; |
---|
868 | btScalar sinalpha = sin(alpha); |
---|
869 | swingLimit = m_swingSpan1 * sinphi/sinalpha; |
---|
870 | }*/ |
---|
871 | } |
---|
872 | else if (swingAngle < 0) |
---|
873 | { |
---|
874 | // this should never happen! |
---|
875 | int wtf = 0; wtf = wtf; |
---|
876 | } |
---|
877 | } |
---|
878 | |
---|
879 | btVector3 btConeTwistConstraint::GetPointForAngle(btScalar fAngleInRadians, btScalar fLength) const |
---|
880 | { |
---|
881 | // compute x/y in ellipse using cone angle (0 -> 2*PI along surface of cone) |
---|
882 | btScalar xEllipse = btCos(fAngleInRadians); |
---|
883 | btScalar yEllipse = btSin(fAngleInRadians); |
---|
884 | |
---|
885 | // Use the slope of the vector (using x/yEllipse) and find the length |
---|
886 | // of the line that intersects the ellipse: |
---|
887 | // x^2 y^2 |
---|
888 | // --- + --- = 1, where a and b are semi-major axes 2 and 1 respectively (ie. the limits) |
---|
889 | // a^2 b^2 |
---|
890 | // Do the math and it should be clear. |
---|
891 | |
---|
892 | float swingLimit = m_swingSpan1; // if xEllipse == 0, just use axis b (1) |
---|
893 | if (fabs(xEllipse) > SIMD_EPSILON) |
---|
894 | { |
---|
895 | btScalar surfaceSlope2 = (yEllipse*yEllipse)/(xEllipse*xEllipse); |
---|
896 | btScalar norm = 1 / (m_swingSpan2 * m_swingSpan2); |
---|
897 | norm += surfaceSlope2 / (m_swingSpan1 * m_swingSpan1); |
---|
898 | btScalar swingLimit2 = (1 + surfaceSlope2) / norm; |
---|
899 | swingLimit = sqrt(swingLimit2); |
---|
900 | } |
---|
901 | |
---|
902 | // convert into point in constraint space: |
---|
903 | // note: twist is x-axis, swing 1 and 2 are along the z and y axes respectively |
---|
904 | btVector3 vSwingAxis(0, xEllipse, -yEllipse); |
---|
905 | btQuaternion qSwing(vSwingAxis, swingLimit); |
---|
906 | btVector3 vPointInConstraintSpace(fLength,0,0); |
---|
907 | return quatRotate(qSwing, vPointInConstraintSpace); |
---|
908 | } |
---|
909 | |
---|
910 | // given a twist rotation in constraint space, (pre: cone must already be removed) |
---|
911 | // this method computes its corresponding angle and axis. |
---|
912 | void btConeTwistConstraint::computeTwistLimitInfo(const btQuaternion& qTwist, |
---|
913 | btScalar& twistAngle, // out |
---|
914 | btVector3& vTwistAxis) // out |
---|
915 | { |
---|
916 | btQuaternion qMinTwist = qTwist; |
---|
917 | twistAngle = qTwist.getAngle(); |
---|
918 | |
---|
919 | if (twistAngle > SIMD_PI) // long way around. flip quat and recalculate. |
---|
920 | { |
---|
921 | qMinTwist = operator-(qTwist); |
---|
922 | twistAngle = qMinTwist.getAngle(); |
---|
923 | } |
---|
924 | if (twistAngle < 0) |
---|
925 | { |
---|
926 | // this should never happen |
---|
927 | int wtf = 0; wtf = wtf; |
---|
928 | } |
---|
929 | |
---|
930 | vTwistAxis = btVector3(qMinTwist.x(), qMinTwist.y(), qMinTwist.z()); |
---|
931 | if (twistAngle > SIMD_EPSILON) |
---|
932 | vTwistAxis.normalize(); |
---|
933 | } |
---|
934 | |
---|
935 | |
---|
936 | void btConeTwistConstraint::adjustSwingAxisToUseEllipseNormal(btVector3& vSwingAxis) const |
---|
937 | { |
---|
938 | // the swing axis is computed as the "twist-free" cone rotation, |
---|
939 | // but the cone limit is not circular, but elliptical (if swingspan1 != swingspan2). |
---|
940 | // so, if we're outside the limits, the closest way back inside the cone isn't |
---|
941 | // along the vector back to the center. better (and more stable) to use the ellipse normal. |
---|
942 | |
---|
943 | // convert swing axis to direction from center to surface of ellipse |
---|
944 | // (ie. rotate 2D vector by PI/2) |
---|
945 | btScalar y = -vSwingAxis.z(); |
---|
946 | btScalar z = vSwingAxis.y(); |
---|
947 | |
---|
948 | // do the math... |
---|
949 | if (fabs(z) > SIMD_EPSILON) // avoid division by 0. and we don't need an update if z == 0. |
---|
950 | { |
---|
951 | // compute gradient/normal of ellipse surface at current "point" |
---|
952 | btScalar grad = y/z; |
---|
953 | grad *= m_swingSpan2 / m_swingSpan1; |
---|
954 | |
---|
955 | // adjust y/z to represent normal at point (instead of vector to point) |
---|
956 | if (y > 0) |
---|
957 | y = fabs(grad * z); |
---|
958 | else |
---|
959 | y = -fabs(grad * z); |
---|
960 | |
---|
961 | // convert ellipse direction back to swing axis |
---|
962 | vSwingAxis.setZ(-y); |
---|
963 | vSwingAxis.setY( z); |
---|
964 | vSwingAxis.normalize(); |
---|
965 | } |
---|
966 | } |
---|
967 | |
---|
968 | |
---|
969 | |
---|
970 | void btConeTwistConstraint::setMotorTarget(const btQuaternion &q) |
---|
971 | { |
---|
972 | btTransform trACur = m_rbA.getCenterOfMassTransform(); |
---|
973 | btTransform trBCur = m_rbB.getCenterOfMassTransform(); |
---|
974 | btTransform trABCur = trBCur.inverse() * trACur; |
---|
975 | btQuaternion qABCur = trABCur.getRotation(); |
---|
976 | btTransform trConstraintCur = (trBCur * m_rbBFrame).inverse() * (trACur * m_rbAFrame); |
---|
977 | btQuaternion qConstraintCur = trConstraintCur.getRotation(); |
---|
978 | |
---|
979 | btQuaternion qConstraint = m_rbBFrame.getRotation().inverse() * q * m_rbAFrame.getRotation(); |
---|
980 | setMotorTargetInConstraintSpace(qConstraint); |
---|
981 | } |
---|
982 | |
---|
983 | |
---|
984 | void btConeTwistConstraint::setMotorTargetInConstraintSpace(const btQuaternion &q) |
---|
985 | { |
---|
986 | m_qTarget = q; |
---|
987 | |
---|
988 | // clamp motor target to within limits |
---|
989 | { |
---|
990 | btScalar softness = 1.f;//m_limitSoftness; |
---|
991 | |
---|
992 | // split into twist and cone |
---|
993 | btVector3 vTwisted = quatRotate(m_qTarget, vTwist); |
---|
994 | btQuaternion qTargetCone = shortestArcQuat(vTwist, vTwisted); qTargetCone.normalize(); |
---|
995 | btQuaternion qTargetTwist = qTargetCone.inverse() * m_qTarget; qTargetTwist.normalize(); |
---|
996 | |
---|
997 | // clamp cone |
---|
998 | if (m_swingSpan1 >= btScalar(0.05f) && m_swingSpan2 >= btScalar(0.05f)) |
---|
999 | { |
---|
1000 | btScalar swingAngle, swingLimit; btVector3 swingAxis; |
---|
1001 | computeConeLimitInfo(qTargetCone, swingAngle, swingAxis, swingLimit); |
---|
1002 | |
---|
1003 | if (fabs(swingAngle) > SIMD_EPSILON) |
---|
1004 | { |
---|
1005 | if (swingAngle > swingLimit*softness) |
---|
1006 | swingAngle = swingLimit*softness; |
---|
1007 | else if (swingAngle < -swingLimit*softness) |
---|
1008 | swingAngle = -swingLimit*softness; |
---|
1009 | qTargetCone = btQuaternion(swingAxis, swingAngle); |
---|
1010 | } |
---|
1011 | } |
---|
1012 | |
---|
1013 | // clamp twist |
---|
1014 | if (m_twistSpan >= btScalar(0.05f)) |
---|
1015 | { |
---|
1016 | btScalar twistAngle; btVector3 twistAxis; |
---|
1017 | computeTwistLimitInfo(qTargetTwist, twistAngle, twistAxis); |
---|
1018 | |
---|
1019 | if (fabs(twistAngle) > SIMD_EPSILON) |
---|
1020 | { |
---|
1021 | // eddy todo: limitSoftness used here??? |
---|
1022 | if (twistAngle > m_twistSpan*softness) |
---|
1023 | twistAngle = m_twistSpan*softness; |
---|
1024 | else if (twistAngle < -m_twistSpan*softness) |
---|
1025 | twistAngle = -m_twistSpan*softness; |
---|
1026 | qTargetTwist = btQuaternion(twistAxis, twistAngle); |
---|
1027 | } |
---|
1028 | } |
---|
1029 | |
---|
1030 | m_qTarget = qTargetCone * qTargetTwist; |
---|
1031 | } |
---|
1032 | } |
---|
1033 | |
---|
1034 | ///override the default global value of a parameter (such as ERP or CFM), optionally provide the axis (0..5). |
---|
1035 | ///If no axis is provided, it uses the default axis for this constraint. |
---|
1036 | void btConeTwistConstraint::setParam(int num, btScalar value, int axis) |
---|
1037 | { |
---|
1038 | switch(num) |
---|
1039 | { |
---|
1040 | case BT_CONSTRAINT_ERP : |
---|
1041 | case BT_CONSTRAINT_STOP_ERP : |
---|
1042 | if((axis >= 0) && (axis < 3)) |
---|
1043 | { |
---|
1044 | m_linERP = value; |
---|
1045 | m_flags |= BT_CONETWIST_FLAGS_LIN_ERP; |
---|
1046 | } |
---|
1047 | else |
---|
1048 | { |
---|
1049 | m_biasFactor = value; |
---|
1050 | } |
---|
1051 | break; |
---|
1052 | case BT_CONSTRAINT_CFM : |
---|
1053 | case BT_CONSTRAINT_STOP_CFM : |
---|
1054 | if((axis >= 0) && (axis < 3)) |
---|
1055 | { |
---|
1056 | m_linCFM = value; |
---|
1057 | m_flags |= BT_CONETWIST_FLAGS_LIN_CFM; |
---|
1058 | } |
---|
1059 | else |
---|
1060 | { |
---|
1061 | m_angCFM = value; |
---|
1062 | m_flags |= BT_CONETWIST_FLAGS_ANG_CFM; |
---|
1063 | } |
---|
1064 | break; |
---|
1065 | default: |
---|
1066 | btAssertConstrParams(0); |
---|
1067 | break; |
---|
1068 | } |
---|
1069 | } |
---|
1070 | |
---|
1071 | ///return the local value of parameter |
---|
1072 | btScalar btConeTwistConstraint::getParam(int num, int axis) const |
---|
1073 | { |
---|
1074 | btScalar retVal = 0; |
---|
1075 | switch(num) |
---|
1076 | { |
---|
1077 | case BT_CONSTRAINT_ERP : |
---|
1078 | case BT_CONSTRAINT_STOP_ERP : |
---|
1079 | if((axis >= 0) && (axis < 3)) |
---|
1080 | { |
---|
1081 | btAssertConstrParams(m_flags & BT_CONETWIST_FLAGS_LIN_ERP); |
---|
1082 | retVal = m_linERP; |
---|
1083 | } |
---|
1084 | else if((axis >= 3) && (axis < 6)) |
---|
1085 | { |
---|
1086 | retVal = m_biasFactor; |
---|
1087 | } |
---|
1088 | else |
---|
1089 | { |
---|
1090 | btAssertConstrParams(0); |
---|
1091 | } |
---|
1092 | break; |
---|
1093 | case BT_CONSTRAINT_CFM : |
---|
1094 | case BT_CONSTRAINT_STOP_CFM : |
---|
1095 | if((axis >= 0) && (axis < 3)) |
---|
1096 | { |
---|
1097 | btAssertConstrParams(m_flags & BT_CONETWIST_FLAGS_LIN_CFM); |
---|
1098 | retVal = m_linCFM; |
---|
1099 | } |
---|
1100 | else if((axis >= 3) && (axis < 6)) |
---|
1101 | { |
---|
1102 | btAssertConstrParams(m_flags & BT_CONETWIST_FLAGS_ANG_CFM); |
---|
1103 | retVal = m_angCFM; |
---|
1104 | } |
---|
1105 | else |
---|
1106 | { |
---|
1107 | btAssertConstrParams(0); |
---|
1108 | } |
---|
1109 | break; |
---|
1110 | default : |
---|
1111 | btAssertConstrParams(0); |
---|
1112 | } |
---|
1113 | return retVal; |
---|
1114 | } |
---|
1115 | |
---|
1116 | |
---|
1117 | void btConeTwistConstraint::setFrames(const btTransform & frameA, const btTransform & frameB) |
---|
1118 | { |
---|
1119 | m_rbAFrame = frameA; |
---|
1120 | m_rbBFrame = frameB; |
---|
1121 | buildJacobian(); |
---|
1122 | //calculateTransforms(); |
---|
1123 | } |
---|
1124 | |
---|
1125 | |
---|
1126 | |
---|
1127 | |
---|