source: data/data_extern/programs/Cg/ParticleGS.cg @ 12397

//
// Explanation of different particle types
//
#define PT_LAUNCHER 0 //Firework Launcher - launches a PT_SHELL every so many seconds
#define PT_SHELL    1 //Unexploded shell - flies from the origin and explodes into many PT_EMBERXs
#define PT_EMBER1   2 //basic particle - after it's emitted from the shell, it dies
#define PT_EMBER2   3 //after it's emitted, it explodes again into many PT_EMBER1s
#define PT_EMBER3   4 //just a differently colored ember1
#define P_SHELLLIFE 3.0
#define P_EMBER1LIFE 2.5
#define P_EMBER2LIFE 1.5
#define P_EMBER3LIFE 2.0

//These two were originally shader params, but they caused runtime errors
#define NUM_EMBER_1S 30
#define NUM_EMBER_2S 15
#define NUM_EMBER_3S 10
//This one was originally a variant, but this also causes runtime errors
//#define MAX_EMBER_2S 15.0

//
// Generic particle motion handler
//

void GSGenericHandler( float3 Pos, float3 Vel, float Timer, float Type,
                                                float elapsedTime, 
                                                float3 frameGravity)
{
    Pos += Vel * elapsedTime;
    Vel += frameGravity;
    Timer -= elapsedTime;
        if (Pos.y > -100)
        {
                emitVertex( Pos : POSITION, Vel : TEXCOORD2, Timer : TEXCOORD0, Type : TEXCOORD1);
        }
}

//
// Sample a random direction from our random texture
//
float3 RandomDir(float fOffset, float globalTime, sampler1D randomTex)
{
    float tCoord = (globalTime + fOffset) / 300.0;
    return tex1D(randomTex, tCoord).rgb;
}

//
// Launcher type particle handler
//
void GSLauncherHandler( float3 Pos, float3 Vel, float Timer, float Type, 
                                                float elapsedTime, 
                                                float globalTime, 
                                                sampler1D randomTex,
                                                float secondsPerFirework)
{
    if(Timer <= 0)
    {
        float3 vRandom = normalize( RandomDir( Type, globalTime, randomTex) );
                //Give it more of an up bias
        vRandom = normalize(vRandom + float3(0,2.5,0)); 
                
                //time to emit a new SHELL
        float3 outputPos = Pos + Vel*elapsedTime;
        float3 outputVel = Vel + vRandom*35.0;
        float  outputTimer = P_SHELLLIFE + vRandom.y*0.5;
        float outputType = PT_SHELL;
        emitVertex(outputPos : POSITION, outputVel : TEXCOORD2, outputTimer : TEXCOORD0, outputType : TEXCOORD1);
        
        //reset our timer
        Timer = secondsPerFirework + vRandom.x*0.4;
    }
    else
    {
        Timer -= elapsedTime;
    }
    
    //emit ourselves to keep us alive
    emitVertex( Pos : POSITION, Vel : TEXCOORD2, Timer : TEXCOORD0, Type : TEXCOORD1);
}

//
// Shell type particle handler
//      
void GSShellHandler( float3 Pos, float3 Vel, float Timer, float Type,
                                        float elapsedTime, 
                                        float globalTime, 
                                        sampler1D randomTex,
                                        float3 frameGravity)
{
    if(Timer <= 0)
    {
        float3 outputPos;
                float3 outputVel;
                float outputTimer;
                float outputType;
                
        float3 vRandom = float3(0,0,0);
        
        //time to emit a series of new Ember1s  
        for(int i=0; i<NUM_EMBER_1S; i++)
        {
            vRandom = normalize( RandomDir( Type+i, globalTime, randomTex ) );
            outputPos = Pos + Vel*elapsedTime;
            outputVel = Vel + vRandom*15.0;
            outputTimer = P_EMBER1LIFE;
            outputType = PT_EMBER1;
            emitVertex(outputPos : POSITION, outputTimer : TEXCOORD0, outputType : TEXCOORD1, outputVel : TEXCOORD2);
        }
        
        //find out how many Ember2s to emit
                //Not doing this because it causes a runtime error
                //int numEmber2s = abs(vRandom.x)*MAX_EMBER_2S;
        for(int i=0; i<NUM_EMBER_2S; i++)
        {
            vRandom = normalize( RandomDir( Type, globalTime, randomTex) );
            outputPos = Pos + Vel*elapsedTime;
            outputVel = Vel + vRandom*10.0;
            outputTimer = P_EMBER2LIFE + 0.4*vRandom.x;
            outputType = PT_EMBER2;
            emitVertex(outputPos : POSITION, outputVel : TEXCOORD2, outputTimer : TEXCOORD0, outputType : TEXCOORD1);
        }
        
    }
    else
    {
        GSGenericHandler(Pos, Vel, Timer, Type, elapsedTime, frameGravity );
    }
}

//
// Ember1 and Ember3 type particle handler
//
void GSEmber1Handler( float3 Pos, float3 Vel, float Timer, float Type,
                                                float elapsedTime, 
                                                float3 frameGravity)
{
    if(Timer > 0)
    {
        GSGenericHandler(Pos, Vel, Timer, Type, elapsedTime, frameGravity );
    }
}

//
// Ember2 type particle handler
//
void GSEmber2Handler( float3 Pos, float3 Vel, float Timer, float Type,
                                                float elapsedTime, 
                                                float globalTime, 
                                                sampler1D randomTex,
                                                float3 frameGravity)
{
    if(Timer <= 0)
    {
                float3 outputPos;
                float3 outputVel;
                float outputTimer;
                float outputType;
    
        //time to emit a series of new Ember3s  
        for(int i=0; i<NUM_EMBER_3S; i++)
        {
            outputPos = Pos + Vel*elapsedTime;
            outputVel = Vel + normalize( RandomDir( Type + i, globalTime, randomTex ) )*10.0;
            outputTimer = P_EMBER3LIFE;
            outputType = PT_EMBER3;
            emitVertex(outputPos : POSITION, outputVel : TEXCOORD2, outputTimer : TEXCOORD0, outputType : TEXCOORD1);
        }
    }
    else
    {
         GSGenericHandler(Pos, Vel, Timer, Type, elapsedTime, frameGravity );
    }
}

struct FireworkData
{
        float4  Pos     : POSITION;
        float   Timer   : TEXCOORD0;
    float       Type    : TEXCOORD1;
        float3  Velocity : TEXCOORD2;
};

//The vertex shader that prepares the fireworks for display
FireworkData GenerateParticles_VS(
    in float4           inPos : POSITION,       
        in float                inTimer : TEXCOORD0,
        in float                inType : TEXCOORD1,
        in float3               inVelocity : TEXCOORD2
        )
{
        FireworkData output;
        output.Pos = inPos;
        output.Timer = inTimer;
        output.Type = inType;
        output.Velocity = inVelocity;
        
        return output;
}

POINT
POINT_OUT
void GenerateParticles_GS(
        AttribArray<float3> Pos : POSITION,
        AttribArray<float> Timer : TEXCOORD0,
        AttribArray<float> Type : TEXCOORD1,
        AttribArray<float3> Vel : TEXCOORD2,
        
        uniform sampler1D randomTex : TEXUNIT0,
        uniform float3 frameGravity,
        uniform float globalTime,
        uniform float elapsedTime,
        uniform float secondsPerFirework
        )
{
        if( Type[0] == PT_LAUNCHER )
        GSLauncherHandler( Pos[0], Vel[0], Timer[0], Type[0], 
                                                        elapsedTime, globalTime, randomTex, secondsPerFirework);
        else if ( Type[0] == PT_SHELL )
        GSShellHandler( Pos[0], Vel[0], Timer[0], Type[0], 
                                                        elapsedTime, globalTime, randomTex, frameGravity);
        else if ( Type[0] == PT_EMBER1 ||
              Type[0] == PT_EMBER3 )
       GSEmber1Handler( Pos[0], Vel[0], Timer[0], Type[0], 
                                                        elapsedTime, frameGravity);
    else if( Type[0] == PT_EMBER2 )
        GSEmber2Handler( Pos[0], Vel[0], Timer[0], Type[0], 
                                                        elapsedTime, globalTime, randomTex, frameGravity);
}

struct ColoredFirework
{
        float3  pos : POSITION;
    float4      color : COLOR;
        float   radius : TEXCOORD0;
};

//The vertex shader that prepares the fireworks for display
ColoredFirework DisplayParticles_VS
(
    in float3           inPos : POSITION,
        in float                inTimer : TEXCOORD0,
        in float                inType : TEXCOORD1,
        in float3               inVelocity : TEXCOORD2
        

    //uniform float4x4 worldViewProj
)
{
        ColoredFirework output;
    //
    // Pass the point through
    //
    output.pos = inPos; //Multiply by world matrix?
    output.radius = 1.5;
    
    //  
    // calculate the color
    //
    if( inType == PT_LAUNCHER )
    {
        output.color = float4(1,0.1,0.1,1);
        output.radius = 1.0;
    }
    else if( inType == PT_SHELL )
    {
        output.color = float4(0.1,1,1,1);
        output.radius = 1.0;
    }
    else if( inType == PT_EMBER1 )
    {
        output.color = float4(1,1,0.1,1);
        output.color *= (inTimer / P_EMBER1LIFE );
    }
    else if( inType == PT_EMBER2 )
    {
        output.color = float4(1,0.1,1,1);
    }
    else if( inType == PT_EMBER3 )
    {
        output.color = float4(1,0.1,0.1,1);
        output.color *= (inTimer / P_EMBER3LIFE );
    }
    
    return output;
}

//The geometry shader that prepares the fireworks for display
POINT 
TRIANGLE_OUT 
void DisplayParticles_GS( AttribArray<float3> Pos : POSITION,
                                                        AttribArray<float4> Color : COLOR,
                                                        AttribArray<float> Radius : TEXCOORD0,
                                                        
                                                        uniform float4x4 inverseView,
                                                        uniform float4x4 worldViewProj)
{
        //float3 g_positions[4] = { float3( -1, 1, 0 ), float3( 1, 1, 0 ), float3( -1, -1, 0 ), float3( 1, -1, 0 ) };
        float3 g_positions[4] = { float3( -1, 1, 0 ), float3( -1, -1, 0 ), float3( 1, 1, 0 ), float3( 1, -1, 0 ) };
    float2 g_texcoords[4] = { float2(0,1), float2(1,1), float2(0,0), float2(1,0) };
        
        
        //
    // Emit two new triangles
    //
    for(int i=0; i<4; i++)
    {
                float3 position = -g_positions[i]*Radius[0];
        position = mul( (float3x3)inverseView, position ) + Pos[0];
        float4 outPos = mul( worldViewProj, float4(position,1.0) );
        
        emitVertex(outPos : POSITION, Color[0] : COLOR0, g_texcoords[i] : TEXCOORD0);
    }
    restartStrip();
}

//The pixels shaders that colors the fireworks
float4 DisplayParticles_PS(     float2 iTexCoord : TEXCOORD0,
                                                        float4 iColor : COLOR0,
                                                        uniform sampler diffuseTex : register(s0)) : COLOR
{
        return tex2D(diffuseTex, iTexCoord) * iColor;
        //return float4(iTexCoord.x, iTexCoord.y, 0, 1) + iColor * 0.01;
        //return float4(iTexCoord.xy, 0, 1) * 0.3 + tex2D(diffuseTex, iTexCoord) * 0.7 + iColor * 0.01;
}