source: orxonox.OLD/branches/cleanup/src/world_entities/effects/trail.cc

/*
   orxonox - the future of 3D-vertical-scrollers

   Copyright (C) 2006 orx

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

### File Specific:

   Trail system for engine output trails.
   uses a catmull rom spline to interpolate the curve which is subdivided
   into sections parts.
   main-programmer: Marc Schaerer
*/

#include "trail.h"

#include "util/loading/load_param.h"
#include "util/loading/factory.h"

#include "graphics_engine.h"
#include "material.h"
#include "glincl.h"
#include "state.h"
#include "debug.h"



#define trailAlphaMax 1.0f
#define trailAlphaMin 0.2f

ObjectListDefinition(Trail);
CREATE_FACTORY(Trail);

/**
 * standart constructor
 * @param maxLength maximum length of the trail. You will later need to set the actual length used.
 * @param sections number of sections into which the trail polygon shall be splited. Higher number for more smooth curves
 * @param radius radius of the trail cross.
 * 
 */
Trail::Trail (float maxLength, int sections, float radius, PNode* parent)
{
  this->maxLength = maxLength;
  this->length    = 1.0;
  this->sections  = sections;
  this->radius    = radius;
  this->setParent( parent);

  this->nodeList  = new Vector[sections];


  this->init();
}

Trail::Trail (const TiXmlElement* root)
{
  this->init();

  if( root)
    this->loadParams(root);
}

/**
 * destroys a Trail
 */
Trail::~Trail ()
{
  if (this->material)
    delete this->material;
  delete this->nodeList;
}


/**
 * initializes the Trail
 */
void Trail::init()
{
  this->registerObject(this, Trail::_objectList);
  this->setName("Trail");

  this->material = new Material();
  this->material->setIllum(3);
  this->material->setDiffuse(1.0,1.0,1.0);
  this->material->setSpecular(0.0,0.0,0.0);
  this->material->setAmbient(1.0, 1.0, 1.0);

  this->setAbsCoor(0, 0, 0);
  this->setVisibility(true);

  this->nodeList[0] = (this->getAbsCoor());
  //PRINTF(0)("Trail data: N%i (%f,%f,%f)",0,this->getAbsCoor().x,this->getAbsCoor().y,this->getAbsCoor().z);
  for( int i = 1; i < sections; i++)
  {
    this->nodeList[i] = (this->getAbsCoor());// - (((this->getParent()->getAbsDir().apply(Vector(1,1,1))).getNormalized() * (i * this->maxLength / sections))));
    //PRINTF(0)(" N%i (%f,%f,%f)",i,this->nodeList[i].x,this->nodeList[i].y,this->nodeList[i].z);
  }
  //PRINTF(0)("\n");
}


/**
 *  load params
 * @param root TiXmlElement object
 */
void Trail::loadParams(const TiXmlElement* root)
{
  WorldEntity::loadParams( root);
}

/**
 * sets the material to load
 * @param textureFile The texture-file to load
 */
void Trail::setTexture(const std::string& textureFile)
{
  this->material->setDiffuseMap(textureFile);
}


/**
 * ticks the Trail
 * @param dt the time to ticks
 */
void Trail::tick(float dt)
{
  // Update node positions
  float len = 0;
  float secLen  = this->maxLength / this->sections;
  this->nodeList[0] = this->getAbsCoor();
  this->nodeList[1] = this->getAbsCoor() - ((this->getParent()->getAbsDir().apply(Vector(1,0,0))).getNormalized() *  this->maxLength / sections);
  for(int i = 2; i < this->sections; i++)
  {
    len = (this->nodeList[i-1] - this->nodeList[i]).len();
    if( secLen < len) len = secLen;
    this->nodeList[i] = this->nodeList[i-1] - (this->nodeList[i-1] - this->nodeList[i]).getNormalized()*len;
  }
}


/**
 * draws the trail
 * the trail has a cone shape
 */
void Trail::draw() const
{
  if(!this->isVisible())
    return;

  Vector* Q = new Vector[4];
  Vector targ;
  Vector now, later;
  float fact  = 1.0/this->sections;
  float radzero, radone;

  glPushAttrib(GL_ENABLE_BIT);
  
  glPushMatrix();
  //glMatrixMode(GL_MODELVIEW);
  //glLoadIdentity();
  /*
  glEnable(GL_BLEND);
  glBlendFunc(GL_SRC_ALPHA,GL_ONE);
  glDisable( GL_ALPHA_TEST);*/

  glTranslatef(-this->getAbsCoor().x,-this->getAbsCoor().y,-this->getAbsCoor().z);
  glScalef(1,1,1);
  this->material->select();

  //float alphaStep = 1.0 / this->sections;

  glBegin(GL_TRIANGLE_STRIP);

  // Alpha goes from 1.0 to 0.4 -> alphastep = .6 / this->sections
  for( int i = 1; i < this->sections-1; i++)
  {
    radone  = this->radius * (1.0-i*fact + 0.2 * (float)rand()/(float)RAND_MAX);
    radzero  = this->radius * (1.0-(i+1)*fact + 0.2 * (float)rand()/(float)RAND_MAX);

    now   =  this->nodeList[i];
    later =  this->nodeList[i+1];
    if( i == 0)
      targ  = this->getAbsDir().apply(Vector(1,0,0)).getNormalized();
    else
      targ  = (this->getAbsCoor() - now).getNormalized();

    // horizontal polygon
    Q[0]  = now + Vector(0,radone,0) ;
    Q[3]  = now + Vector(0,-radone,0) ;
    
    glTexCoord2f(0.0f, 0.0f); glVertex3f(Q[0].x,Q[0].y,Q[0].z);
        glTexCoord2f(1.0f, 0.0f); glVertex3f(Q[3].x,Q[3].y,Q[3].z);

    if( i == this->sections - 1)
    {
      
      Q[1]  = later + Vector(0,radzero,0) ;
      Q[2]  = later + Vector(0,-radzero,0) ;
      glTexCoord2f(0.0f, 1.0f); glVertex3f(Q[1].x,Q[1].y,Q[1].z);
      glTexCoord2f(1.0f, 1.0f); glVertex3f(Q[2].x,Q[2].y,Q[2].z);
    }


  }
  glEnd();
  glBegin(GL_TRIANGLE_STRIP);
  for( int i = this->sections-1; i > 0; i--)
  {
    radone  = this->radius * (1.0-i*fact + 0.2 * (float)rand()/(float)RAND_MAX);
    radzero  = this->radius * (1.0-(i-1)*fact + 0.2 * (float)rand()/(float)RAND_MAX);

    now   =  this->nodeList[i];
    later =  this->nodeList[i-1];
    if( i == 0)
      targ  = this->getAbsDir().apply(Vector(1,0,0)).getNormalized();
    else
      targ  = (this->getAbsCoor() - now).getNormalized();

    // horizontal polygon
    Q[0]  = now + Vector(0,radone,0) ;
    Q[3]  = now + Vector(0,-radone,0) ;

        glTexCoord2f(1.0f, 0.0f); glVertex3f(Q[3].x,Q[3].y,Q[3].z+0.01f);
        glTexCoord2f(0.0f, 0.0f); glVertex3f(Q[0].x,Q[0].y,Q[0].z+0.01f);

    if( i == 1)
    {
        Q[1]  = later + Vector(0,radzero,0) ;
        Q[2]  = later + Vector(0,-radzero,0) ;

                glTexCoord2f(1.0f, 1.0f); glVertex3f(Q[2].x,Q[2].y,Q[2].z+0.01f);
                glTexCoord2f(0.0f, 1.0f); glVertex3f(Q[1].x,Q[1].y,Q[1].z+0.01f);
        }

  }
  glEnd();


  glBegin(GL_TRIANGLE_STRIP);
  for( int i = 1; i < this->sections-1; i++)
  {
    radone  = this->radius * (1.0-i*fact + 0.2 * (float)rand()/(float)RAND_MAX);
    radzero  = this->radius * (1.0-(i+1)*fact + 0.2 * (float)rand()/(float)RAND_MAX);

    now   =  this->nodeList[i];
    later =  this->nodeList[i+1];
    if( i == 0)
      targ  = this->getAbsDir().apply(Vector(1,0,0)).getNormalized();
    else
      targ  = (this->getAbsCoor() - now).getNormalized();

    // horizontal polygon
    Q[0]  = now + targ.cross(Vector(0,radone,0)) ;
    Q[3]  = now + targ.cross(Vector(0,-radone,0)) ;
    
        glTexCoord2f(0.0f, 0.0f); glVertex3f(Q[0].x,Q[0].y,Q[0].z);
        glTexCoord2f(1.0f, 0.0f); glVertex3f(Q[3].x,Q[3].y,Q[3].z);

    if( i == this->sections-1)
    {
      Q[1]  = later + targ.cross(Vector(0,radzero,0)) ;
      Q[2]  = later + targ.cross(Vector(0,-radzero,0)) ;
      glTexCoord2f(0.0f, 1.0f); glVertex3f(Q[1].x,Q[1].y,Q[1].z);
      glTexCoord2f(1.0f, 1.0f); glVertex3f(Q[2].x,Q[2].y,Q[2].z);
    }


  }
  glEnd();
  glBegin(GL_TRIANGLE_STRIP);
  for( int i = this->sections-1; i > 0; i--)
  {
    radone  = this->radius * (1.0-i*fact + 0.2 * (float)rand()/(float)RAND_MAX);
    radzero  = this->radius * (1.0-(i-1)*fact + 0.2 * (float)rand()/(float)RAND_MAX);

    now   =  this->nodeList[i];
    later =  this->nodeList[i-1];
    if( i == 0)
      targ  = this->getAbsDir().apply(Vector(1,0,0)).getNormalized();
    else
      targ  = (this->getAbsCoor() - now).getNormalized();

    // horizontal polygon
    Q[0]  = now + targ.cross(Vector(0,radone,0)) ;
    Q[3]  = now + targ.cross(Vector(0,-radone,0)) ;

        glTexCoord2f(0.0f, 0.0f); glVertex3f(Q[0].x+0.01f,Q[0].y,Q[0].z);
        glTexCoord2f(1.0f, 0.0f); glVertex3f(Q[3].x+0.01f,Q[3].y,Q[3].z);

    if( i == 1)
    {
        Q[1]  = later + targ.cross(Vector(0,radzero,0)) ;
        Q[2]  = later + targ.cross(Vector(0,-radzero,0)) ;

                glTexCoord2f(0.0f, 1.0f); glVertex3f(Q[1].x+0.01f,Q[1].y,Q[1].z);
                glTexCoord2f(1.0f, 1.0f); glVertex3f(Q[2].x+0.01f,Q[2].y,Q[2].z);
        }

  }
  glEnd();
  this->material->unselect();

  glPopMatrix();
  glPopAttrib();
}