PSystem.cpp

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//
// Das Tank - Copyright (C) 2006, 2007 Windsor Schmidt <windsor@windsorworld.net>
//
// 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 of the License, or (at your option)
// any later version.
//
// This program is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
// more details.
//
// You should have received a copy of the GNU General Public License along with
// this program; if not, write to the Free Software Foundation, Inc., 59 Temple
// Place, Suite 330, Boston, MA 02111-1307 USA
//


#ifndef STDAFX
#include "stdafx.h"
#endif

PSystem::PSystem(void)
{
       int i;
       vPosition.x = 0;
       vPosition.y = 0;
       vPosition.z = 0;

       vForce.x = 0;
       vForce.y = 0;
       vForce.z = 0;

       fSpreadAngle = PI/2; // 90 degrees
       fFriction = 1;
       iNumParticles = 1;

       pParticles = (Particle *) malloc(sizeof(Particle) * iNumParticles);

       for(i=0; i<iNumParticles; i++) // init particles
       {
              pParticles[i].fPosX = 0;
              pParticles[i].fPosY = 0;
              pParticles[i].fVelX = 0;
              pParticles[i].fVelY = 0;
              pParticles[i].fRotVel = 0;
              pParticles[i].fSize = .01;
              pParticles[i].bAlive = true;
              pParticles[i].fAngle = 0;
              pParticles[i].fEnergy = 1;
       }

       fRandomness = 0;
       fDecayRate = 0;
       fColorR = 1; // set default color to white
       fColorG = 1;
       fColorB = 1;
}


PSystem::PSystem(Vector vPos, Vector vFce, float fSAngle, float fFric, float fRand, int iParticles)
{
       int i;
       Vector vTemp;
       float angle1, angle2;

       vPosition = vPos;
       vForce = vFce;
       
       fSpreadAngle = fSAngle;
       fFriction = fFric;
       iNumParticles = iParticles;

       fColorR = 1; // set default color to white
       fColorG = 1;
       fColorB = 1;

       angle1 = -(fSAngle/2);

       if(iNumParticles > MAX_PARTICLES) { iNumParticles = MAX_PARTICLES; } // limit particles

       pParticles = (Particle *) malloc(sizeof(Particle) * iNumParticles); // reserve memory

       for(i=0; i<iNumParticles; i++) // init particles
       {
              fRandomness = fRand;
              fDecayRate = 0.1;

              vTemp = vForce;
              vTemp *= 1 + ((float)(rand()%100) -50) / 100 * fRandomness;
              angle2 = angle1 + ((float) i/ (float) iNumParticles) * fSpreadAngle;
              vTemp = VRotate2D(angle2 + ((float)(rand()%100) -50) / 100 * fRandomness, vTemp);

              pParticles[i].fPosX = vPos.x;
              pParticles[i].fPosY = vPos.y;
              pParticles[i].fVelX = vTemp.x;
              pParticles[i].fVelY = vTemp.y;
              pParticles[i].fSize = .1 + ((float)(rand()%100) - 50) / 100 * 3.5;
              pParticles[i].bAlive = true;
              pParticles[i].fAngle = 0;
              pParticles[i].fEnergy = 2;
              pParticles[i].fDecayRate = fDecayRate + (((float)(rand()%100)) / 100) * .1;

              pParticles[i].fRotVel = ((float)(rand()%100) -50) / 100 * 0.1;
       }
}


PSystem::~PSystem(void)
{
       free(pParticles); // free memory reserved for particles
}


bool PSystem::Step(float timeStep)
{
       int i;
       bool someAlive = false; // still some particles with energy

       for(i=0; i<iNumParticles; i++)
       {
              if(pParticles[i].fEnergy <= 0)
              {
                     pParticles[i].bAlive = false;
                     continue; // done with this particle
              }

              pParticles[i].fVelX *= 1 / fFriction;
              pParticles[i].fVelY *= 1 / fFriction;

              pParticles[i].fPosX += (pParticles[i].fVelX * timeStep);
              pParticles[i].fPosY += (pParticles[i].fVelY * timeStep);

              pParticles[i].fAngle += pParticles[i].fRotVel;

              pParticles[i].fEnergy -= fDecayRate;

              someAlive = true; // at least this particle is still alive
       }
       
       if(someAlive == false) // no particles left alive
       {
              return true; // expired
       }
       else
       {
              return false; // not expired yet
       }
}

void PSystem::Draw(void)
{
       int i;
       
       glBlendFunc (GL_SRC_ALPHA, GL_ONE);
       glEnable (GL_BLEND);
       glDisable(GL_TEXTURE_2D);

       glPushMatrix();
       glTranslatef(0,0,.1);

       for(i=0; i<iNumParticles; i++)
       {
              glPushMatrix();
              glTranslatef(pParticles[i].fPosX, pParticles[i].fPosY,.5);
              glRotatef(pParticles[i].fAngle,0,0,1);
              glScalef(pParticles[i].fSize, pParticles[i].fSize, 1);
              glColor4f(fColorR, fColorG, fColorB, pParticles[i].fEnergy);
              glBegin(GL_TRIANGLES);
              glVertex2f(0.0, 0.1);
              glVertex2f(-0.1, -0.1);
              glVertex2f(0.1, -0.1);
              glEnd();
              glPopMatrix();
       }
       glPopMatrix();
}


void PSystem::SetColor(float r, float g, float b)
{
       fColorR = r;
       fColorG = g;
       fColorB = b;
}

 

Copyright Windsor Schmidt 2006 - All rights reserved.