progs/demos/particles.cxx

   1 /*
   2  * This program is under the GNU GPL.
   3  * Use at your own risk.
   4  *
   5  * written by David Bucciarelli (humanware@plus.it)
   6  *            Humanware s.r.l.
   7  */
   8
   9 #include <stdlib.h>
  10
  11 #include "particles.h"
  12
  13 #define vinit(a,i,j,k) {\
  14   (a)[0]=i;\
  15   (a)[1]=j;\
  16   (a)[2]=k;\
  17 }
  18
  19 #define vadds(a,dt,b) {\
  20   (a)[0]+=(dt)*(b)[0];\
  21   (a)[1]+=(dt)*(b)[1];\
  22   (a)[2]+=(dt)*(b)[2];\
  23 }
  24
  25 #define vequ(a,b) {\
  26   (a)[0]=(b)[0];\
  27   (a)[1]=(b)[1];\
  28   (a)[2]=(b)[2];\
  29 }
  30
  31 #define vinter(a,dt,b,c) {\
  32   (a)[0]=(dt)*(b)[0]+(1.0-dt)*(c)[0];\
  33   (a)[1]=(dt)*(b)[1]+(1.0-dt)*(c)[1];\
  34   (a)[2]=(dt)*(b)[2]+(1.0-dt)*(c)[2];\
  35 }
  36
  37 #define clamp(a)        ((a) < 0.0 ? 0.0 : ((a) < 1.0 ? (a) : 1.0))
  38
  39 #define vclamp(v) {\
  40   (v)[0]=clamp((v)[0]);\
  41   (v)[1]=clamp((v)[1]);\
  42   (v)[2]=clamp((v)[2]);\
  43 }
  44
  45
  46 float rainParticle::min[3];
  47 float rainParticle::max[3];
  48 float rainParticle::partLength=0.2f;
  49
  50
  51 static float vrnd(void)
  52 {
  53   return(((float)rand())/RAND_MAX);
  54 }
  55
  56
  57 particle::particle()
  58 {
  59   age=0.0f;
  60
  61   vinit(acc,0.0f,0.0f,0.0f);
  62   vinit(vel,0.0f,0.0f,0.0f);
  63   vinit(pos,0.0f,0.0f,0.0f);
  64 }
  65
  66 void particle::elapsedTime(float dt)
  67 {
  68   age+=dt;
  69
  70   vadds(vel,dt,acc);
  71
  72   vadds(pos,dt,vel);
  73 }
  74
  75 /////////////////////////////////////////
  76 // Particle System
  77 /////////////////////////////////////////
  78
  79 particleSystem::particleSystem()
  80 {
  81   t=0.0f;
  82
  83   part=NULL;
  84
  85   particleNum=0;
  86 }
  87
  88 particleSystem::~particleSystem()
  89 {
  90   if(part)
  91     free(part);
  92 }
  93
  94 void particleSystem::addParticle(particle *p)
  95 {
  96   if(!part) {
  97     part=(particle **)calloc(1,sizeof(particle *));
  98     part[0]=p;
  99     particleNum=1;
 100   } else {
 101     particleNum++;
 102     part=(particle **)realloc(part,sizeof(particle *)*particleNum);
 103     part[particleNum-1]=p;
 104   }
 105 }
 106
 107 void particleSystem::reset(void)
 108 {
 109   if(part)
 110     free(part);
 111
 112   t=0.0f;
 113
 114   part=NULL;
 115
 116   particleNum=0;
 117 }
 118
 119 void particleSystem::draw(void)
 120 {
 121   if(!part)
 122     return;
 123
 124   part[0]->beginDraw();
 125   for(unsigned int i=0;i<particleNum;i++)
 126     part[i]->draw();
 127   part[0]->endDraw();
 128 }
 129
 130 void particleSystem::addTime(float dt)
 131 {
 132   if(!part)
 133     return;
 134
 135   for(unsigned int i=0;i<particleNum;i++) {
 136     part[i]->elapsedTime(dt);
 137     part[i]->checkAge();
 138   }
 139 }
 140
 141 /////////////////////////////////////////
 142 // Rain
 143 /////////////////////////////////////////
 144
 145 void rainParticle::init(void)
 146 {
 147   age=0.0f;
 148
 149   acc[0]=0.0f;
 150   acc[1]=-0.98f;
 151   acc[2]=0.0f;
 152
 153   vel[0]=0.0f;
 154   vel[1]=0.0f;
 155   vel[2]=0.0f;
 156
 157   oldpos[0]=pos[0]=min[0]+(max[0]-min[0])*vrnd();
 158   oldpos[1]=pos[1]=max[1]+0.2f*max[1]*vrnd();
 159   oldpos[2]=pos[2]=min[2]+(max[2]-min[2])*vrnd();
 160
 161   vadds(oldpos,-partLength,vel);
 162 }
 163
 164 rainParticle::rainParticle()
 165 {
 166   init();
 167 }
 168
 169 void rainParticle::setRainingArea(float minx, float miny, float minz,
 170                                   float maxx, float maxy, float maxz)
 171 {
 172   vinit(min,minx,miny,minz);
 173   vinit(max,maxx,maxy,maxz);
 174 }
 175
 176 void rainParticle::setLength(float l)
 177 {
 178   partLength=l;
 179 }
 180
 181 void rainParticle::draw(void)
 182 {
 183   glColor4f(0.7f,0.95f,1.0f,0.0f);
 184   glVertex3fv(oldpos);
 185
 186   glColor4f(0.3f,0.7f,1.0f,1.0f);
 187   glVertex3fv(pos);
 188 }
 189
 190 void rainParticle::checkAge(void)
 191 {
 192   if(pos[1]<min[1])
 193     init();
 194 }
 195
 196 void rainParticle::elapsedTime(float dt)
 197 {
 198   particle::elapsedTime(dt);
 199
 200   if(pos[0]<min[0])
 201     pos[0]=max[0]-(min[0]-pos[0]);
 202   if(pos[2]<min[2])
 203     pos[2]=max[2]-(min[2]-pos[2]);
 204
 205   if(pos[0]>max[0])
 206     pos[0]=min[0]+(pos[0]-max[0]);
 207   if(pos[2]>max[2])
 208     pos[2]=min[2]+(pos[2]-max[2]);
 209
 210   vequ(oldpos,pos);
 211   vadds(oldpos,-partLength,vel);
 212 }
 213
 214 void rainParticle::randomHeight(void)
 215 {
 216   pos[1]=(max[1]-min[1])*vrnd()+min[1];
 217
 218   oldpos[1]=pos[1]-partLength*vel[1];
 219 }