particle.c

   1 #include "particle.h"
   2
   3 double b_x1, b_y1, b_x2, b_y2;
   4
   5 typedef struct plistitem_s{
   6         Particle *p;
   7 }plistitem_t;
   8
   9 #define NO_PARTS 100
  10 plistitem_t parts[NO_PARTS];
  11
  12 void SetParticleBoundingBox(double x, double y, double xx, double yy)
  13 {
  14         b_x1 = x;
  15         b_y1 = y;
  16         b_x2 = x + xx;
  17         b_y2 = y + yy;
  18 }
  19
  20 void AddParticle(Particle *p)
  21 {
  22         int i;
  23
  24         for (i = 0; i < NO_PARTS; i++) {
  25                 if (parts[i].p == 0) {
  26                         parts[i].p = p;
  27                         return;
  28                 };
  29         };
  30         free(p);
  31 }
  32
  33 void UpdateParticle(Particle *p, double dt)
  34 {
  35         p->x = p->x + dt * p->vx;
  36         p->vx = p->vx * (1.0 - p->fx*dt) + dt * p->ax;
  37         p->y = p->y + dt * p->vy;
  38         p->vy = p->vy * (1.0 - p->fy*dt) + dt * p->ay;
  39         p->t = p->t + dt * p->vt;
  40         p->vt = p->vt * (1.0 - p->ft*dt) + dt * p->at;
  41 }
  42
  43 void WhiteFunc(double temp, SDL_Color *c)
  44 {
  45         static SDL_Color white={255,255,255,255};
  46         if (c != 0) memcpy(c, &white, sizeof(SDL_Color));
  47 }
  48
  49 void QueueDrawPart(Particle *p)
  50 {
  51         SDL_Color color;
  52
  53         if (p->tf != 0){
  54                 p->tf(p->t, &color);
  55         }else{
  56                 WhiteFunc(p->t, &color);
  57         };
  58         QueueDrawSpriteColorize(p->s, p->x, p->y, p->z, color);
  59 }
  60
  61 void RemoveParticle(plistitem_t *a)
  62 {
  63         if (a == 0) return;
  64         if (a->p)free(a->p);
  65         a->p = 0;
  66 }
  67
  68 void UpdateAndQueueDrawParticles(double dt)
  69 {
  70         plistitem_t *a;
  71         int i;
  72         for (i=0; i<NO_PARTS; i++){
  73                 a = &parts[i];
  74                 if (a->p == 0){
  75                         continue;
  76                 };
  77
  78                 UpdateParticle(a->p, dt);
  79
  80                 if (a->p->t <= 0.0 || a->p->x < b_x1 || a->p->y < b_y1 || (a->p->x + a->p->s->width) > b_x2 || (a->p->x + a->p->s->width) > b_x2) {
  81                         RemoveParticle(a);
  82                         continue;
  83                 };
  84
  85                 QueueDrawPart(a->p);
  86         };
  87 }