-
-
-
-int init_emitter(struct emitter *em, int num, unsigned char *map, int xsz, int ysz)
-{
- int i, x, y;
- float aspect = (float)xsz / (float)ysz;
- struct particle *p;
-
- if(!(em->plist = malloc(num * sizeof *em->plist))) {
- return -1;
- }
- em->pcount = num;
-
- p = em->plist;
- for(i=0; i<num; i++) {
- do {
- x = rand() % xsz;
- y = rand() % ysz;
- } while(map[y * xsz + x] < 128);
-
- p->x = (float)x / (float)xsz - 0.5;
- p->y = -(float)y / (float)xsz + 0.5 / aspect;
- p->z = ((float)i / (float)num * 2.0 - 1.0) * 0.005;
- p->r = p->g = p->b = 255;
- p->vx = p->vy = p->vz = 0.0f;
- p->life = MAX_LIFE;
- ++p;
- }
- return 0;
-}
-
-void update_particles(struct emitter *em, float dt)
-{
- int i;
- struct vec2 accel;
- struct particle *p = em->plist;
- struct g3d_vertex *v = varr;
-
- for(i=0; i<em->pcount; i++) {
- vfield_eval(&vfield, p->x, p->y, &accel);
- p->x += p->vx * DRAG * dt;
- p->y += p->vy * DRAG * dt;
- p->z += p->vz * DRAG * dt;
- p->vx += (wind[0] + accel.x * FORCE) * dt;
- p->vy += (wind[1] + accel.y * FORCE) * dt;
- p->vz += (wind[2] + p->z * ZBIAS) * dt;
- p->life -= dt;
- if(p->life < 0.0f) p->life = 0.0f;
-
- v->x = p->x;
- v->y = p->y;
- v->z = p->z;
- v->w = 1.0f;
- v->a = cround64(p->life * 255.0 / MAX_LIFE);
- v->r = 0;
- v->g = (v->a & 0xe0) >> 3;
- v->b = (v->a & 0x1f) << 3;
- ++v;
-
- ++p;
- }
-}
-
-void draw_particles(struct emitter *em)
-{
- g3d_draw(G3D_POINTS, varr, PCOUNT);
-}
-
-
-int init_vfield_load(struct vfield *vf, const char *fname)
-{
- FILE *fp;
- int tmp;
-
- if(!(fp = fopen(fname, "rb"))) {
- fprintf(stderr, "failed to open vector field: %s\n", fname);
- return -1;
- }
- if(fread(&vf->width, sizeof vf->width, 1, fp) < 1 ||
- fread(&vf->height, sizeof vf->height, 1, fp) < 1) {
- fprintf(stderr, "init_vfield_load: unexpected end of file while reading header\n");
- fclose(fp);
- return -1;
- }
-
- /* assume xsz is pow2 otherwise fuck you */
- tmp = vf->width - 1;
- vf->xshift = 0;
- while(tmp) {
- ++vf->xshift;
- tmp >>= 1;
- }
-
- if(!(vf->v = malloc(vf->width * vf->height * sizeof *vf->v))) {
- fprintf(stderr, "failed to allocate %dx%d vector field\n", vf->width, vf->height);
- fclose(fp);
- return -1;
- }
- if(fread(vf->v, sizeof *vf->v, vf->width * vf->height, fp) < vf->width * vf->height) {
- fprintf(stderr, "init_vfield_load: unexpected end of file while reading %dx%d vector field\n",
- vf->width, vf->height);
- fclose(fp);
- return -1;
- }
- fclose(fp);
-
- vf->pos.x = vf->pos.y = 0;
- vf->size.x = vf->size.y = 1;
- return 0;
-}
-
-void vfield_eval(struct vfield *vf, float x, float y, struct vec2 *dir)
-{
- int px, py;
- float tx, ty;
- struct vec2 *p1, *p2;
- struct vec2 left, right;
-
- x = ((x - vf->pos.x) / vf->size.x + 0.5f) * vf->width;
- y = ((y - vf->pos.y) / vf->size.y + 0.5f) * vf->height;
- x = floor(x);
- y = floor(y);
-
- if(x < 0) x = 0;
- if(y < 0) y = 0;
- if(x > vf->width - 2) x = vf->width - 2;
- if(y > vf->height - 2) y = vf->height - 2;
-
- px = (int)x;
- py = (int)y;
-
- p1 = vf->v + (py << vf->xshift) + px;
-#ifdef BILERP_FIELD
- p2 = p1 + vf->width;
-
- tx = fmod(x, 1.0f);
- ty = fmod(y, 1.0f);
-
- left.x = p1->x + (p2->x - p1->x) * ty;
- left.y = p1->y + (p2->y - p1->y) * ty;
- ++p1;
- ++p2;
- right.x = p1->x + (p2->x - p1->x) * ty;
- right.y = p1->y + (p2->y - p1->y) * ty;
-
- dir->x = left.x + (right.x - left.x) * tx;
- dir->y = left.y + (right.y - left.y) * ty;
-#else
- dir->x = p1->x;
- dir->y = p1->y;
-#endif
-
-#ifdef RANDOMIZE_FIELD
- dir->x += ((float)rand() / RAND_MAX - 0.5) * RAND_FIELD_MAX;
- dir->y += ((float)rand() / RAND_MAX - 0.5) * RAND_FIELD_MAX;
-#endif
-}