void
move_sprite(Sprite *s)
{
- if(s->flags & DRAW_FLAG) {
- // move it.
+ if(s->flags & MOVE) {
s->x += (s->dx - screendx)*t_frame;
s->y += (s->dy - screendy)*t_frame;
}
pixel_collide(Sprite *s, int x, int y)
{
uint32_t pmask;
+
+ if(!COLLIDES(s)) return false;
if(x < s->x || y < s->y || x >= s->x + s->w || y >= s->y + s->h) return 0;
return s->mask[(y*s->mask_w) + (x>>5)] & pmask;
}
-int
+Sprite *
pixel_hit_in_square(Sprite *r, float x, float y)
{
for(; r; r=r->next) {
- if(COLLIDES(r) && pixel_collide(r, x, y)) return 1;
+ if(COLLIDES(r) && pixel_collide(r, x, y)) return r;
}
return 0;
}
-int
+Sprite *
pixel_collides(float x, float y)
{
int l, t;
Sprite **sq;
+ Sprite *ret;
l = (x + grid_size) / grid_size; t = (y + grid_size) / grid_size;
sq = &sprites[set][l + t*gw];
- if(pixel_hit_in_square(*sq, x, y)) return true;
- if(l > 0 && pixel_hit_in_square(*(sq-1), x, y)) return true;
- if(t > 0 && pixel_hit_in_square(*(sq-gw), x, y)) return true;
- if(l > 0 && t > 0 && pixel_hit_in_square(*(sq-1-gw), x, y)) return true;
- return false;
+ if((ret = pixel_hit_in_square(*sq, x, y))) return ret;
+ if(l > 0 && (ret = pixel_hit_in_square(*(sq-1), x, y))) return ret;
+ if(t > 0 && (ret = pixel_hit_in_square(*(sq-gw), x, y))) return ret;
+ if(l > 0 && t > 0 && (ret = pixel_hit_in_square(*(sq-1-gw), x, y))) return ret;
+ return 0;
}
-static float
+float
sprite_mass(Sprite *s)
{
if(s->type == SHIP) return s->area;
- else if(s->type == ROCK) return 3*s->area;
+ else if(s->type == ROCK) return 3 * s->area;
else return 0;
}
bounce(Sprite *a, Sprite *b)
{
float x, y, n;
- float va, vb;
- float ma, mb, mr;
+ float va, vb, vc;
+ float ma, mb;
// (x, y) is unit vector pointing from A's center to B's center.
x = (b->x + b->w / 2) - (a->x + a->w / 2);
va = max(x*a->dx + y*a->dy, 0);
vb = min(x*b->dx + y*b->dy, 0);
- // mass ratio
ma = sprite_mass(a); mb = sprite_mass(b);
- if(ma && mb) mr = mb/ma; else mr = 1;
+ vc = (va*ma + vb*mb) / (ma+mb);
- a->dx += x*(mb*vb - ma*va)/ma; a->dy += y*(mb*vb - ma*va)/ma;
- b->dx += x*(ma*va - mb*vb)/mb; b->dy += y*(ma*va - mb*vb)/mb;
+ a->dx += 2*x*(vc-va); a->dy += 2*y*(vc-va);
+ b->dx += 2*x*(vc-vb); b->dy += 2*y*(vc-vb);
}