X-Git-Url: https://jasonwoof.com/gitweb/?p=vor.git;a=blobdiff_plain;f=sprite.c;h=1a35a6a16266a6c3fb4b0db34c86d31063c30988;hp=aadf22d878fa42dea90d17cdca3bf5f88644e4d5;hb=37b3a2e06abc694205e843a573c4bb2eaaabb730;hpb=45925ff114a17b9c1c0a720ff668e2cb795cd761

diff --git a/sprite.c b/sprite.c
index aadf22d..1a35a6a 100644
--- a/sprite.c
+++ b/sprite.c
@@ -292,6 +292,8 @@ int
 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;
 
@@ -300,36 +302,37 @@ pixel_collide(Sprite *s, int x, int y)
 	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;
 }
 
@@ -337,8 +340,8 @@ void
 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);
@@ -346,13 +349,13 @@ bounce(Sprite *a, Sprite *b)
 	n = sqrt(x*x + y*y); x /= n; y /= n;
 
 	// velocities along (x, y), or 0 if already moving away.
-	va = max(x*a->dx + y*a->dy, 0);
-	vb = min(x*b->dx + y*b->dy, 0);
+	va = x*a->dx + y*a->dy;
+	vb = x*b->dx + y*b->dy;
+	if(vb-va > 0) return;
 
-	// 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);
 }