proper moving-away detection in bounce()?

[vor.git] / sprite.c

diff --git a/sprite.c b/sprite.c
index a772668..1a35a6a 100644 (file)
--- a/sprite.c
+++ b/sprite.c
@@ -33,6 +33,7 @@ get_shape(Sprite *s)
        uint16_t *px, transp;
        uint32_t bits = 0, bit, *p;
 
+       s->area = 0;
        if(s->image->format->BytesPerPixel != 2) {
                fprintf(stderr, "get_shape(): not a 16-bit image!\n");
                exit(1);
@@ -55,7 +56,7 @@ get_shape(Sprite *s)
                bit = 0;
                for(x=0; x<s->image->w; x++) {
                        if(!bit) { bits = 0; bit = 0x80000000; }
-                       if(*px++ != transp) { bits |= bit; }
+                       if(*px++ != transp) { bits |= bit; s->area++; }
                        bit >>= 1;
                        if(!bit || x == s->image->w - 1) { *(p++) = bits; }
                }
@@ -114,11 +115,25 @@ add_sprite(Sprite *s)
 }
 
 void
+reset_sprites(void)
+{
+       int i;
+
+       for(i=0; i<gw*gh; i++)
+               while(sprites[set][i]) {
+                       Sprite *s = remove_sprite(&sprites[set][i]);
+                       insert_sprite(&free_sprites[s->type], s);
+                       s->flags = 0;
+               }
+}
+
+void
 move_sprite(Sprite *s)
 {
-       // move it.
-       s->x += (s->dx - screendx)*t_frame;
-       s->y += (s->dy - screendy)*t_frame;
+       if(s->flags & MOVE) {
+               s->x += (s->dx - screendx)*t_frame;
+               s->y += (s->dy - screendy)*t_frame;
+       }
 }
 
 void
@@ -128,7 +143,7 @@ sort_sprite(Sprite *s)
        if(s->x + s->w < 0 || s->x >= XSIZE
           || s->y + s->h < 0 || s->y >= YSIZE) {
                insert_sprite(&free_sprites[s->type], s);
-               s->type = NONE;
+               s->flags = 0;
        } else insert_sprite(square(s->x, s->y, 1-set), s);
 }
 
@@ -138,7 +153,7 @@ move_sprites(void)
        int sq;
        Sprite **head;
 
-       // Move all the sprites (position and set)
+       // Move all the sprites
        for(sq=0; sq<gw*gh; sq++) {
                head=&sprites[set][sq];
                while(*head) {
@@ -197,6 +212,8 @@ collide(Sprite *a, Sprite *b)
 {
        int dx, dy, xov, yov;
 
+       if(!COLLIDES(a) || !COLLIDES(b)) return false;
+
        if(b->x < a->x) { Sprite *tmp = a; a = b; b = tmp; }
 
        dx = b->x - a->x;
@@ -211,6 +228,28 @@ collide(Sprite *a, Sprite *b)
        else return mask_collide(xov, yov, a, b);
 }
 
+void
+collide_with_list(Sprite *s, Sprite *list)
+{
+       for(; list; list=list->next)
+               if(collide(s, list)) do_collision(s, list);
+}
+
+void
+collisions(void)
+{
+       int i, end = gw*gh;
+       Sprite *s;
+       for(i=0; i<end; i++) {
+               for(s=sprites[set][i]; s; s=s->next) {
+                       collide_with_list(s, s->next);
+                       if(i+1 < end) collide_with_list(s, sprites[set][i+1]);
+                       if(i+gw < end) collide_with_list(s, sprites[set][i+gw]);
+                       if(i+gw+1 < end) collide_with_list(s, sprites[set][i+gw+1]);
+               }
+       }
+}
+
 Sprite *
 hit_in_square(Sprite *r, Sprite *s)
 {
@@ -253,6 +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;
 
@@ -261,43 +302,60 @@ 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(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;
+}
+
+
+float
+sprite_mass(Sprite *s)
+{
+       if(s->type == SHIP) return s->area;
+       else if(s->type == ROCK) return 3 * s->area;
+       else return 0;
 }
 
 void
 bounce(Sprite *a, Sprite *b)
 {
        float x, y, n;
-       float na, nb;
+       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);
        y = (b->y + b->h / 2) - (a->y + a->h / 2);
        n = sqrt(x*x + y*y); x /= n; y /= n;
 
-       na = (x*a->dx + y*a->dy); // sqrt(a->dx*a->dx + a->dy*a->dy);
-       nb = (x*b->dx + y*b->dy); // sqrt(b->dx*b->dx + b->dy*b->dy);
+       // velocities along (x, y), or 0 if already moving away.
+       va = x*a->dx + y*a->dy;
+       vb = x*b->dx + y*b->dy;
+       if(vb-va > 0) return;
+
+       ma = sprite_mass(a); mb = sprite_mass(b);
+       vc = (va*ma + vb*mb) / (ma+mb);
 
-       a->dx += x*(nb-na); a->dy += y*(nb-na);
-       b->dx += x*(na-nb); b->dy += y*(na-nb);
+       a->dx += 2*x*(vc-va); a->dy += 2*y*(vc-va);
+       b->dx += 2*x*(vc-vb); b->dy += 2*y*(vc-vb);
 }