renamed *_SPRITE to *, made rocks bounce off each other.

[vor.git] / sprite.c

diff --git a/sprite.c b/sprite.c
index 45cd0f9..1905510 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; }
                }
@@ -197,6 +198,8 @@ collide(Sprite *a, Sprite *b)
 {
        int dx, dy, xov, yov;
 
+       if(a->type < 0 || b->type < 0) return false;
+
        if(b->x < a->x) { Sprite *tmp = a; a = b; b = tmp; }
 
        dx = b->x - a->x;
@@ -205,12 +208,23 @@ collide(Sprite *a, Sprite *b)
        xov = max(min(a->w - dx, b->w), 0);
 
        if(dy >= 0) yov = max(min(a->h - dy, b->h), 0);
-       else yov = -max(min(a->h - -dy, b->h), 0);
+       else yov = -max(min(b->h - -dy, a->h), 0);
 
        if(xov == 0 || yov == 0) return false;
        else return mask_collide(xov, yov, a, b);
 }
 
+void
+collisions(void)
+{
+       int i;
+       Sprite *a, *b;
+       for(i=0; i<gw*gh; i++)
+               for(a=sprites[set][i]; a; a=a->next)
+                       for(b=a->next; b; b=b->next)
+                               if(collide(a, b)) do_collision(a, b);
+}
+
 Sprite *
 hit_in_square(Sprite *r, Sprite *s)
 {
@@ -285,19 +299,35 @@ pixel_collides(float x, float y)
        return false;
 }
 
+
+static 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;
+       float ma, mb, mr;
 
+       // (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 = 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;
 
-       a->dx += x*(nb-na); a->dy += y*(nb-na);
-       b->dx += x*(na-nb); b->dy += y*(na-nb);
+       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;
 }