By Jove, I think I've got it!

[vor.git] / shape.c

diff --git a/shape.c b/shape.c
index 92914cb..867610e 100644 (file)
--- a/shape.c
+++ b/shape.c
@@ -6,7 +6,7 @@ get_shape(SDL_Surface *img, struct shape *s)
 {
        int x, y;
        uint16_t *px, transp;
-       uint32_t bits;
+       uint32_t bits, bit, *p;
 
        if(img->format->BytesPerPixel != 2) {
                fprintf(stderr, "get_shape(): not a 16-bit image!\n");
@@ -14,8 +14,8 @@ get_shape(SDL_Surface *img, struct shape *s)
        }
 
        s->w = img->w; s->h = img->h;
-       s->mw = ((img->w+31)>>5) * img->h;
-       s->mask = malloc(4*s->mw);
+       s->mw = ((img->w+31)>>5);
+       s->mask = malloc(4*s->mw*s->h);
        if(!s->mask) {
                fprintf(stderr, "can't malloc bitmask");
                exit(1);
@@ -24,14 +24,14 @@ get_shape(SDL_Surface *img, struct shape *s)
        SDL_LockSurface(img);
        px = img->pixels;
        transp = img->format->colorkey;
-       bits = 0;
+       p = s->mask;
        for(y=0; y<img->h; y++) {
+               bit = 0;
                for(x=0; x<img->w; x++) {
-                       if(*px++ != transp) bits |= 1;
-                       if(x == img->w-1 || !(x+1)%32) {
-                               *(s->mask++) = bits;
-                               bits = 0;
-                       } else bits = bits << 1;
+                       if(!bit) { bits = 0; bit = 0x80000000; }
+                       if(*px++ != transp) bits |= bit;
+                       bit >>= 1;
+                       if(!bit || x == img->w - 1) { *(p++) = bits; }
                }
                px = (uint16_t *) ((uint8_t *) px + img->pitch - 2*img->w);
        }
@@ -46,6 +46,64 @@ get_shape(SDL_Surface *img, struct shape *s)
 #define min(a, b) ((a) < (b) ? (a) : (b))
 #endif
 
+#ifndef abs
+#define abs(a) ((a)<=0 ? -(a) : (a))
+#endif
+
+int
+line_collide(int xov, struct shape *r, uint32_t *rbits, struct shape *s, uint32_t *sbits)
+{
+       int lshift, n, i, ret = 0;
+       uint32_t lbits;
+       struct shape *st;
+       uint32_t *bt;
+
+
+       if(xov < 0) {
+               st = r; r = s; s = st;
+               bt = rbits; rbits = sbits; sbits = bt;
+               xov = -xov;
+       }
+
+
+       lshift = (r->w - xov) & 31; 
+       rbits += (r->w - xov) >> 5;
+       n = (xov + 31) >> 5;
+       for(i=0; i<n-1; i++) {
+               lbits = *rbits++ << lshift;
+               lbits |= *rbits >> (32 - lshift);
+               if(lbits & *sbits++) ret = 1;
+       }
+       lbits = *rbits << lshift;
+       if(lbits & *sbits) ret = 1;
+
+       return ret;
+}
+
+int
+mask_collide(int xov, int yov, struct shape *r, struct shape *s)
+{
+       int y, ry, sy;
+       uint32_t *rbits, *sbits;
+
+       if(yov > 0) {
+               ry = r->h - yov; sy = 0;
+               rbits = r->mask + (r->h - yov) * r->mw;
+               sbits = s->mask;
+       } else {
+               ry = 0; sy = s->h + yov;
+               rbits = r->mask;
+               sbits = s->mask + (s->h + yov) * s->mw;
+       }
+
+       for(y=0; y<abs(yov); y++) {
+               if(line_collide(xov, r, rbits, s, sbits)) return 1;
+               rbits += r->mw; sbits += s->mw;
+       }
+
+       return 0;
+}
+
 int
 collide(int xdiff, int ydiff, struct shape *r, struct shape *s)
 {
@@ -58,5 +116,5 @@ collide(int xdiff, int ydiff, struct shape *r, struct shape *s)
        else yov = min(-min(s->h+ydiff, r->h), 0);
 
        if(xov == 0 || yov == 0) return 0;  // bboxes hit?
-       else return 1;
+       else return mask_collide(xov, yov, r, s);
 }