sucks, maybe I should try integer rasterization with error accumulation...

[dosdemo] / src / polyfill.c

diff --git a/src/polyfill.c b/src/polyfill.c
index d8facb5..7bffaa3 100644 (file)
--- a/src/polyfill.c
+++ b/src/polyfill.c
@@ -1,14 +1,20 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <alloca.h>
 #include "polyfill.h"
 #include "gfxutil.h"
 #include "demo.h"
 
 void (*fillfunc[])(struct pvertex*, int) = {
        polyfill_wire,
-       0, 0, 0, 0
+       polyfill_flat,
+       0, 0, 0
 };
 
+struct pimage pimg_fb, pimg_texture;
+
 void polyfill(int mode, struct pvertex *verts, int nverts)
 {
 #ifndef NDEBUG
@@ -23,19 +29,106 @@ void polyfill(int mode, struct pvertex *verts, int nverts)
 
 void polyfill_wire(struct pvertex *verts, int nverts)
 {
-       int i;
+       int i, x0, y0, x1, y1;
        struct pvertex *v = verts;
        unsigned short color = ((v->r << 8) & 0xf800) |
                ((v->g << 3) & 0x7e0) | ((v->b >> 3) & 0x1f);
 
-       for(i=0; i<nverts; i++) {
-               int x0, y0, x1, y1;
+       for(i=0; i<nverts - 1; i++) {
                x0 = v->x >> 8;
                y0 = v->y >> 8;
                ++v;
                x1 = v->x >> 8;
                y1 = v->y >> 8;
-               clip_line(&x0, &y0, &x1, &y1, 0, 0, fb_width, fb_height);
-               draw_line(x0, y0, x1, y1, color);
+               if(clip_line(&x0, &y0, &x1, &y1, 0, 0, pimg_fb.width, pimg_fb.height)) {
+                       draw_line(x0, y0, x1, y1, color);
+               }
+       }
+       x0 = verts[0].x >> 8;
+       y0 = verts[0].y >> 8;
+       if(clip_line(&x1, &y1, &x0, &y0, 0, 0, pimg_fb.width, pimg_fb.height)) {
+               draw_line(x1, y1, x0, y0, color);
+       }
+}
+
+static void scan_edge(struct pvertex *v0, struct pvertex *v1, struct pvertex *edge);
+
+#define NEXTIDX(x) (((x) - 1 + nverts) % nverts)
+#define PREVIDX(x) (((x) + 1) % nverts)
+
+void polyfill_flat(struct pvertex *pv, int nverts)
+{
+       int i;
+       int32_t y;
+       int topidx = 0, botidx = 0, sline;
+       struct pvertex *left, *right;
+       /*uint16_t color = PACK_RGB16(pv[0].r, pv[0].g, pv[0].b);*/
+
+       for(i=1; i<nverts; i++) {
+               if(pv[i].y < pv[topidx].y) topidx = i;
+               if(pv[i].y > pv[botidx].y) botidx = i;
+       }
+
+       left = (struct pvertex*)alloca(pimg_fb.height * sizeof *left);
+       right = (struct pvertex*)alloca(pimg_fb.height * sizeof *right);
+       memset(left, 0, pimg_fb.height * sizeof *left);
+       memset(right, 0, pimg_fb.height * sizeof *right);
+
+       for(i=0; i<nverts; i++) {
+               int next = NEXTIDX(i);
+               int32_t y0 = pv[i].y;
+               int32_t y1 = pv[next].y;
+
+               if((y0 >> 8) == (y1 >> 8)) {
+                       if(y0 > y1) {
+                               int idx = y0 >> 8;
+                               left[idx].x = pv[i].x < pv[next].x ? pv[i].x : pv[next].x;
+                               right[idx].x = pv[i].x < pv[next].x ? pv[next].x : pv[i].x;
+                       }
+               } else {
+                       scan_edge(pv + i, pv + next, y0 > y1 ? left : right);
+               }
+       }
+
+       y = pv[topidx].y;
+       while(y < pv[botidx].y) {
+               int32_t x;
+               uint16_t *pixptr;
+
+               sline = y >> 8;
+               x = left[sline].x;
+
+               pixptr = pimg_fb.pixels + sline * pimg_fb.width + (x >> 8);
+
+               while(x <= right[sline].x) {
+                       *pixptr++ += 15;
+                       x += 256;
+               }
+               y += 256;
+       }
+}
+
+static void scan_edge(struct pvertex *v0, struct pvertex *v1, struct pvertex *edge)
+{
+       int32_t x, y, dx, dy, slope;
+       int idx;
+
+       if(v0->y > v1->y) {
+               struct pvertex *tmp = v0;
+               v0 = v1;
+               v1 = tmp;
+       }
+
+       dy = v1->y - v0->y;
+       dx = v1->x - v0->x;
+       slope = (dx << 8) / dy;
+       idx = v0->y >> 8;
+
+       x = v0->x;
+       y = v0->y;
+       while(y <= v1->y) {
+               edge[idx++].x = x;
+               x += slope;
+               y += 256;
        }
 }