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

diff --git a/src/polyfill.c b/src/polyfill.c
index 79d1d69..7bffaa3 100644 (file)
--- a/src/polyfill.c
+++ b/src/polyfill.c
@@ -1,5 +1,8 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <alloca.h>
 #include "polyfill.h"
 #include "gfxutil.h"
 #include "demo.h"
@@ -48,82 +51,84 @@ void polyfill_wire(struct pvertex *verts, int nverts)
        }
 }
 
+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)
 
-#define CALC_EDGE(which) \
-       do { \
-               which##_x = pv[which##_beg].x; \
-               which##_dx = pv[which##_end].x - pv[which##_beg].x; \
-               which##_slope = (which##_dx << 8) / which##_dy; \
-       } while(0)
-
 void polyfill_flat(struct pvertex *pv, int nverts)
 {
-       int i, sline, x, slen, top = 0;
-       int left_beg, left_end, right_beg, right_end;
-       int32_t left_dy, left_dx, right_dy, right_dx;
-       int32_t left_slope, right_slope;
-       int32_t left_x, right_x, y;
-       uint16_t color = ((pv->r << 8) & 0xf800) | ((pv->g << 3) & 0x7e0) |
-               ((pv->b >> 3) & 0x1f);
-       uint16_t *pixptr;
-
-       /* find topmost */
+       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[top].y) {
-                       top = i;
-               }
+               if(pv[i].y < pv[topidx].y) topidx = i;
+               if(pv[i].y > pv[botidx].y) botidx = i;
        }
-       left_beg = right_beg = top;
-       left_end = PREVIDX(left_beg);
-       right_end = NEXTIDX(right_beg);
 
-       if((left_dy = pv[left_end].y - pv[left_beg].y)) {
-               CALC_EDGE(left);
+       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);
+               }
        }
 
-       if((right_dy = pv[right_end].y - pv[right_beg].y)) {
-               CALC_EDGE(right);
-       }
+       y = pv[topidx].y;
+       while(y < pv[botidx].y) {
+               int32_t x;
+               uint16_t *pixptr;
 
-       y = pv[top].y;
-       sline = pv[top].y >> 8;
+               sline = y >> 8;
+               x = left[sline].x;
 
-       for(;;) {
-               if(y >= pv[left_end].y) {
-                       while(y >= pv[left_end].y) {
-                               left_beg = left_end;
-                               if(left_beg == right_beg) return;
-                               left_end = PREVIDX(left_end);
-                       }
+               pixptr = pimg_fb.pixels + sline * pimg_fb.width + (x >> 8);
 
-                       left_dy = pv[left_end].y - pv[left_beg].y;
-                       CALC_EDGE(left);
+               while(x <= right[sline].x) {
+                       *pixptr++ += 15;
+                       x += 256;
                }
+               y += 256;
+       }
+}
 
-               if(y >= pv[right_end].y) {
-                       while(y >= pv[right_end].y) {
-                               right_beg = right_end;
-                               if(left_beg == right_beg) return;
-                               right_end = NEXTIDX(right_end);
-                       }
-
-                       right_dy = pv[right_end].y - pv[right_beg].y;
-                       CALC_EDGE(right);
-               }
+static void scan_edge(struct pvertex *v0, struct pvertex *v1, struct pvertex *edge)
+{
+       int32_t x, y, dx, dy, slope;
+       int idx;
 
-               x = left_x >> 8;
-               slen = (right_x >> 8) - (left_x >> 8);
+       if(v0->y > v1->y) {
+               struct pvertex *tmp = v0;
+               v0 = v1;
+               v1 = tmp;
+       }
 
-               pixptr = pimg_fb.pixels + sline * pimg_fb.width + x;
-               for(i=0; i<slen; i++) {
-                       *pixptr++ += 15;
-               }
+       dy = v1->y - v0->y;
+       dx = v1->x - v0->x;
+       slope = (dx << 8) / dy;
+       idx = v0->y >> 8;
 
-               ++sline;
+       x = v0->x;
+       y = v0->y;
+       while(y <= v1->y) {
+               edge[idx++].x = x;
+               x += slope;
                y += 256;
-               left_x += left_slope;
-               right_x += right_slope;
        }
 }

diff --git a/src/polytest.c b/src/polytest.c
index b9ad891..b81e9aa 100644 (file)
--- a/src/polytest.c
+++ b/src/polytest.c
@@ -35,7 +35,7 @@ static struct screen scr = {
 static float theta, phi = 25;
 static struct mesh cube, torus;
 
-#define LOWRES_SCALE   16
+#define LOWRES_SCALE   10
 static uint16_t *lowres_pixels;
 static int lowres_width, lowres_height;