X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?p=dosdemo;a=blobdiff_plain;f=src%2Fpolytmpl.h;h=d61ac8eb21bd94546eba7fae1f320b7d72ee4219;hp=db5997a2774f64180bb74c8966dedd533fb467bf;hb=5029eb9f7a538dd58e1c66c0945784acac8cc58b;hpb=1bd8af3c3c9ec41903590d6ad24ff6313a5cc19b

diff --git a/src/polytmpl.h b/src/polytmpl.h
index db5997a..d61ac8e 100644
--- a/src/polytmpl.h
+++ b/src/polytmpl.h
@@ -93,8 +93,15 @@ void POLYFILL(struct pvertex *pv, int nverts)
 		if(pv[i].y > pv[botidx].y) botidx = i;
 	}
 
-	left = alloca(pfill_fb.height * sizeof *left);
-	right = alloca(pfill_fb.height * sizeof *right);
+	int winding = 0;
+	for(i=0; i<nverts; i++) {
+		int next = NEXTIDX(i);
+		winding += (pv[next].x - pv[i].x) * (pv[next].y + pv[i].y);
+	}
+
+	/* +1 to avoid crashing due to off-by-one rounding errors in the rasterization */
+	left = alloca((pfill_fb.height + 1) * sizeof *left);
+	right = alloca((pfill_fb.height + 1) * sizeof *right);
 
 	for(i=0; i<nverts; i++) {
 		int next = NEXTIDX(i);
@@ -132,9 +139,16 @@ void POLYFILL(struct pvertex *pv, int nverts)
 				if(idx < sltop) sltop = idx;
 			/*}*/
 		} else {
-			struct pvertex *edge = y0 > y1 ? left : right;
-			uint32_t res = SCANEDGE(pv + i, pv + next, edge);
-			uint32_t tmp = (res >> 16) & 0xffff;
+			struct pvertex *edge;
+			uint32_t res, tmp;
+
+			if(winding < 0) {
+				edge = y0 > y1 ? left : right;
+			} else {
+				edge = y0 > y1 ? right : left;
+			}
+			res = SCANEDGE(pv + i, pv + next, edge);
+			tmp = (res >> 16) & 0xffff;
 			if(tmp > slbot) slbot = tmp;
 			if((tmp = res & 0xffff) < sltop) {
 				sltop = tmp;