From: John Tsiombikas <nuclear@member.fsf.org>
Date: Sat, 3 Feb 2018 22:44:45 +0000 (+0200)
Subject: clipping bugs...
X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?p=dosdemo;a=commitdiff_plain;h=1723e332319e7732473814dfc168a13d0bafccb4

clipping bugs...
---

diff --git a/src/3dgfx.c b/src/3dgfx.c
index 46cc9ab..a90da7a 100644
--- a/src/3dgfx.c
+++ b/src/3dgfx.c
@@ -98,9 +98,7 @@ void g3d_framebuffer(int width, int height, void *pixels)
 	pfill_fb.width = width;
 	pfill_fb.height = height;
 
-	st->vport[0] = st->vport[1] = 0;
-	st->vport[2] = width;
-	st->vport[3] = height;
+	g3d_viewport(0, 0, width, height);
 }
 
 void g3d_viewport(int x, int y, int w, int h)
@@ -404,6 +402,7 @@ void g3d_draw_indexed(int prim, const struct g3d_vertex *varr, int varr_size,
 	nfaces = (iarr ? iarr_size : varr_size) / vnum;
 
 	for(j=0; j<nfaces; j++) {
+		vnum = prim;	/* reset vnum for each iteration */
 
 		for(i=0; i<vnum; i++) {
 			v[i] = iarr ? varr[*iarr++] : *varr++;
@@ -419,15 +418,18 @@ void g3d_draw_indexed(int prim, const struct g3d_vertex *varr, int varr_size,
 
 		/* clipping */
 		for(i=0; i<6; i++) {
-			struct g3d_vertex orig[16];
-			memcpy(orig, v, vnum * sizeof *v);
+			struct g3d_vertex tmpv[16];
+			memcpy(tmpv, v, vnum * sizeof *v);
 
-			if(clip_frustum(v, &vnum, orig, vnum, i) < 0) {
+			if(clip_frustum(v, &vnum, tmpv, vnum, i) < 0) {
 				/* polygon completely outside of view volume. discard */
-				return;
+				vnum = 0;
+				break;
 			}
 		}
 
+		if(!vnum) continue;
+
 		for(i=0; i<vnum; i++) {
 			if(v[i].w != 0.0f) {
 				v[i].x /= v[i].w;
diff --git a/src/metaball.c b/src/metaball.c
index af7ea93..f9bc61c 100644
--- a/src/metaball.c
+++ b/src/metaball.c
@@ -134,7 +134,7 @@ static void update(void)
 
 	{
 		int i, j;
-		float tsec = 0;//time_msec / 1000.0f;
+		float tsec = time_msec / 1000.0f;
 		static float phase[] = {0.0, M_PI / 3.0, M_PI * 0.8};
 		static float speed[] = {0.8, 1.4, 1.0};
 		static float scale[][3] = {{1, 2, 0.8}, {0.5, 1.6, 0.6}, {1.5, 0.7, 0.5}};
@@ -186,6 +186,8 @@ static void draw(void)
 
 	draw_mesh(&mmesh);
 
+	g3d_viewport(0, 0, fb_width, fb_height);
+
 	swap_buffers(fb_pixels);
 }
 
diff --git a/src/polytmpl.h b/src/polytmpl.h
index db5997a..12df420 100644
--- a/src/polytmpl.h
+++ b/src/polytmpl.h
@@ -93,8 +93,9 @@ 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);
+	/* +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);
diff --git a/src/sdl/main.c b/src/sdl/main.c
index 05744e8..09645aa 100644
--- a/src/sdl/main.c
+++ b/src/sdl/main.c
@@ -30,7 +30,8 @@ int main(int argc, char **argv)
 	xsz = fb_width * fbscale;
 	ysz = fb_height * fbscale;
 
-	if(!(fb_pixels = malloc(fb_width * fb_height * fb_bpp / CHAR_BIT))) {
+	/* allocate 1 extra row as a guard band, until we fucking fix the rasterizer */
+	if(!(fb_pixels = malloc(fb_width * (fb_height + 1) * fb_bpp / CHAR_BIT))) {
 		fprintf(stderr, "failed to allocate virtual framebuffer\n");
 		return 1;
 	}