shithub: libgraphics

Info  •  Files  •  Log  •  Branches

render: handle special case of triangle surrounds tile in mktribbox()

if the triangle happens to not clip the tile at all,
we end up with an OOB rect. instead return the tile
rect itself (wr), as expected.

--- a/render.c

+++ b/render.c

@@ -376,9 +376,8 @@

 static Rectangle

 mktribbox(Point3 p0, Point3 p1, Point3 p2, Rectangle wr)

 {

-	Point l[6];

+	Point l[6], *e0, *e1;

 	Rectangle r;

-	int i;

 	l[0] = (Point){p0.x+0.5, p0.y+0.5};

 	l[1] = (Point){p1.x+0.5, p1.y+0.5};

@@ -389,13 +388,16 @@

 	r.min = (Point){ 100000, 100000};

 	r.max = (Point){-100000,-100000};

-	for(i = 0; i < 6; i += 2)

-		if(_rectclipline(wr, l+i, l+i+1)){

-			r.min.x = min(r.min.x, l[i].x); r.min.x = min(r.min.x, l[i+1].x);

-			r.min.y = min(r.min.y, l[i].y); r.min.y = min(r.min.y, l[i+1].y);

-			r.max.x = max(r.max.x, l[i].x); r.max.x = max(r.max.x, l[i+1].x);

-			r.max.y = max(r.max.y, l[i].y); r.max.y = max(r.max.y, l[i+1].y);

+	for(e0 = &l[0], e1 = &l[1]; e1 < l + nelem(l); e0 += 2, e1 += 2)

+		if(_rectclipline(wr, e0, e1)){

+			r.min.x = min(r.min.x, e0->x); r.min.x = min(r.min.x, e1->x);

+			r.min.y = min(r.min.y, e0->y); r.min.y = min(r.min.y, e1->y);

+			r.max.x = max(r.max.x, e0->x); r.max.x = max(r.max.x, e1->x);

+			r.max.y = max(r.max.y, e0->y); r.max.y = max(r.max.y, e1->y);

 		}

+	/* exception when triangle surrounds the tile */

+	if(r.min.x > r.max.x || r.min.y > r.max.y)

+		return wr;

 	r.max.x++;

 	r.max.y++;

 	/* simplified rectclip(2) */

@@ -460,13 +462,13 @@

 		z = ∇.z.f0;

 		pcz = ∇.pcz.f0;

 	for(p.x = task->wr.min.x; p.x < task->wr.max.x; p.x++){

-//		if(p.x == task->wr.min.x || p.x == task->wr.max.x-1

-//		|| p.y == task->wr.min.y || p.y == task->wr.max.y-1){

-//			pixel(cr, p, (Color){1,0,0,1}, 0);

-//			putdepth(zr, p, 1);

-//			task->clipr->min = minpt(task->clipr->min, p);

-//			task->clipr->max = maxpt(task->clipr->max, p);

-//		}

+		if(p.x == task->wr.min.x || p.x == task->wr.max.x-1

+		|| p.y == task->wr.min.y || p.y == task->wr.max.y-1){

+			pixel(cr, p, (Color){1,0,0,1}, 0);

+			putdepth(zr, p, 1);

+			task->clipr->min = minpt(task->clipr->min, p);

+			task->clipr->max = maxpt(task->clipr->max, p);

+		}

 		if(bc.x < 0 || bc.y < 0 || bc.z < 0)

 			goto discard;

-- 

⑨