shithub: libgraphics

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render: use the primitive's bbox to check for tile membership.

this fixes a bug i introduced with the fully concurrent pipeline,
where instead of testing whether the triangle *crossed* any of the
tiles, i checked whether any of the points *were inside*.

--- a/render.c

+++ b/render.c

@@ -311,11 +311,11 @@

 	t₂.p0 = Pt2(prim.v[0].p.x, prim.v[0].p.y, 1);

 	t₂.p1 = Pt2(prim.v[1].p.x, prim.v[1].p.y, 1);

 	t₂.p2 = Pt2(prim.v[2].p.x, prim.v[2].p.y, 1);

-	/* find the triangle's bbox and clip it against the fb */

-	bbox = Rect(

-		min(min(t₂.p0.x, t₂.p1.x), t₂.p2.x), min(min(t₂.p0.y, t₂.p1.y), t₂.p2.y),

-		max(max(t₂.p0.x, t₂.p1.x), t₂.p2.x)+1, max(max(t₂.p0.y, t₂.p1.y), t₂.p2.y)+1

-	);

+	/* find the triangle's bbox and clip it against our wr */

+	bbox.min.x = min(min(t₂.p0.x, t₂.p1.x), t₂.p2.x);

+	bbox.min.y = min(min(t₂.p0.y, t₂.p1.y), t₂.p2.y);

+	bbox.max.x = max(max(t₂.p0.x, t₂.p1.x), t₂.p2.x)+1;

+	bbox.max.y = max(max(t₂.p0.y, t₂.p1.y), t₂.p2.y)+1;

 	bbox.min.x = max(bbox.min.x, task->wr.min.x);

 	bbox.min.y = max(bbox.min.y, task->wr.min.y);

 	bbox.max.x = min(bbox.max.x, task->wr.max.x);

@@ -410,7 +410,7 @@

 	OBJElem **ep;

 	Point3 n;				/* surface normal */

 	Primitive *p;				/* primitives to raster */

-	Rectangle *wr;

+	Rectangle *wr, bbox;

 	Channel **taskc;

 	ulong Δy, nproc;

 	int i, np;

@@ -540,10 +540,13 @@

 				p[np].v[1].p = ndc2viewport(params->fb, p[np].v[1].p);

 				p[np].v[2].p = ndc2viewport(params->fb, p[np].v[2].p);

+				bbox.min.x = min(min(p[np].v[0].p.x, p[np].v[1].p.x), p[np].v[2].p.x);

+				bbox.min.y = min(min(p[np].v[0].p.y, p[np].v[1].p.y), p[np].v[2].p.y);

+				bbox.max.x = max(max(p[np].v[0].p.x, p[np].v[1].p.x), p[np].v[2].p.x)+1;

+				bbox.max.y = max(max(p[np].v[0].p.y, p[np].v[1].p.y), p[np].v[2].p.y)+1;

+

 				for(i = 0; i < nproc; i++)

-					if(ptinrect(Pt(p[np].v[0].p.x,p[np].v[0].p.y),wr[i]) ||

-					   ptinrect(Pt(p[np].v[1].p.x,p[np].v[1].p.y),wr[i]) ||

-					   ptinrect(Pt(p[np].v[2].p.x,p[np].v[2].p.y),wr[i])){

+					if(rectXrect(bbox,wr[i])){

 						newparams = emalloc(sizeof *newparams);

 						*newparams = *params;

 						task = emalloc(sizeof *task);