shithub: libgraphics

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remove redundant z gradients from incremental rasterizer

--- a/internal.h

+++ b/internal.h

@@ -12,7 +12,6 @@

 typedef struct Tilertask	Tilertask;

 typedef struct Rasterparam	Rasterparam;

 typedef struct Rastertask	Rastertask;

-typedef struct fGradient	fGradient;

 typedef struct pGradient	pGradient;

 typedef struct vGradient	vGradient;

 typedef struct Gradients	Gradients;

@@ -80,13 +79,6 @@

 	BPrimitive	p;

 };

-struct fGradient

-{

-	double	f0;

-	double	dx;

-	double	dy;

-};

-

 struct pGradient

 {

 	Point3	p0;

@@ -105,8 +97,6 @@

 {

 	vGradient	v;

 	pGradient	bc;

-	fGradient	z;

-	fGradient	pcz;

 };

 /* alloc */

--- a/render.c

+++ b/render.c

@@ -363,14 +363,6 @@

 	_berpvertex(&∇->v.v0, prim->v+0, prim->v+1, prim->v+2, ∇->bc.p0);

 	_berpvertex(&∇->v.dx, prim->v+0, prim->v+1, prim->v+2, ∇->bc.dx);

 	_berpvertex(&∇->v.dy, prim->v+0, prim->v+1, prim->v+2, ∇->bc.dy);

-

-	∇->z.f0 = fberp(prim->v[0].p.z, prim->v[1].p.z, prim->v[2].p.z, ∇->bc.p0);

-	∇->z.dx = fberp(prim->v[0].p.z, prim->v[1].p.z, prim->v[2].p.z, ∇->bc.dx);

-	∇->z.dy = fberp(prim->v[0].p.z, prim->v[1].p.z, prim->v[2].p.z, ∇->bc.dy);

-

-	∇->pcz.f0 = fberp(prim->v[0].p.w, prim->v[1].p.w, prim->v[2].p.w, ∇->bc.p0);

-	∇->pcz.dx = fberp(prim->v[0].p.w, prim->v[1].p.w, prim->v[2].p.w, ∇->bc.dx);

-	∇->pcz.dy = fberp(prim->v[0].p.w, prim->v[1].p.w, prim->v[2].p.w, ∇->bc.dy);

 }

 static Rectangle

@@ -419,7 +411,6 @@

 	Point p;

 	Point3 bc;

 	Color c;

-	float z, pcz;

 	uint ropts;

 	prim = &task->p;

@@ -459,8 +450,6 @@

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

 		bc = ∇.bc.p0;

 		*sp->v = ∇.v.v0;

-		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){

@@ -472,12 +461,12 @@

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

 			goto discard;

-		if((ropts & RODepth) && z <= getdepth(zr, p))

+		if((ropts & RODepth) && sp->v->p.z <= getdepth(zr, p))

 			goto discard;

 		/* perspective-correct attribute interpolation  */

 		v = *sp->v;

-		_mulvertex(sp->v, 1.0/(pcz < ε1? ε1: pcz));

+		_mulvertex(sp->v, 1.0/(sp->v->p.w < ε1? ε1: sp->v->p.w));

 		sp->p = p;

 		c = sp->stab->fs(sp);

@@ -485,9 +474,9 @@

 		if(c.a == 0)			/* discard non-colors */

 			goto discard;

 		if(ropts & RODepth)

-			putdepth(zr, p, z);

+			putdepth(zr, p, sp->v->p.z);

 		if(ropts & ROAbuff)

-			pushtoAbuf(sp->fb, p, c, z);

+			pushtoAbuf(sp->fb, p, c, sp->v->p.z);

 		else

 			pixel(cr, p, c, ropts & ROBlend);

@@ -496,13 +485,9 @@

 discard:

 		bc = addpt3(bc, ∇.bc.dx);

 		_addvertex(sp->v, &∇.v.dx);

-		z += ∇.z.dx;

-		pcz += ∇.pcz.dx;

 	}

 		∇.bc.p0 = addpt3(∇.bc.p0, ∇.bc.dy);

 		_addvertex(&∇.v.v0, &∇.v.dy);

-		∇.z.f0 += ∇.z.dy;

-		∇.pcz.f0 += ∇.pcz.dy;

 	}

 }

--- a/vertex.c

+++ b/vertex.c

@@ -90,6 +90,7 @@

 {

 	Vertexattr *va, *vb, *ve;

+	a->p = addpt3(a->p, b->p);

 	a->n = addpt3(a->n, b->n);

 	a->c = addpt3(a->c, b->c);

 	a->uv = addpt2(a->uv, b->uv);

@@ -103,6 +104,10 @@

 	}

 }

+/*

+ * this is only used for attribute linearization and subsequent

+ * perspective correction, so we can omit the position.

+ */

 void

 _mulvertex(BVertex *v, double s)

 {

-- 

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