shithub: libgraphics

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ref: 5e7ea1dfc93eea222c62c818cfab760802459cd1
parent: 93217b6b2c2e5eecc7fe0f412fe2a7d0aa4b4a3c
author: rodri <rgl@antares-labs.eu>
date: Tue Jun 24 13:29:48 EDT 2025 

add backend Vertex and Primitive types for internal use

this draws a clear distinction between the data processed by the renderer and the one manipulated by the user, decoupling the logic and serving as a first step towards the optimization of geometry storage. there are properties like per-vertex tangents, materials and Vertexattrs (varyings) that have no meaning outside of the rendering pipeline, so it makes no sense to keep space for them.


--- a/clip.c
+++ b/clip.c
@@ -29,7 +29,7 @@
 }
 
 static int
-addvert(Polygon *p, Vertex v)
+addvert(Polygon *p, BVertex v)
 {
 	if(++p->n > p->cap)
 		p->v = _erealloc(p->v, (p->cap = p->n)*sizeof(*p->v));
@@ -63,7 +63,7 @@
  * 	- https://github.com/aap/librw/blob/14dab85dcae6f3762fb2b1eda4d58d8e67541330/tools/playground/tl_tests.cpp#L522
  */
 int
-_clipprimitive(Primitive *p, Primitive *cp)
+_clipprimitive(BPrimitive *p, BPrimitive *cp)
 {
 	/* signed distance from each clipping plane */
 	static double sdm[6][4] = {
@@ -77,7 +77,7 @@
 	double sd0[6], sd1[6];
 	double d0, d1, perc;
 	Polygon Vinp, Voutp, *Vin, *Vout;
-	Vertex *v0, *v1, v;	/* edge verts and new vertex (line-plane intersection) */
+	BVertex *v0, *v1, v;	/* edge verts and new vertex (line-plane intersection) */
 	int i, j, np;
 
 	np = 0;
@@ -184,9 +184,9 @@
 
 /* lerp vertex attributes to match the new positions */
 static void
-adjustverts(Point *p0, Point *p1, Vertex *v0, Vertex *v1)
+adjustverts(Point *p0, Point *p1, BVertex *v0, BVertex *v1)
 {
-	Vertex v[2];
+	BVertex v[2];
 	Point3 dp;
 	Point Δp;
 	double len, perc;
@@ -214,7 +214,7 @@
  * Cohen-Sutherland rectangle-line clipping
  */
 int
-_rectclipline(Rectangle r, Point *p0, Point *p1, Vertex *v0, Vertex *v1)
+_rectclipline(Rectangle r, Point *p0, Point *p1, BVertex *v0, BVertex *v1)
 {
 	int code0, code1;
 	int Δx, Δy;
@@ -237,7 +237,7 @@
 		if(ptisinside(code0)){
 			SWAP(Point, p0, p1);
 			SWAP(int, &code0, &code1);
-			SWAP(Vertex, v0, v1);
+			SWAP(BVertex, v0, v1);
 		}
 
 		if(code0 & CLIPL){
--- a/graphics.h
+++ b/graphics.h
@@ -58,6 +58,7 @@
 typedef struct Vertexattr Vertexattr;
 typedef struct Vertexattrs Vertexattrs;
 typedef struct Vertex Vertex;
+typedef struct BVertex BVertex;
 typedef struct LightSource LightSource;
 typedef struct Material Material;
 typedef struct Primitive Primitive;
@@ -141,6 +142,16 @@
 	Point3 n;		/* surface normal */
 	Color c;		/* shading color */
 	Point2 uv;		/* texture coordinate */
+};
+
+/*
+ * BVertex is only used internally in the rasterizer, but it's
+ * presented to the user by the Shaderparams so its definition must be
+ * publicly available.
+ */
+struct BVertex
+{
+	Vertex;
 	Material *mtl;
 	Point3 tangent;
 	Vertexattrs;		/* attributes (varyings) */
@@ -219,7 +230,7 @@
 struct Shaderparams
 {
 	SUparams *su;
-	Vertex *v;
+	BVertex *v;
 	Point p;	/* fragment position (fshader-only) */
 	uint idx;	/* vertex index (vshader-only) */
 
--- a/internal.h
+++ b/internal.h
@@ -10,6 +10,7 @@
 	OP_END,
 };
 
+typedef struct BPrimitive BPrimitive;
 typedef struct Polygon Polygon;
 typedef struct Entityparam Entityparam;
 typedef struct Tilerparam Tilerparam;
@@ -19,9 +20,17 @@
 typedef struct pGradient pGradient;
 typedef struct vGradient vGradient;
 
+struct BPrimitive
+{
+	int type;
+	BVertex v[3];
+	Material *mtl;
+	Point3 tangent;		/* used for normal mapping */
+};
+
 struct Polygon
 {
-	Vertex *v;
+	BVertex *v;
 	ulong n;
 	ulong cap;
 };
@@ -53,7 +62,7 @@
 	Shaderparams *fsp;
 	Rectangle wr;		/* working rect */
 	Rectangle *clipr;
-	Primitive p;
+	BPrimitive p;
 };
 
 struct fGradient
@@ -72,9 +81,9 @@
 
 struct vGradient
 {
-	Vertex v0;
-	Vertex dx;
-	Vertex dy;
+	BVertex v0;
+	BVertex dx;
+	BVertex dy;
 };
 
 /* alloc */
@@ -102,20 +111,20 @@
 void _rmfbctl(Framebufctl*);
 
 /* vertex */
-Vertex _dupvertex(Vertex*);
-void _loadvertex(Vertex*, Vertex*);
-void _lerpvertex(Vertex*, Vertex*, Vertex*, double);
-void _berpvertex(Vertex*, Vertex*, Vertex*, Vertex*, Point3);
-void _addvertex(Vertex*, Vertex*);
-void _mulvertex(Vertex*, double);
-void _delvattrs(Vertex*);
-void _fprintvattrs(int, Vertex*);
+BVertex _dupvertex(BVertex*);
+void _loadvertex(BVertex*, BVertex*);
+void _lerpvertex(BVertex*, BVertex*, BVertex*, double);
+void _berpvertex(BVertex*, BVertex*, BVertex*, BVertex*, Point3);
+void _addvertex(BVertex*, BVertex*);
+void _mulvertex(BVertex*, double);
+void _delvattrs(BVertex*);
+void _fprintvattrs(int, BVertex*);
 void _addvattr(Vertexattrs*, char*, int, void*);
 Vertexattr *_getvattr(Vertexattrs*, char*);
 
 /* clip */
-int _clipprimitive(Primitive*, Primitive*);
-int _rectclipline(Rectangle, Point*, Point*, Vertex*, Vertex*);
+int _clipprimitive(BPrimitive*, BPrimitive*);
+int _rectclipline(Rectangle, Point*, Point*, BVertex*, BVertex*);
 
 /* util */
 void _memsetl(void*, ulong, usize);
--- a/render.c
+++ b/render.c
@@ -84,7 +84,7 @@
 }
 
 static int
-isfacingback(Primitive *p)
+isfacingback(BPrimitive *p)
 {
 	double sa;	/* signed double area */
 
@@ -176,7 +176,7 @@
 {
 	SUparams *params;
 	Raster *cr, *zr;
-	Primitive *prim;
+	BPrimitive *prim;
 	Point p;
 	Color c;
 	float z;
@@ -222,7 +222,7 @@
 {
 	SUparams *params;
 	Raster *cr, *zr;
-	Primitive *prim;
+	BPrimitive *prim;
 	Point p, dp, Δp, p0, p1;
 	Color c;
 	double dplen, perc;
@@ -255,7 +255,7 @@
 	/* make them left-to-right */
 	if(p0.x > p1.x){
 		SWAP(Point, &p0, &p1);
-		SWAP(Vertex, prim->v+0, prim->v+1);
+		SWAP(BVertex, prim->v+0, prim->v+1);
 	}
 
 	dp = subpt(p1, p0);
@@ -334,11 +334,11 @@
 {
 	SUparams *params;
 	Raster *cr, *zr;
-	Primitive *prim;
+	BPrimitive *prim;
 	pGradient ∇bc;
 //	vGradient ∇v;
 //	fGradient ∇z, ∇pcz;
-//	Vertex v, *vp;
+//	BVertex v, *vp;
 	Triangle2 t;
 	Point p;
 	Point3 bc;
@@ -423,10 +423,10 @@
 //		_loadvertex(vp, task->fsp->v);
 //		_mulvertex(vp, 1/(pcz < ε1? ε1: pcz));
 
-//		SWAP(Vertex*, &vp, &task->fsp->v);
+//		SWAP(BVertex*, &vp, &task->fsp->v);
 		task->fsp->p = p;
 		c = params->stab->fs(task->fsp);
-//		SWAP(Vertex*, &vp, &task->fsp->v);
+//		SWAP(BVertex*, &vp, &task->fsp->v);
 		if(c.a == 0)			/* discard non-colors */
 			goto discard;
 		if(ropts & RODepth)
@@ -472,7 +472,7 @@
 	Rastertask *task;
 	SUparams *params;
 	Renderjob *job;
-	Vertex v;
+	BVertex v;
 	Shaderparams fsp;
 	int i;
 
@@ -556,7 +556,8 @@
 	SUparams *params, *newparams;
 	Rastertask *task;
 	Shaderparams vsp;
-	Primitive *ep, *cp, *p, prim;	/* primitives to raster */
+	Primitive *ep;			/* primitives to raster */
+	BPrimitive prim, *p, *cp;
 	Rectangle *wr, bbox;
 	Channel **taskchans;
 	ulong nproc;
@@ -565,7 +566,7 @@
 	tp = arg;
 	threadsetname("tiler %d", tp->id);
 
-	cp = _emalloc(sizeof(*cp)*16);
+	cp = _emalloc(16*sizeof(*cp));
 	taskchans = tp->taskchans;
 	nproc = tp->nproc;
 	wr = _emalloc(nproc*sizeof(Rectangle));
@@ -607,7 +608,11 @@
 		for(ep = params->eb; ep != params->ee; ep++){
 			np = 1;	/* start with one. after clipping it might change */
 
-			prim = *ep;
+			prim.type = ep->type;
+			for(i = 0; i < prim.type+1; i++)
+				prim.v[i].Vertex = ep->v[i];
+			prim.mtl = ep->mtl;
+			prim.tangent = ep->tangent;
 			p = &prim;
 			switch(p->type){
 			case PPoint:
--- a/vertex.c
+++ b/vertex.c
@@ -25,7 +25,7 @@
 }
 
 static void
-copyvattrs(Vertex *d, Vertex *s)
+copyvattrs(BVertex *d, BVertex *s)
 {
 	int i;
 
@@ -33,10 +33,10 @@
 		addvattr(d, &s->attrs[i]);
 }
 
-Vertex
-_dupvertex(Vertex *v)
+BVertex
+_dupvertex(BVertex *v)
 {
-	Vertex nv;
+	BVertex nv;
 
 	nv = *v;
 	nv.attrs = nil;
@@ -46,7 +46,7 @@
 }
 
 void
-_loadvertex(Vertex *d, Vertex *s)
+_loadvertex(BVertex *d, BVertex *s)
 {
 	d->p = s->p;
 	d->n = s->n;
@@ -61,7 +61,7 @@
  * linear attribute interpolation
  */
 void
-_lerpvertex(Vertex *v, Vertex *v0, Vertex *v1, double t)
+_lerpvertex(BVertex *v, BVertex *v0, BVertex *v1, double t)
 {
 	Vertexattr va;
 	int i;
@@ -87,7 +87,7 @@
  * barycentric attribute interpolation
  */
 void
-_berpvertex(Vertex *v, Vertex *v0, Vertex *v1, Vertex *v2, Point3 bc)
+_berpvertex(BVertex *v, BVertex *v0, BVertex *v1, BVertex *v2, Point3 bc)
 {
 	Vertexattr va;
 	int i;
@@ -110,7 +110,7 @@
 }
 
 void
-_addvertex(Vertex *a, Vertex *b)
+_addvertex(BVertex *a, BVertex *b)
 {
 	Vertexattr *va, *vb;
 
@@ -128,7 +128,7 @@
 }
 
 void
-_mulvertex(Vertex *v, double s)
+_mulvertex(BVertex *v, double s)
 {
 	Vertexattr *va;
 
@@ -171,7 +171,7 @@
 }
 
 void
-_delvattrs(Vertex *v)
+_delvattrs(BVertex *v)
 {
 	free(v->attrs);
 	v->attrs= nil;
@@ -179,7 +179,7 @@
 }
 
 void
-_fprintvattrs(int fd, Vertex *v)
+_fprintvattrs(int fd, BVertex *v)
 {
 	int i;
 
-- 
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