shithub: libgraphics

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completed homogeneous clipping procedure.

--- a/graphics.h

+++ b/graphics.h

@@ -5,8 +5,18 @@

 	PERSPECTIVE

 } Projection;

+enum {

+	LIGHT_POINT,

+	LIGHT_DIRECTIONAL,

+};

+

 typedef struct Color Color;

 typedef struct Vertex Vertex;

+typedef struct LightSource LightSource;

+typedef struct Material Material;

+typedef struct Model Model;

+typedef struct Entity Entity;

+typedef struct Environment Environment;

 typedef struct VSparams VSparams;

 typedef struct FSparams FSparams;

 typedef struct SUparams SUparams;

@@ -27,9 +37,40 @@

 	Point3 n;	/* surface normal */

 	Color c;	/* shading color */

 	Point2 uv;	/* texture coordinate */

+

+	double intensity;

 };

 typedef Vertex Triangle[3];

+

+struct LightSource

+{

+	Point3 p;

+	int type;

+};

+

+struct Material

+{

+	int stub;

+};

+

+struct Model

+{

+	Material *materials;

+	ulong nmaterials;

+};

+

+struct Entity

+{

+	Model *mdl;

+};

+

+struct Scene

+{

+	Entity **ents;

+	ulong nents;

+	

+};

 /* shader params */

 struct VSparams

--- a/render.c

+++ b/render.c

@@ -30,7 +30,7 @@

 	OBJIndexArray *idxtab;

 	idxtab = &e->indextab[OBJVGeometric];

-	newe[0] = emalloc(sizeof *newe[0]);

+	newe[0] = emalloc(sizeof **newe);

 	newe[0]->type = OBJEFace;

 	newidxtab = &newe[0]->indextab[OBJVGeometric];

 	newidxtab->nindex = 3;

@@ -58,7 +58,7 @@

 	}

 	idxtab = &e->indextab[OBJVGeometric];

-	newe[1] = emalloc(sizeof *newe[1]);

+	newe[1] = emalloc(sizeof **newe);

 	newe[1]->type = OBJEFace;

 	newidxtab = &newe[1]->indextab[OBJVGeometric];

 	newidxtab->nindex = 3;

@@ -104,7 +104,7 @@

 	int i;

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

-		r[i] += m[i][0]*p.x + m[i][1]*p.y + m[i][2]*p.z + m[i][3]*p.w;

+		r[i] = m[i][0]*p.x + m[i][1]*p.y + m[i][2]*p.z + m[i][3]*p.w;

 }

 typedef struct

@@ -123,31 +123,38 @@

 	return p->n;

 }

+static void

+swappoly(Polygon *a, Polygon *b)

+{

+	Polygon tmp;

+

+	tmp = *a;

+	*a = *b;

+	*b = tmp;

+}

+

+/*

+ * references:

+ * 	- James F. Blinn, Martin E. Newell, “Clipping Using Homogeneous Coordinates”,

+ * 	  SIGGRAPH '78, pp. 245-251

+ * 	- https://cs418.cs.illinois.edu/website/text/clipping.html

+ * 	- https://github.com/aap/librw/blob/14dab85dcae6f3762fb2b1eda4d58d8e67541330/tools/playground/tl_tests.cpp#L522

+ */

 static int

 cliptriangle(Triangle *t)

 {

-	/* TODO implement homogeneous clipping procedure */

-	/*

-	 * requirements:

-	 *

-	 * - normal and color attributes are carried over to the new

-	 *   intersecting points without modification.

-	 * - uv coordinates must be adjusted in proportion to the new

-	 *   points.

-	 */

-	enum { L, R, B, T, F, N };

 	/* signed distance from each clipping plane */

 	static double sdm[6][4] = {

-		 1,  0,  0, 1,

-		-1,  0,  0, 1,

-		 0,  1,  0, 1,

-		 0, -1,  0, 1,

-		 0,  0,  1, 1,

-		 0,  0, -1, 1,

+		 1,  0,  0, 1,	/* l */

+		-1,  0,  0, 1,	/* r */

+		 0,  1,  0, 1,	/* b */

+		 0, -1,  0, 1,	/* t */

+		 0,  0,  1, 1,	/* f */

+		 0,  0, -1, 1,	/* n */

 	}, sd0[6], sd1[6];

-	double d0, d1;

-	Polygon Vout;

-	Vertex *v0, *v1, v;	/* new vertex (line-plane intersection) */

+	double d0, d1, perc;

+	Polygon Vin, Vout;

+	Vertex *v0, *v1, v;	/* edge verts and new vertex (line-plane intersection) */

 	int i, j, nt;

 	if(!isvisible(t[0][0].p) && !isvisible(t[0][1].p) && !isvisible(t[0][2].p))

@@ -154,23 +161,21 @@

 		return 0;

 	nt = 0;

+	memset(&Vin, 0, sizeof Vin);

 	memset(&Vout, 0, sizeof Vout);

+	for(i = 0; i < 3; i++)

+		addvert(&Vin, t[0][i]);

-	for(i = 0; i < 3; i++){

-		v0 = &t[0][i];

-		v1 = &t[0][(i+1) % 3];

-		memset(sd0, 0, sizeof sd0);

-		memset(sd1, 0, sizeof sd1);

-		mulsdm(sd0, sdm, v0->p);

-		mulsdm(sd1, sdm, v1->p);

+	for(j = 0; j < 6; j++){

+		for(i = 0; i < Vin.n; i++){

+			v0 = &Vin.v[i];

+			v1 = &Vin.v[(i+1) % Vin.n];

-		for(j = 0; j < 6; j++){

-			/*

-			 * if both verts are outside any of the planes, they

-			 * are not in the frustum, so no need to keep testing.

-			 */

+			mulsdm(sd0, sdm, v0->p);

+			mulsdm(sd1, sdm, v1->p);

+

 			if(sd0[j] < 0 && sd1[j] < 0)

-				break;

+				continue;

 			if(sd0[j] >= 0 && sd1[j] >= 0)

 				goto allin;

@@ -180,8 +185,10 @@

 			d0 = (j&1) == 0? sd0[j]: -sd0[j];

 			d1 = (j&1) == 0? sd1[j]: -sd1[j];

-			v.p = divpt3(subpt3(mulpt3(v0->p, d1), mulpt3(v1->p, d0)), d1-d0);

-			v.uv = divpt2(subpt2(mulpt2(v0->uv, d1), mulpt2(v1->uv, d0)), d1-d0);

+			perc = d0/(d0 - d1);

+			v.p = lerp3(v0->p, v1->p, perc);

+			v.uv = lerp2(v0->uv, v1->uv, perc);

+			v.intensity = flerp(v0->intensity, v1->intensity, perc);

 			addvert(&Vout, v);

 			if(sd1[j] >= 0){

@@ -189,8 +196,18 @@

 				addvert(&Vout, *v1);

 			}

 		}

+		if(j < 6-1){

+			swappoly(&Vin, &Vout);

+			Vout.n = 0;

+		}

 	}

+	if(Vout.n < 3){

+		free(Vout.v);

+		free(Vin.v);

+		return 0;

+	}

+

 	/* triangulate */

 	for(i = 0; i < Vout.n-2; i++, nt++){

 		t[nt][0] = Vout.v[0];

@@ -198,6 +215,7 @@

 		t[nt][2] = Vout.v[i+2];

 	}

 	free(Vout.v);

+	free(Vin.v);

 	return nt;

 }

@@ -390,6 +408,9 @@

 			}else

 				memset(cbuf, 0xFF, sizeof cbuf);

+			params->var_intensity[0] = t[0].intensity;

+			params->var_intensity[1] = t[1].intensity;

+			params->var_intensity[2] = t[2].intensity;

 			fsp.p = p;

 			fsp.bc = bc;

 			pixel(params->fb->cb, p, params->fshader(&fsp));

@@ -415,7 +436,7 @@

 	threadsetname("shader unit #%d", params->id);

-	t = emalloc(sizeof(*t)*32);

+	t = emalloc(sizeof(*t)*16);

 	verts = params->model->vertdata[OBJVGeometric].verts;

 	tverts = params->model->vertdata[OBJVTexture].verts;

 	nverts = params->model->vertdata[OBJVNormal].verts;