From: John Tsiombikas <nuclear@mutantstargoat.com>
Date: Fri, 9 Sep 2016 04:19:21 +0000 (+0300)
Subject: torus with crude zsorting
X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?p=dosdemo;a=commitdiff_plain;h=90a1ba8903eed9e3d4b17f4b56cd02ed801dd8b6

torus with crude zsorting
---

diff --git a/src/3dgfx.c b/src/3dgfx.c
index 49b4c2c..31e649d 100644
--- a/src/3dgfx.c
+++ b/src/3dgfx.c
@@ -251,16 +251,25 @@ void g3d_perspective(float vfov_deg, float aspect, float znear, float zfar)
 	g3d_mult_matrix(m);
 }
 
-#define CROSS(res, a, b) \
-	do { \
-		(res)[0] = (a)[1] * (b)[2] - (a)[2] * (b)[1]; \
-		(res)[1] = (a)[2] * (b)[0] - (a)[0] * (b)[2]; \
-		(res)[2] = (a)[0] * (b)[1] - (a)[1] * (b)[0]; \
-	} while(0)
+const float *g3d_get_matrix(int which, float *m)
+{
+	int top = st->mtop[which];
+
+	if(m) {
+		memcpy(m, st->mat[which][top], 16 * sizeof(float));
+	}
+	return st->mat[which][top];
+}
 
 void g3d_draw(int prim, const struct g3d_vertex *varr, int varr_size)
 {
-	int i;
+	g3d_draw_indexed(prim, varr, varr_size, 0, 0);
+}
+
+void g3d_draw_indexed(int prim, const struct g3d_vertex *varr, int varr_size,
+		const int16_t *iarr, int iarr_size)
+{
+	int i, j, nfaces;
 	struct pvertex pv[4];
 	struct g3d_vertex v[4];
 	int vnum = prim; /* primitive vertex counts correspond to enum values */
@@ -271,11 +280,12 @@ void g3d_draw(int prim, const struct g3d_vertex *varr, int varr_size)
 	memcpy(st->norm_mat, st->mat[G3D_MODELVIEW][mvtop], 16 * sizeof(float));
 	st->norm_mat[12] = st->norm_mat[13] = st->norm_mat[14] = 0.0f;
 
-	while(varr_size >= vnum) {
-		varr_size -= vnum;
+	nfaces = (iarr ? iarr_size : varr_size) / vnum;
+
+	for(j=0; j<nfaces; j++) {
 
 		for(i=0; i<vnum; i++) {
-			v[i] = *varr++;
+			v[i] = iarr ? varr[*iarr++] : *varr++;
 
 			xform4_vec3(st->mat[G3D_MODELVIEW][mvtop], &v[i].x);
 			xform3_vec3(st->norm_mat, &v[i].nx);
diff --git a/src/3dgfx.h b/src/3dgfx.h
index 9e4b140..68d0783 100644
--- a/src/3dgfx.h
+++ b/src/3dgfx.h
@@ -63,6 +63,10 @@ void g3d_ortho(float left, float right, float bottom, float top, float znear, fl
 void g3d_frustum(float left, float right, float bottom, float top, float znear, float zfar);
 void g3d_perspective(float vfov, float aspect, float znear, float zfar);
 
+const float *g3d_get_matrix(int which, float *m);
+
 void g3d_draw(int prim, const struct g3d_vertex *varr, int varr_size);
+void g3d_draw_indexed(int prim, const struct g3d_vertex *varr, int varr_size,
+		const int16_t *iarr, int iarr_size);
 
 #endif	/* THREEDGFX_H_ */
diff --git a/src/demo.c b/src/demo.c
index fbcc4be..64bb965 100644
--- a/src/demo.c
+++ b/src/demo.c
@@ -23,6 +23,7 @@ int demo_init(int argc, char **argv)
 {
 	struct screen *scr;
 
+	start_scr_name = getenv("START_SCR");
 	if(argv[1]) {
 		start_scr_name = argv[1];
 	}
diff --git a/src/polytest.c b/src/polytest.c
index 5b43eea..a2985dd 100644
--- a/src/polytest.c
+++ b/src/polytest.c
@@ -1,6 +1,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <math.h>
 #include "screen.h"
 #include "demo.h"
 #include "3dgfx.h"
@@ -8,7 +9,7 @@
 struct mesh {
 	int prim;
 	struct g3d_vertex *varr;
-	unsigned int *iarr;
+	int16_t *iarr;
 	int vcount, icount;
 };
 
@@ -18,6 +19,9 @@ static void start(long trans_time);
 static void draw(void);
 static void draw_mesh(struct mesh *mesh);
 static int gen_cube(struct mesh *mesh, float sz);
+static int gen_torus(struct mesh *mesh, float rad, float ringrad, int usub, int vsub);
+static int dump_obj(const char *fname, struct mesh *m);
+static void zsort(struct mesh *m);
 
 static struct screen scr = {
 	"polytest",
@@ -27,7 +31,7 @@ static struct screen scr = {
 	draw
 };
 
-static struct mesh cube;
+static struct mesh cube, torus;
 
 struct screen *polytest_screen(void)
 {
@@ -37,6 +41,8 @@ struct screen *polytest_screen(void)
 static int init(void)
 {
 	gen_cube(&cube, 1.0);
+	gen_torus(&torus, 1.0, 0.25, 24, 12);
+	dump_obj("torus.obj", &torus);
 	return 0;
 }
 
@@ -82,13 +88,14 @@ static void draw(void)
 	g3d_rotate(phi, 1, 0, 0);
 	g3d_rotate(theta, 0, 1, 0);
 
-	draw_mesh(&cube);
+	zsort(&torus);
+	draw_mesh(&torus);
 }
 
 static void draw_mesh(struct mesh *mesh)
 {
 	if(mesh->iarr) {
-		/*g3d_draw_indexed(mesh->prim, mesh->iarr, mesh->icount, mesh->varr);*/
+		g3d_draw_indexed(mesh->prim, mesh->varr, mesh->vcount, mesh->iarr, mesh->icount);
 	} else {
 		g3d_draw(mesh->prim, mesh->varr, mesh->vcount);
 	}
@@ -163,3 +170,163 @@ static int gen_cube(struct mesh *mesh, float sz)
 
 	return 0;
 }
+
+static void torusvec(float *res, float theta, float phi, float mr, float rr)
+{
+	float rx, ry, rz;
+	theta = -theta;
+
+	rx = -cos(phi) * rr + mr;
+	ry = sin(phi) * rr;
+	rz = 0.0f;
+
+	res[0] = rx * sin(theta) + rz * cos(theta);
+	res[1] = ry;
+	res[2] = -rx * cos(theta) + rz * sin(theta);
+}
+
+static int gen_torus(struct mesh *mesh, float rad, float ringrad, int usub, int vsub)
+{
+	int i, j;
+	int nfaces, uverts, vverts;
+	struct g3d_vertex *vptr;
+	int16_t *iptr;
+
+	mesh->prim = G3D_QUADS;
+
+	if(usub < 4) usub = 4;
+	if(vsub < 2) vsub = 2;
+
+	uverts = usub + 1;
+	vverts = vsub + 1;
+
+	mesh->vcount = uverts * vverts;
+	nfaces = usub * vsub;
+	mesh->icount = nfaces * 4;
+
+	if(!(mesh->varr = malloc(mesh->vcount * sizeof *mesh->varr))) {
+		return -1;
+	}
+	if(!(mesh->iarr = malloc(mesh->icount * sizeof *mesh->iarr))) {
+		return -1;
+	}
+	vptr = mesh->varr;
+	iptr = mesh->iarr;
+
+	for(i=0; i<uverts; i++) {
+		float u = (float)i / (float)(uverts - 1);
+		float theta = u * 2.0 * M_PI;
+		float rcent[3];
+
+		torusvec(rcent, theta, 0, rad, 0);
+
+		for(j=0; j<vverts; j++) {
+			float v = (float)j / (float)(vverts - 1);
+			float phi = v * 2.0 * M_PI;
+			int chess = (i & 1) == (j & 1);
+
+			torusvec(&vptr->x, theta, phi, rad, ringrad);
+
+			vptr->nx = (vptr->x - rcent[0]) / ringrad;
+			vptr->ny = (vptr->y - rcent[1]) / ringrad;
+			vptr->nz = (vptr->z - rcent[2]) / ringrad;
+			vptr->u = u;
+			vptr->v = v;
+			vptr->r = chess ? 255 : 64;
+			vptr->g = 128;
+			vptr->b = chess ? 64 : 255;
+			++vptr;
+
+			if(i < usub && j < vsub) {
+				int idx = i * vverts + j;
+				*iptr++ = idx;
+				*iptr++ = idx + 1;
+				*iptr++ = idx + vverts + 1;
+				*iptr++ = idx + vverts;
+			}
+		}
+	}
+	return 0;
+}
+
+static int dump_obj(const char *fname, struct mesh *m)
+{
+	int i, j, nfaces;
+	FILE *fp;
+	struct g3d_vertex *vptr;
+	int16_t *iptr;
+
+	if(!(fp = fopen(fname, "wb"))) {
+		return -1;
+	}
+
+	nfaces = m->icount / m->prim;
+	printf("dumping obj: %s - %d vertices / %d faces (%d indices)\n", fname,
+			m->vcount, nfaces, m->icount);
+
+	vptr = m->varr;
+	for(i=0; i<m->vcount; i++) {
+		fprintf(fp, "v %f %f %f\n", vptr->x, vptr->y, vptr->z);
+		++vptr;
+	}
+	vptr = m->varr;
+	for(i=0; i<m->vcount; i++) {
+		fprintf(fp, "vn %f %f %f\n", vptr->nx, vptr->ny, vptr->nz);
+		++vptr;
+	}
+	vptr = m->varr;
+	for(i=0; i<m->vcount; i++) {
+		fprintf(fp, "vt %f %f\n", vptr->u, vptr->v);
+		++vptr;
+	}
+
+	iptr = m->iarr;
+	for(i=0; i<m->icount; i += m->prim) {
+		fputc('f', fp);
+		for(j=0; j<m->prim; j++) {
+			int idx = *iptr++ + 1;
+			fprintf(fp, " %d/%d/%d", idx, idx, idx);
+		}
+		fputc('\n', fp);
+	}
+
+	fclose(fp);
+	return 0;
+}
+
+static struct {
+	struct g3d_vertex *varr;
+	const float *xform;
+} zsort_cls;
+
+static int zsort_cmp(const void *aptr, const void *bptr)
+{
+	const int16_t *a = (const int16_t*)aptr;
+	const int16_t *b = (const int16_t*)bptr;
+
+	const float *m = zsort_cls.xform;
+
+	const struct g3d_vertex *va = zsort_cls.varr + a[0];
+	const struct g3d_vertex *vb = zsort_cls.varr + b[0];
+
+	float za = m[2] * va->x + m[6] * va->y + m[10] * va->z + m[14];
+	float zb = m[2] * vb->x + m[6] * vb->y + m[10] * vb->z + m[14];
+
+	va = zsort_cls.varr + a[2];
+	vb = zsort_cls.varr + b[2];
+
+	za += m[2] * va->x + m[6] * va->y + m[10] * va->z + m[14];
+	zb += m[2] * vb->x + m[6] * vb->y + m[10] * vb->z + m[14];
+
+	return za - zb;
+}
+
+static void zsort(struct mesh *m)
+{
+	int nfaces = m->icount / m->prim;
+
+	zsort_cls.varr = m->varr;
+	zsort_cls.xform = g3d_get_matrix(G3D_MODELVIEW, 0);
+
+	qsort(m->iarr, nfaces, m->prim * sizeof *m->iarr, zsort_cmp);
+}