raytrace: initial code

utils/gr-sim/raytrace/Makefile

@@ -0,0 +1,18 @@
+CC = gcc
+CFLAGS = -O2 -Wall -I.. -g
+LFLAGS = -lm
+
+SDL_LIBS= `sdl-config --libs`
+SDL_INCLUDE= `sdl-config --cflags`
+GR_SIM = ../gr-sim.a
+
+all:	raytrace
+
+raytrace: raytrace.o
+	$(CC) -o raytrace raytrace.o $(GR_SIM) $(SDL_LIBS) $(LFLAGS)
+
+raytrace.o:	raytrace.c
+	$(CC) $(CFLAGS) -c raytrace.c
+
+clean:	
+	rm -f *~ *.o raytrace

utils/gr-sim/raytrace/raytrace.c

@@ -0,0 +1,164 @@
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <math.h>
+
+#include "gr-sim.h"
+#include "tfv_zp.h"
+
+#define XSIZE	40
+#define YSIZE	48
+
+static unsigned int frame=0;
+
+static float c_w=XSIZE,c_h=YSIZE;
+static float v_w=1.0,v_h=1.0,dd=1.0;
+
+struct vector {
+	float x,y,z;
+} d;
+
+static int canvas_to_viewport(int xx, int yy, struct vector *d) {
+
+	d->x=xx*v_w/c_w;
+	d->y=yy*v_h/c_h;
+	d->z=dd;
+
+	return 0;
+}
+
+#define NUM_SPHERES	3
+
+struct sphere_type {
+	struct vector center;
+	float radius;
+	int color;
+} spheres[NUM_SPHERES] = {
+{
+	.center.x=0,
+	.center.y=-1,
+	.center.z=3,
+	.radius=1,
+	.color=1,
+},
+{
+	.center.x=2,
+	.center.y=0,
+	.center.z=4,
+	.radius=1,
+	.color=2,
+},
+{
+	.center.x=-2,
+	.center.y=0,
+	.center.z=4,
+	.radius=1,
+	.color=4,
+}
+};
+
+float dot(struct vector *a, struct vector *b) {
+
+	return a->x*b->x + a->y*b->y + a->z*b->z;
+
+}
+
+static int intersect_ray_sphere(
+	struct vector *o, struct vector *d, int s,
+	float *t1, float *t2) {
+
+	float r=spheres[s].radius;
+	struct vector c0;
+	float a,b,c;
+	float discriminant;
+
+	c0.x=o->x-spheres[s].center.x;
+	c0.y=o->y-spheres[s].center.y;
+	c0.z=o->z-spheres[s].center.z;
+
+	a=dot(d,d);
+	b=2*dot(&c0,d);
+	c=dot(&c0,&c0)-r*r;
+
+	discriminant=b*b-4*a*c;
+	if (discriminant<0) {
+		*t1=INFINITY;
+		*t2=INFINITY;
+	}
+
+	*t1=(-b+sqrt(discriminant))/(2*a);
+	*t2=(-b-sqrt(discriminant))/(2*a);
+
+	return 0;
+}
+
+static int trace_ray(struct vector *o, struct vector *d, int t_min, int t_max) {
+
+	float closest_t=INFINITY;
+	int closest_sphere=-1;
+	int s;
+	float t1,t2;
+
+	for(s=0;s<NUM_SPHERES;s++) {
+		intersect_ray_sphere(o,d,s,&t1,&t2);
+		if ((t1>t_min) && (t1<t_max) && (t1<closest_t)) {
+			closest_t=t1;
+			closest_sphere=s;
+		}
+		if ((t2>t_min) && (t2<t_max) && (t2<closest_t)) {
+			closest_t=t2;
+			closest_sphere=s;
+		}
+
+	}
+
+	if (closest_sphere==-1) {
+		return 15;
+	}
+	return spheres[closest_sphere].color;
+}
+
+int main(int argc, char **argv) {
+
+	int ch;
+	int xx,yy,color;
+	struct vector d,o;
+
+	o.x=0;
+	o.y=0;
+	o.z=0;
+
+
+	grsim_init();
+
+	gr();
+
+	clear_screens();
+
+	ram[DRAW_PAGE]=0;
+
+	frame=0;
+
+	for(xx=-c_w/2;xx<c_w/2;xx++) {
+		for(yy=-c_h/2;yy<c_h/2;yy++) {
+			canvas_to_viewport(xx,yy,&d);
+			color=trace_ray(&o,&d,1,100000);
+			color_equals(color);
+			plot((c_w/2)+xx,47-((c_h/2)+yy));
+		}
+	}
+
+	grsim_update();
+
+	while(1) {
+
+		usleep(60000);
+
+		ch=grsim_input();
+		if (ch=='q') return 0;
+		if (ch==27) return 0;
+	}
+
+	return 0;
+}