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#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include "3dmath.h"
#define WIDTH 1080
#define HEIGHT 1080
#define BUFFER_SIZE (WIDTH * HEIGHT * 4)
#define LENGTH(array) (sizeof(array) / sizeof(array[0]))
#define MAX(x, y) (x > y ? x : y)
#define MIN(x, y) (x < y ? x : y)
typedef struct {
float position[3];
float radius;
float diffuse[3];
} Object;
typedef struct {
float position[3];
float diffuse[3];
} Light;
static unsigned char buffer[BUFFER_SIZE];
static Object objects[] = {{.position={-1.414, -1, -3}, .radius=1, .diffuse={.8, 0, .8}},
{.position={0, 1, -5}, .radius=1, .diffuse={0, .8, .8}},
{.position={1.414, -1, -3}, .radius=1, .diffuse={.8, .8, 0}}};
static Light lights[] = {{.position={-3, 3, -4}, .diffuse={0, .6, .6}},
{.position={0, 30, -4}, .diffuse={1, 1, 1}}};
static void
trace(float s[3], float d[3], float pixel[3], int n) {
int i, j, k, m;
float l[3], r[3], t, y[3];
for(j = 0; j < LENGTH(objects); ++j) {
t = sphere_intersect(y, r, s, d, objects[j].position, objects[j].radius);
if(t > 0) {
for(m = 0; m < LENGTH(lights); ++m) {
for(i = 0; i < 3; ++i)
l[i] = lights[m].position[i] - y[i];
normalize(l);
for(k = 0; k < 3; ++k)
pixel[k] += lights[m].diffuse[k] * objects[j].diffuse[k] * (MAX(dot(l, r), 0)) / (1 << n);
trace(y, r, pixel, n + 1);
}
} else {
continue;
}
}
}
static void
display(void) {
static float s[3] = {0, 0, 0};
int i, j;
float x, y;
float d[3];
float pixel[3];
memset(buffer, '\0', sizeof(buffer));
for(i = 0; i < BUFFER_SIZE; i += 4) {
x = (i / 4) % WIDTH - WIDTH / 2;
y = (i / 4) / WIDTH - HEIGHT / 2;
d[0] = x / (WIDTH / 2);
d[1] = y / (HEIGHT / 2);
d[2] = -1;
normalize(d);
memset(pixel, '\0', sizeof(pixel));
trace(s, d, pixel, 1);
for(j = 0; j < 3; ++j)
buffer[i + j] = MIN(255 * pixel[j], 255);
}
glDrawPixels(WIDTH, HEIGHT, GL_BGRA, GL_UNSIGNED_BYTE, buffer);
glutSwapBuffers();
}
static void
reshape(int w, int h) {
glViewport(0, 0, w, h);
}
static void
keyboard(unsigned char key, int x, int y) {
if(key == 27)
exit(0);
}
static int
init(int argc, char **argv, int w, int h) {
glutInit(&argc, argv);
glutInitWindowPosition(0, 0);
glutInitWindowSize(w, h);
glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
glutCreateWindow(argv[0]);
glDepthMask(0);
glDisable(GL_DEPTH_TEST);
glDisable(GL_BLEND);
return 0;
}
int
main(int argc, char **argv) {
if (init(argc, argv, WIDTH, HEIGHT))
return 1;
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutKeyboardFunc(keyboard);
glutMainLoop();
return 0;
}
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