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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <pthread.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>
#include "3dmath.h"
#define WIDTH 1000
#define HEIGHT 1000
#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)
#define TAU 6.28318531
typedef struct {
float position[3];
float radius;
float diffuse[3];
} Object;
typedef struct {
float position[3];
float diffuse[3];
} Light;
static unsigned char threaded = 0;
static unsigned char buffer[BUFFER_SIZE];
static Object objects[] = {
{.position={-1.414, -1, -3}, .radius=1, .diffuse={.8, 0, .8}},
{.position={0, 1.414, -3}, .radius=1, .diffuse={0, .8, .8}},
{.position={0, 0, -3}, .radius=.25, .diffuse={.8, .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);
}
}
}
}
static void
trace_line(int l, unsigned char *buf) {
static float s[3] = {0, 0, 0};
float y = l - HEIGHT / 2;
for(int i = 0; i < 4 * WIDTH; i += 4) {
float x = (i / 4) - WIDTH / 2;
float pixel[3];
memset(pixel, '\0', sizeof(pixel));
float d[3];
d[0] = x / (WIDTH / 2);
d[1] = y / (HEIGHT / 2) * ((float)HEIGHT / (float)WIDTH);
d[2] = -1;
normalize(d);
trace(s, d, pixel, 1);
for(int j = 0; j < 3; ++j)
buf[i + j] = MIN(255 * pixel[j], 255);
}
}
static void *
thread(void *arg) {
long line = (long) arg;
trace_line(line, buffer + line * 4 * WIDTH);
pthread_exit(NULL);
}
static void
trace_scene(unsigned char *buf) {
if(threaded) {
pthread_attr_t attr;
pthread_attr_init(&attr);
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
pthread_t threads[HEIGHT];
for(long i = 0; i < HEIGHT; ++i) {
int ret = pthread_create(&threads[i], &attr, thread, (void *)i);
if(ret) {
fprintf(stderr, "pthread_create(): %d\n", ret);
exit(EXIT_FAILURE);
}
}
void *status;
for(long i = 0; i < HEIGHT; ++i)
pthread_join(threads[i], &status);
} else {
for(int i = 0; i < HEIGHT; ++i)
trace_line(i, buffer + i * 4 * WIDTH);
}
}
static void
display(void) {
static int count = 0;
++count;
if(count > 10000)
exit(0);
float time = (float)glutGet(GLUT_ELAPSED_TIME) / 1000;
objects[0].position[0] = 1.5 * cos(time);
objects[0].position[1] = 1.5 * sin(time);
objects[1].position[0] = 1.5 * cos(time + 1/3. * TAU);
objects[1].position[1] = 1.5 * sin(time + 1/3. * TAU);
objects[3].position[0] = 1.5 * cos(time + 2/3. * TAU);
objects[3].position[1] = 1.5 * sin(time + 2/3. * TAU);
objects[2].position[2] = -3 + 2 * sin(time * 2);
trace_scene(buffer);
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) {
switch(key) {
case 27:
exit(EXIT_SUCCESS);
break;
case 't':
if(threaded)
threaded = 0;
else
threaded = 1;
break;
}
}
static int
init(int argc, char **argv, int w, int h) {
glutInit(&argc, argv);
glutInitWindowPosition(0, 0);
glutInitWindowSize(w, h);
glutInitDisplayMode(GLUT_RGB);
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 EXIT_FAILURE;
glutDisplayFunc(display);
glutIdleFunc(display);
glutReshapeFunc(reshape);
glutKeyboardFunc(keyboard);
glutMainLoop();
return EXIT_SUCCESS;
}
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