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#include "ray.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <pthread.h>
#include <unistd.h>
#include "3dmath.h"
#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
#if __GNUC__ >= 3
# define unlikely(cond) __builtin_expect ((cond), 0)
# define likely(cond) __builtin_expect ((cond), 1)
#else
# define unlikely(cond) (cond)
# define likely(cond) (cond)
#endif
typedef struct {
float position[3];
float radius;
float diffuse[3];
} Object;
typedef struct {
float position[3];
float diffuse[3];
} Light;
typedef struct {
pthread_mutex_t mutex;
unsigned char* buffer;
long next_line;
} ThreadArg;
static float trace_vectors[HEIGHT][WIDTH][3];
static int trace_vectors_initialized;
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 float ambient[3] = {0.2, 0.1, 0.1};
static void
trace(const float s[3], const float d[3], float pixel[3], int n, unsigned int mask) {
float nearest = HUGE_VAL;
int nearest_object = -1;
float nearest_y[3];
float nearest_r[3];
for(int j = 0; j < LENGTH(objects); ++j) {
float r[3], t, y[3];
if ((1 << j) & mask) continue;
t = sphere_intersect(y, r, s, d, objects[j].position, objects[j].radius);
if(likely(t <= 0))
continue;
if (t < nearest) {
nearest = t;
nearest_object = j;
memcpy(nearest_y, y, sizeof(nearest_y));
memcpy(nearest_r, r, sizeof(nearest_y));
}
}
if (nearest_object == -1) return;
for(int m = 0; m < LENGTH(lights); ++m) {
float l[3];
for(int i = 0; i < 3; ++i)
l[i] = lights[m].position[i] - nearest_y[i];
float lr_dot = dot(l, nearest_r);
if (lr_dot > 0) {
float scale = lr_dot / sqrtf(dot(l, l)) / (1 << n);
for(int k = 0; k < 3; ++k) {
float diffuse = lights[m].diffuse[k] * objects[nearest_object].diffuse[k] * scale;
if (diffuse < 0.0f) diffuse = 0.0f;
pixel[k] += diffuse + ambient[k] * objects[nearest_object].diffuse[k];
}
}
}
trace(nearest_y, nearest_r, pixel, n + 1, (1 << nearest_object));
}
static void
trace_line(int l, unsigned char *buf) {
static const float s[3] = {0, 0, 8};
for(int i = 0; i < WIDTH; ++i, buf += 4) {
float pixel[3] = { 0, 0, 0 };
trace(s, trace_vectors[l][i], pixel, 1, 0);
buf[0] = MIN(pixel[0], 1.0f) * 255;
buf[1] = MIN(pixel[1], 1.0f) * 255;
buf[2] = MIN(pixel[2], 1.0f) * 255;
}
}
static void *
thread(void *arg) {
ThreadArg* thread_arg = arg;
for (;;) {
pthread_mutex_lock(&thread_arg->mutex);
if (thread_arg->next_line == HEIGHT) break;
long line = thread_arg->next_line++;
pthread_mutex_unlock(&thread_arg->mutex);
trace_line(line, thread_arg->buffer + line * 4 * WIDTH);
}
pthread_mutex_unlock(&thread_arg->mutex);
return NULL;
}
static void
initialize_trace_vectors(void) {
for(int y = 0; y < HEIGHT; ++y) {
for(int x = 0; x < WIDTH; ++x) {
float* d = trace_vectors[y][x];
d[0] = ((float)x / WIDTH - 0.5f) * 0.5f;
d[1] = ((float)y / HEIGHT - 0.5f) * 0.5f * ((float)HEIGHT / WIDTH);
d[2] = -1;
normalize(d);
}
}
trace_vectors_initialized = 1;
}
void
trace_scene(float time, unsigned char *buf, int threaded) {
if (!trace_vectors_initialized)
initialize_trace_vectors();
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);
if(threaded) {
ThreadArg arg;
memset(&arg, 0, sizeof(arg));
pthread_mutex_init(&arg.mutex, NULL);
arg.buffer = buf;
int num_threads = sysconf(_SC_NPROCESSORS_CONF) - 1;
pthread_t* threads = NULL;
if (num_threads > 0) {
threads = calloc(sizeof(*threads), num_threads);
for (int i = 0; i < num_threads; ++i)
pthread_create(&threads[i], NULL, thread, &arg);
}
thread(&arg);
for(int i = 0; i < num_threads; ++i)
pthread_join(threads[i], NULL);
free(threads);
} else {
for(int i = 0; i < HEIGHT; ++i)
trace_line(i, buf + i * 4 * WIDTH);
}
}
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