diff options
Diffstat (limited to 'main.c')
| -rw-r--r-- | main.c | 272 |
1 files changed, 0 insertions, 272 deletions
@@ -1,272 +0,0 @@ -#include <limits.h> -#include <float.h> -#include <stdlib.h> -#include <stdio.h> -#include <stdint.h> -#include <string.h> -#include <math.h> - -typedef enum { - kRetSucc, - kRetFail, -} Ret; - -typedef struct { - int width; - int height; - float *buffer; -} Picture; - -typedef struct { - float r; - float g; - float b; -} Color; - -typedef struct { - int x; - int y; -} Vec2i; - - -Picture new_picture(int width, int height) { - Picture ret; - ret.width = width; - ret.height = height; - ret.buffer = malloc(sizeof(float) * width * height * 3); - return ret; -} - -void delete_picture(Picture pic) { - free(pic.buffer); -} - -void set_pixel(Picture pic, Vec2i pos, Color c) { - int idx = pos.y * pic.width * 3 + pos.x * 3; - pic.buffer[idx] = c.b; - pic.buffer[idx+1] = c.g; - pic.buffer[idx+2] = c.r; -} - -Ret fwrite_word16le(FILE* fp, uint16_t x) { - uint8_t buf[2]; - buf[0] = x & 0xff; - buf[1] = (x >> 8) & 0xff; - int r = fwrite(buf, 1, 2, fp); - if (r != 2) return kRetFail; - return kRetSucc; -} - -Ret fwrite_word32le(FILE* fp, uint32_t x) { - Ret ret; - uint16_t buf[2]; - - buf[0] = x & 0xffff; - buf[1] = (x >> 16) & 0xffff; - ret = fwrite_word16le(fp, buf[0]); - if (ret != kRetSucc) return ret; - ret = fwrite_word16le(fp, buf[1]); - if (ret != kRetSucc) return ret; - return kRetSucc; -} - - -Ret writeBMP(const char* filename, Picture pic) { - Ret ret = kRetFail; - FILE *fp = NULL; - uint8_t *databuf = NULL; - - fp = fopen(filename, "wb"); - if (!fp) goto end; - - int row_data_len = 3 * pic.width; - int padding = (4 - row_data_len % 4) % 4; - int row_len = row_data_len + padding; - int img_len = row_len * pic.height; - int file_len = 53 + img_len; - - ret = fwrite_word16le(fp, 0x4d42); - if (ret != kRetSucc) goto end; - ret = fwrite_word32le(fp, file_len); - if (ret != kRetSucc) goto end; - ret = fwrite_word32le(fp, 0); - if (ret != kRetSucc) goto end; - ret = fwrite_word32le(fp, 54); - if (ret != kRetSucc) goto end; - - ret = fwrite_word32le(fp, 40); - if (ret != kRetSucc) goto end; - ret = fwrite_word32le(fp, pic.width); - if (ret != kRetSucc) goto end; - ret = fwrite_word32le(fp, -pic.height); - if (ret != kRetSucc) goto end; - ret = fwrite_word16le(fp, 1); - if (ret != kRetSucc) goto end; - ret = fwrite_word16le(fp, 24); - if (ret != kRetSucc) goto end; - ret = fwrite_word32le(fp, 0); // BI_RGB - if (ret != kRetSucc) goto end; - ret = fwrite_word32le(fp, img_len); - if (ret != kRetSucc) goto end; - ret = fwrite_word32le(fp, 0); - if (ret != kRetSucc) goto end; - ret = fwrite_word32le(fp, 0); - if (ret != kRetSucc) goto end; - ret = fwrite_word32le(fp, 0); - if (ret != kRetSucc) goto end; - ret = fwrite_word32le(fp, 0); - if (ret != kRetSucc) goto end; - - databuf = malloc(img_len); - memset(databuf, 0, img_len); - for (int i = 0; i < pic.height; i++) { - for (int j = 0; j < pic.width * 3; j++) { - int fromidx = i * pic.width * 3 + j; - int toidx = i * row_len + j; - float value = pic.buffer[fromidx]; - if (value < 0) databuf[toidx] = 0; - else if (value > 1.0) { - databuf[toidx] = 255; - } else databuf[toidx] = 255 * value; - } - } - if (fwrite(databuf, 1, img_len, fp) != img_len) { - ret = kRetFail; - goto end; - } - ret = kRetSucc; - -end: - if (databuf != NULL) free(databuf); - if (fp != NULL) fclose(fp); - return ret; -} - -typedef struct { - float x; - float y; - float z; -} Vec3f; - -Vec3f screen_proj(int width, int height, Vec2i sp) { - Vec3f ret; - float maxlen = width > height ? width : height; - ret.z = 1; - ret.x = (sp.x - width / 2.0) / maxlen; - ret.y = (-sp.y + height / 2.0) / maxlen; - return ret; -} - -Color icolor(int r, int g, int b) { - return (Color){.r = r/255.0, .g = g/255.0, .b = b/255.0}; -} - -typedef struct { - Vec3f center; - float r; - Color color; -} Ball; - -Ball balls[] = { - { - .center = {.x = 0, .y = -1, .z = 3}, - .r = 1, - }, - { - .center = {.x = 2, .y = 0, .z = 4}, - .r = 1, - }, - { - .center = {.x = -2, .y = 0, .z = 4}, - .r = 1, - }, -}; - - -Color gBackgroupColor = {0,0,0}; - -void init_color() { - balls[0].color = icolor(0x95, 0xe1, 0xe3); - balls[1].color = icolor(0xfc, 0xe3, 0x8a); - balls[2].color = icolor(0xf3, 0x81, 0x81); - gBackgroupColor = icolor(0xea, 0xea, 0xea); -} - -Vec3f vec3f_sub(Vec3f lhs, Vec3f rhs) { - return (Vec3f){ - .x = lhs.x - rhs.x, - .y = lhs.y - rhs.y, - .z = lhs.z - rhs.z, - }; -} - -float vec3f_dot(Vec3f lhs, Vec3f rhs) { - return lhs.x * rhs.x + lhs.y * rhs.y + lhs.z * rhs.z; -} - -float ball_intersect(Vec3f start, Vec3f ray, Ball *ball) { - Vec3f sc = vec3f_sub(start, ball->center); - float a = vec3f_dot(ray, ray); - float b = 2 * vec3f_dot(sc, ray); - float c = vec3f_dot(sc, sc) - ball->r * ball->r; - float delta = b*b - 4*a*c; - if (delta < 0) { - return -1; - } - float t1 = (-b + sqrt(delta)) / 2*a; - float t2 = (-b - sqrt(delta)) / 2*a; - return t1 < t2 ? t1 : t2; -} - -Color calc_color(Vec3f v) { - Vec3f start = {.x = 0, .y = 0, .z = 0}; - float tmin = 0.1; - float tmax = FLT_MAX; - - int nearest_idx = -1; - float t_nearest = FLT_MAX; - for (int i = 0; i < sizeof(balls) / sizeof(Ball); i++) { - float t = ball_intersect(start, v, &balls[i]); - // printf("t:%f\n", t); - if (t < t_nearest && t < tmax && t > tmin) { - t_nearest = t; - nearest_idx = i; - } - } - if (nearest_idx >= 0) { - return balls[nearest_idx].color; - } else { - return gBackgroupColor; - } -} - -void normalize_picture(Picture pic) { - float maxval = 0; - for (size_t i = 0; i < pic.width * pic.height * 3; i++) { - float val = pic.buffer[i]; - if (val < 0) val = 0; - if (val > maxval) maxval = val; - } - if (maxval < 1.0) return; - for (size_t i = 0; i < pic.width * pic.height * 3; i++) { - pic.buffer[i] = pic.buffer[i] / maxval; - } -} - -int main() { - init_color(); - int img_w = 1280; - int img_h = 720; - Picture pic = new_picture(img_w, img_h); - for (int x = 0; x < img_w; x++) { - for (int y = 0; y < img_h; y++) { - Vec2i screen_pos = {x, y}; - Vec3f v = screen_proj(img_w, img_h, screen_pos); - set_pixel(pic, screen_pos, calc_color(v)); - } - } - writeBMP("test.bmp", pic); - delete_picture(pic); - return 0; -} - |