149 lines
3.7 KiB
C
149 lines
3.7 KiB
C
#define GL_GLEXT_PROTOTYPES
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#include <stdio.h>
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#include <time.h>
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#include <stdlib.h>
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#include <GL/gl.h>
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#include <SDL3/SDL.h>
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void checkGlError() {
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const char *err = SDL_GetError();
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if (*err != 0) {
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printf("OpenGL error: %s", err);
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}
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}
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GLuint compile_shader(GLuint type, const char *src) {
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GLuint id = glCreateShader(GL_FRAGMENT_SHADER);
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glShaderSource(id, 1, &src, 0);
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glCompileShader(id);
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int result;
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glGetShaderiv(id, GL_COMPILE_STATUS, &result);
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if (result == GL_FALSE) {
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int length;
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glGetShaderiv(id, GL_INFO_LOG_LENGTH, &result);
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char *message = alloca(length * sizeof(char));
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glGetShaderInfoLog(id, length, &length, message);
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printf("failed to compile %s shader\n", type == GL_VERTEX_SHADER ? "vertex" : "fragment");
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printf("%s\n", message);
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glDeleteShader(id);
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return 0;
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}
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return id;
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}
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GLuint create_shader(const char *fragment_src) {
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GLuint program = glCreateProgram();
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GLuint fragment_shader = compile_shader(GL_FRAGMENT_SHADER, fragment_src);
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glAttachShader(program, fragment_shader);
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glLinkProgram(program);
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glValidateProgram(program);
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glDeleteShader(fragment_shader);
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return program;
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}
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GLuint load_shader(const char *path) {
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FILE *handle = fopen(path, "r");
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fseek(handle, 0L, SEEK_END);
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long length = ftell(handle);
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fseek(handle, 0L, SEEK_SET);
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char *string = malloc(length * sizeof(char));
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if (!fread(string, sizeof(char), length, handle)) {
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printf("failed to read shader file");
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exit(1);
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}
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fclose(handle);
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GLuint shader = create_shader(string);
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free(string);
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return shader;
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}
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struct timespec program_start;
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void init_timer() {
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clock_gettime(CLOCK_MONOTONIC, &program_start);
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}
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double time_since_start() {
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struct timespec now;
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clock_gettime(CLOCK_MONOTONIC, &now);
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return (now.tv_sec - program_start.tv_sec) +
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(now.tv_nsec - program_start.tv_nsec) / 1e9;
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}
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int main() {
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init_timer();
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printf("Good Morning 🍵\n");
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SDL_Init(SDL_INIT_VIDEO);
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SDL_Window* window = SDL_CreateWindow("SDL3 OpenGL Cube",
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800, 600, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);
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if (!window) {
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printf("CreateWindow Error: %s\n", SDL_GetError());
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SDL_Quit();
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return 1;
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}
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SDL_GLContext glContext = SDL_GL_CreateContext(window);
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if (!glContext) {
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printf("GL Context Error: %s\n", SDL_GetError());
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SDL_DestroyWindow(window);
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SDL_Quit();
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return 1;
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}
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glEnable(GL_DEPTH_TEST);
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SDL_Event e;
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int running = 1;
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GLuint shader = load_shader("fragment.glsl"); //create_shader(fragment_shader_source);
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int w, h;
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double time;
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while (running) {
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while (SDL_PollEvent(&e)) {
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if (e.type == SDL_EVENT_QUIT) running = false;
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if (e.type == SDL_EVENT_WINDOW_RESIZED) {
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SDL_GetWindowSize(window, &w, &h);
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}
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}
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checkGlError();
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// Rendorrrr
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glViewport(0, 0, w, h);
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glClearColor(0.1f, 0.1f, 0.1f, 1.0f); // Dark gray background
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glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
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// Shader parameters.
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glUseProgram(shader);
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int uniform_WindowSize = glGetUniformLocation(shader, "WindowSize");
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glUniform2f(uniform_WindowSize, w, h);
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time = time_since_start();
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int uniform_time = glGetUniformLocation(shader, "time");
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glUniform1f(uniform_time, (float)time);
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// Draw quad.
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glBegin(GL_QUADS);
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glVertex2f(-1, 1);
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glVertex2f(-1,-1);
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glVertex2f( 1,-1);
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glVertex2f( 1, 1);
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glEnd();
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SDL_GL_SwapWindow(window);
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}
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checkGlError();
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}
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