最小可运行示例
main.c
#include <stdio.h>
#include <SDL2/SDL.h>
#define GLEW_STATIC
#include <GL/glew.h>
static const GLuint WIDTH = 512;
static const GLuint HEIGHT = 512;
static const GLchar* vertex_shader_source =
"#version 120\n"
"attribute vec2 coord2d;\n"
"void main() {\n"
" gl_Position = vec4(coord2d, 0.0, 1.0);\n"
"}\n";
static const GLchar* fragment_shader_source =
"#version 120\n"
"void main() {\n"
" gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);\n"
"}\n";
static GLfloat vertices[] = {
0.0, 0.8,
-0.8, -0.8,
0.8, -0.8,
};
GLuint common_get_shader_program(
const char *vertex_shader_source,
const char *fragment_shader_source
) {
GLchar *log = NULL;
GLint log_length, success;
GLuint fragment_shader, program, vertex_shader;
/* Vertex shader */
vertex_shader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertex_shader, 1, &vertex_shader_source, NULL);
glCompileShader(vertex_shader);
glGetShaderiv(vertex_shader, GL_COMPILE_STATUS, &success);
glGetShaderiv(vertex_shader, GL_INFO_LOG_LENGTH, &log_length);
log = malloc(log_length);
if (log_length > 0) {
glGetShaderInfoLog(vertex_shader, log_length, NULL, log);
printf("vertex shader log:\n\n%s\n", log);
}
if (!success) {
printf("vertex shader compile error\n");
exit(EXIT_FAILURE);
}
/* Fragment shader */
fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragment_shader, 1, &fragment_shader_source, NULL);
glCompileShader(fragment_shader);
glGetShaderiv(fragment_shader, GL_COMPILE_STATUS, &success);
glGetShaderiv(fragment_shader, GL_INFO_LOG_LENGTH, &log_length);
if (log_length > 0) {
log = realloc(log, log_length);
glGetShaderInfoLog(fragment_shader, log_length, NULL, log);
printf("fragment shader log:\n\n%s\n", log);
}
if (!success) {
printf("fragment shader compile error\n");
exit(EXIT_FAILURE);
}
/* Link shaders */
program = glCreateProgram();
glAttachShader(program, vertex_shader);
glAttachShader(program, fragment_shader);
glLinkProgram(program);
glGetProgramiv(program, GL_LINK_STATUS, &success);
glGetProgramiv(program, GL_INFO_LOG_LENGTH, &log_length);
if (log_length > 0) {
log = realloc(log, log_length);
glGetProgramInfoLog(program, log_length, NULL, log);
printf("shader link log:\n\n%s\n", log);
}
if (!success) {
printf("shader link error");
exit(EXIT_FAILURE);
}
/* Cleanup. */
free(log);
glDeleteShader(vertex_shader);
glDeleteShader(fragment_shader);
return program;
}
int main(void) {
GLint attribute_coord2d;
GLuint program, vbo;
SDL_Event event;
SDL_GLContext gl_context;
SDL_Window *window;
SDL_Init(SDL_INIT_TIMER | SDL_INIT_VIDEO);
window = SDL_CreateWindow(__FILE__, 0, 0,
WIDTH, HEIGHT, SDL_WINDOW_OPENGL);
gl_context = SDL_GL_CreateContext(window);
glewInit();
/* Shader setup. */
program = common_get_shader_program(vertex_shader_source, fragment_shader_source);
attribute_coord2d = glGetAttribLocation(program, "coord2d");
/* Buffer setup. */
glGenBuffers(1, &vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
glVertexAttribPointer(attribute_coord2d, 2, GL_FLOAT, GL_FALSE, 0, 0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
/* Global draw state */
glUseProgram(program);
glViewport(0, 0, WIDTH, HEIGHT);
glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
/* Main loop. */
while (1) {
glClear(GL_COLOR_BUFFER_BIT);
glEnableVertexAttribArray(attribute_coord2d);
glDrawArrays(GL_TRIANGLES, 0, 3);
glDisableVertexAttribArray(attribute_coord2d);
SDL_GL_SwapWindow(window);
if (SDL_PollEvent(&event) && event.type == SDL_QUIT)
break;
}
/* Cleanup. */
glDeleteBuffers(1, &vbo);
glDeleteProgram(program);
SDL_GL_DeleteContext(gl_context);
SDL_DestroyWindow(window);
SDL_Quit();
return EXIT_SUCCESS;
}
GitHub 上游 https://github.com/cirosantilli/cpp-cheat/blob/7b5ee8a90dc0355e1a0908e9b89cc0f6b5e41e0e/sdl/opengl.c.
编译并运行:
sudo apt-get install libsdl2-dev
gcc -lSDL2 -lGL -lGLEW -o main.out main.c
./main.out
有关 OpenGL 特定部分的更多信息:OpenGL 中“立即模式”是什么意思? https://stackoverflow.com/questions/6733934/what-does-immediate-mode-mean-in-opengl/36166310#36166310
在 Ubuntu 16.04 上测试。