Command line tool to test shader compiler (using OpenGL + SDL2).

main.c

/*
Command line tool to test shader compiler (using OpenGL + SDL2).
Run it inside folder that contains shader files.
If filename consists "frag" then it treat as fragment shader.
If filename consists "vert" then it treat as vertex shader.
If filename consists "geo" then it treat as geometry shader.

Build:
gcc main.c -o compile_shader -lGL `sdl2-config --cflags --libs`
*/
#include <GL/gl.h>
#include <SDL2/SDL.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <dirent.h>

// Function to read shader source from a file
char* readShaderSource(const char* shaderFile) {
    FILE* file = fopen(shaderFile, "rb");
    if (!file) {
        printf("Error: Could not open shader file %s\n", shaderFile);
        return NULL;
    }
    fseek(file, 0, SEEK_END);
    long length = ftell(file);
    fseek(file, 0, SEEK_SET);
    char* source = (char*)malloc(length + 1);
    fread(source, 1, length, file);
    source[length] = '\0';
    fclose(file);
    return source;
}

// Function to compile a shader
GLuint compileShader(const char* shaderFile, GLenum shaderType) {
    // Read the shader source from file
    char* shaderSource = readShaderSource(shaderFile);
    if (!shaderSource) {
        return 0;
    }

    // Create and compile the shader
    GLuint shader = glCreateShader(shaderType);
    glShaderSource(shader, 1, (const char**)&shaderSource, NULL);
    glCompileShader(shader);

    // Check for compilation errors
    GLint compileStatus;
    glGetShaderiv(shader, GL_COMPILE_STATUS, &compileStatus);
    printf("\n--------------------------------------------------------------------\nCompiling %s ...\n", shaderFile);
    if (compileStatus == GL_FALSE) {
        GLint logLength;
        glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &logLength);
        char* infoLog = (char*)malloc(logLength);
        glGetShaderInfoLog(shader, logLength, NULL, infoLog);
        // printf("Error compiling shader (%s): %s\n", shaderFile, infoLog);
        printf("%s", infoLog);
        free(infoLog);
        glDeleteShader(shader);
        free(shaderSource);
        return 0;
    }

    // Clean up and return the shader ID
    free(shaderSource);
    return shader;
}

int main() {
    // Initialize SDL
    if (SDL_Init(SDL_INIT_VIDEO) < 0)
    {
        fprintf(stderr, "Failed to initialize SDL: %s\n", SDL_GetError());
        return -1;
    }

    // Set SDL to use an OpenGL context (version 2.1 for compatibility with OpenGL 2.1)
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 2);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 1);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);

    // Create a window with an OpenGL context
    SDL_Window *window = SDL_CreateWindow(
        "Shader Compile Test",
        SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
        640, 480,
        SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN);

    if (!window)
    {
        fprintf(stderr, "Failed to create SDL window: %s\n", SDL_GetError());
        SDL_Quit();
        return -1;
    }

    SDL_GLContext glContext = SDL_GL_CreateContext(window);
    if (!glContext)
    {
        fprintf(stderr, "Failed to create OpenGL context: %s\n", SDL_GetError());
        SDL_DestroyWindow(window);
        SDL_Quit();
        return -1;
    }

    // Open the directory specified by the user
    DIR *dir = opendir(".");
    if (dir == NULL)
    {
        perror("Unable to open directory");
        return 1;
    }

    struct dirent *entry;
    // Loop through directory entries
    while ((entry = readdir(dir)) != NULL)
    {
        // Check if 'frag' is in the filename
        if (strstr(entry->d_name, "frag") != NULL) {
            printf("Result %s %s\n", entry->d_name, compileShader(entry->d_name, GL_FRAGMENT_SHADER) ? "OK" : "FAIL");
        } else if (strstr(entry->d_name, "vert") != NULL) {
            printf("Result %s %s\n", entry->d_name, compileShader(entry->d_name, GL_VERTEX_SHADER) ? "OK" : "FAIL");
        } else if (strstr(entry->d_name, "geo") != NULL) {
            printf("Result %s %s\n", entry->d_name, compileShader(entry->d_name, GL_GEOMETRY_SHADER_EXT) ? "OK" : "FAIL");
        }
    }
    // Close the directory
    closedir(dir);
    return 0;
}