external/glfw3_glew_clear/main.cpp

Copyright Matus Chochlik. Distributed under the Boost Software License, Version 1.0. See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt

#include <GL/glew.h>
 
#include <oglplus/gl_api.hpp>
 
#include <eagine/scope_exit.hpp>
 
#include <GLFW/glfw3.h>
 
#include <iostream>
#include <stdexcept>
 
static void run_loop(GLFWwindow* window, int width, int height) {
    using namespace eagine::oglp;
 
    gl_api gl;
 
    if(gl.operations().clear) {
 
        gl.clear_color(0.3F, 0.3F, 0.9F, 0.0F);
        gl.clear_depth(1);
 
        while(true) {
            glfwPollEvents();
 
            if(glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS) {
                glfwSetWindowShouldClose(window, 1);
                break;
            }
 
            if(glfwWindowShouldClose(window)) {
                break;
            }
 
            int new_width, new_height;
            glfwGetWindowSize(window, &new_width, &new_height);
            if((width != new_width) || (height != new_height)) {
                width = new_width;
                height = new_height;
            }
 
            gl.viewport(width, height);
 
            gl().clear(gl.color_buffer_bit | gl.depth_buffer_bit);
 
            glfwSwapBuffers(window);
        }
    } else {
        std::cout << "missing required API" << std::endl;
    }
}
 
static void init_and_run() {
    if(!glfwInit()) {
        throw std::runtime_error("GLFW initialization error");
    } else {
        auto ensure_glfw_cleanup = eagine::finally(glfwTerminate);
 
        glfwWindowHint(GLFW_DOUBLEBUFFER, GL_TRUE);
        glfwWindowHint(GLFW_RED_BITS, 8);
        glfwWindowHint(GLFW_BLUE_BITS, 8);
        glfwWindowHint(GLFW_GREEN_BITS, 8);
        glfwWindowHint(GLFW_ALPHA_BITS, 0);
        glfwWindowHint(GLFW_DEPTH_BITS, 24);
        glfwWindowHint(GLFW_STENCIL_BITS, 0);
 
        glfwWindowHint(GLFW_SAMPLES, GLFW_DONT_CARE);
 
        int width = 800, height = 600;
 
        GLFWwindow* window =
          glfwCreateWindow(width, height, "OGLplus example", nullptr, nullptr);
 
        if(!window) {
            throw std::runtime_error("Error creating GLFW window");
        } else {
            glfwMakeContextCurrent(window);
            glewExperimental = GL_TRUE;
            GLenum init_result = glewInit();
            glGetError();
            if(init_result != GLEW_OK) {
                throw std::runtime_error("OpenGL/GLEW initialization error.");
            } else {
                run_loop(window, width, height);
            }
        }
    }
}
 
auto main() -> int {
    try {
        init_and_run();
        return 0;
    } catch(std::runtime_error& sre) {
        std::cerr << "Runtime error: " << sre.what() << std::endl;
    } catch(std::exception& se) {
        std::cerr << "Unknown error: " << se.what() << std::endl;
    }
    return 1;
}