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#include <iostream>
// GLAD
#define GLAD_GL_IMPLEMENTATION
#include <glad/gl.h>
// GLFW
#include <GLFW/glfw3.h>
// This example is taken from http://learnopengl.com/
// http://learnopengl.com/code_viewer.php?code=getting-started/hellowindow2
// The code originally used GLEW, I replaced it with Glad
// Compile:
// g++ example/c++/hellowindow2.cpp -Ibuild/include build/src/glad.c -lglfw -ldl
// Function prototypes
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode);
// Window dimensions
const GLuint WIDTH = 800, HEIGHT = 600;
#ifdef GLAD_OPTION_GL_DEBUG
// Define a custom callback for demonstration purposes
void pre_gl_call(const char *name, void *funcptr, int len_args, ...) {
#ifdef GLAD_OPTION_GL_MX
printf("Current GL Context: %p -> ", gladGetGLContext());
#endif
printf("Calling: %s at %p (%d arguments)\n", name, funcptr, len_args);
}
#endif
// The MAIN function, from here we start the application and run the game loop
int main()
{
std::cout << "Starting GLFW context, OpenGL 3.3" << std::endl;
// Init GLFW
glfwInit();
// Set all the required options for GLFW
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);
// Create a GLFWwindow object that we can use for GLFW's functions
GLFWwindow* window = glfwCreateWindow(WIDTH, HEIGHT, "LearnOpenGL", NULL, NULL);
glfwMakeContextCurrent(window);
if (window == NULL)
{
std::cout << "Failed to create GLFW window" << std::endl;
glfwTerminate();
return -1;
}
// Set the required callback functions
glfwSetKeyCallback(window, key_callback);
#ifdef GLAD_OPTION_GL_LOADER
printf("Using internal loader.\n");
#endif
#ifdef GLAD_OPTION_GL_MX
GladGLContext context = {};
#ifdef GLAD_OPTION_GL_LOADER
int version = gladLoaderLoadGLContext(&context);
#else
int version = gladLoadGLContext(&context, glfwGetProcAddress);
#endif
#else
#ifdef GLAD_OPTION_GL_LOADER
int version = gladLoaderLoadGL();
#else
int version = gladLoadGL(glfwGetProcAddress);
#endif
#endif
if (version == 0)
{
std::cout << "Failed to initialize OpenGL context" << std::endl;
return -1;
}
std::cout << "Loaded OpenGL " << GLAD_VERSION_MAJOR(version) << "." << GLAD_VERSION_MINOR(version) << std::endl;
#ifdef GLAD_OPTION_GL_DEBUG
// before every opengl call call pre_gl_call
glad_set_gl_pre_callback(pre_gl_call);
// don't use the callbacks for glClear and glClearColor
#ifdef GLAD_OPTION_GL_MX_GLOBAL
glad_debug_glClear = gladGetGLContext()->Clear;
glad_debug_glClearColor = gladGetGLContext()->ClearColor;
#else
glad_debug_glClear = glad_glClear;
glad_debug_glClearColor = glad_glClearColor;
#endif
#endif
// Define the viewport dimensions
glViewport(0, 0, WIDTH, HEIGHT);
// Game loop
while (!glfwWindowShouldClose(window))
{
// Check if any events have been activated (key pressed, mouse moved etc.) and call corresponding response functions
glfwPollEvents();
// Render
// Clear the colorbuffer
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
// Swap the screen buffers
glfwSwapBuffers(window);
}
// Terminates GLFW, clearing any resources allocated by GLFW.
glfwTerminate();
return 0;
}
// Is called whenever a key is pressed/released via GLFW
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode)
{
if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
glfwSetWindowShouldClose(window, GL_TRUE);
}
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