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Examples/OpenGL/cube/src/main.cpp

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C++
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#include <iostream>
#include <glad/glad.h>
#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include <fstream>
#include <chrono>
#include <string>
#include <map>
#include "shader.hpp"
// void GLAPIENTRY MessageCallback(GLenum source,
// GLenum type,
// GLuint id,
// GLenum severity,
// GLsizei length,
// const GLchar* message,
// const void* userParam) {
// fprintf(stderr, "GL CALLBACK: %s type = 0x%x, severity = 0x%x, message = %s\n",
// (type == GL_DEBUG_TYPE_ERROR ? "** GL ERROR **" : "" ),
// type, severity, message);
// }
class Game {
public:
SDL_Window* window = nullptr;
SDL_GLContext glContext = nullptr;
bool isWindowClosed = true;
};
int main(int argc, char** argv) {
Game* game = new Game();
SDL_Init(SDL_INIT_EVERYTHING);
IMG_Init(IMG_INIT_JPG | IMG_INIT_PNG);
SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_ALPHA_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_BUFFER_SIZE, 32);
SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);
game->window = SDL_CreateWindow("GL CUBE",
SDL_WINDOWPOS_CENTERED,
SDL_WINDOWPOS_CENTERED,
500, 500,
SDL_WINDOW_OPENGL);
game->glContext = SDL_GL_CreateContext(game->window);
SDL_GL_SetSwapInterval(0);
gladLoadGLLoader(SDL_GL_GetProcAddress);
// SDL_WarpMouseInWindow(m_window, width / 2, height / 2);
// SDL_SetRelativeMouseMode(SDL_TRUE);
game->isWindowClosed = false;
// Set GL error handling callback
// glEnable(GL_DEBUG_OUTPUT);
// glDebugMessageCallback(MessageCallback, 0);
// Set GL clear colour (light blue)
glClearColor(0.1f, 0.45f, 0.9f, 1.0f);
// GL Screen coordinates of a 2D triangle followed by the colour and the texture coordinates
GLint numOfVerticies = 288;
float vertices[] = {
// Positions Colour Texture
-0.5f, -0.5f, -0.5f, 1.0f, 1.0f, 1.0f, 0.0f, 0.0f,
0.5f, -0.5f, -0.5f, 1.0f, 1.0f, 1.0f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f,
-0.5f, 0.5f, -0.5f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 1.0f, 1.0f, 1.0f, 0.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 1.0f, 1.0f, 1.0f, 0.0f, 0.0f,
0.5f, -0.5f, 0.5f, 1.0f, 1.0f, 1.0f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f,
-0.5f, 0.5f, 0.5f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 1.0f, 1.0f, 1.0f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 1.0f, 1.0f, 1.0f, 1.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 1.0f, 1.0f, 1.0f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 1.0f, 1.0f, 1.0f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f, 1.0f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f,
0.5f, -0.5f, -0.5f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f,
0.5f, -0.5f, -0.5f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f,
0.5f, -0.5f, 0.5f, 1.0f, 1.0f, 1.0f, 0.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f, 1.0f, 1.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f,
0.5f, -0.5f, -0.5f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f,
0.5f, -0.5f, 0.5f, 1.0f, 1.0f, 1.0f, 1.0f, 0.0f,
0.5f, -0.5f, 0.5f, 1.0f, 1.0f, 1.0f, 1.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 1.0f, 1.0f, 1.0f, 0.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f,
-0.5f, 0.5f, -0.5f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f, 1.0f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f, 1.0f, 1.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 1.0f, 1.0f, 1.0f, 0.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f
};
// Element array - order of verticies drawn
GLuint elements[] = {
0, 1, 2,
2, 3, 0
};
// Generate a vertex array object
GLuint vao;
glGenVertexArrays(1, &vao);
// Bind array to GPU
glBindVertexArray(vao);
// Generate a vertex buffer object
GLuint vbo;
glGenBuffers(1, &vbo);
// Bind buffer to the GPU
glBindBuffer(GL_ARRAY_BUFFER, vbo);
// Copy vertex data to the vertex buffer already on the GPU
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices[0]) * numOfVerticies, vertices, GL_STATIC_DRAW);
// Generate another vertex buffer for the element array buffer
GLuint ebo;
glGenBuffers(1, &ebo);
// Bind buffer to the GPU
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
// Copy buffer data to the buffer already on the GPU
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(elements), elements, GL_STATIC_DRAW);
// Load, compile, apply and link shader programs
Shader simpleShader;
simpleShader.load("./resources/shaders/simple").attatch().link().use();
// Load texture from file
SDL_Surface* sur = IMG_Load("./resources/textures/dirt.png");
if (sur == NULL) {
std::cerr << "Failed to load image: " << IMG_GetError() << std::endl;
} else {
std::cout << "Loaded texture 'dirt.png'" << std::endl;
}
// Set up a GL texture
GLuint tex;
glBindTexture(GL_TEXTURE_2D, tex);
// Set mag and min filtering levels
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
// Passes SDL texture into the texture buffer for GL to use in shaders
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, sur->w, sur->h, 0, GL_RGBA, GL_UNSIGNED_BYTE, sur->pixels);
GLint posAttrib = glGetAttribLocation(simpleShader.getProgram(), "position");
glEnableVertexAttribArray(posAttrib);
glVertexAttribPointer(posAttrib, 3, GL_FLOAT, GL_FALSE,
8*sizeof(float), 0);
GLint colAttrib = glGetAttribLocation(simpleShader.getProgram(), "colour");
glEnableVertexAttribArray(colAttrib);
glVertexAttribPointer(colAttrib, 3, GL_FLOAT, GL_FALSE,
8*sizeof(float), (void*)(3*sizeof(float)));
GLint texAttrib = glGetAttribLocation(simpleShader.getProgram(), "texcoord");
glEnableVertexAttribArray(texAttrib);
glVertexAttribPointer(texAttrib, 2, GL_FLOAT, GL_FALSE,
8*sizeof(float), (void*)(6*sizeof(float)));
// Model matrice
glm::mat4 model = glm::mat4(1.0f);
// Gets uniform for model matrice, to be used later
GLint uniTrans = glGetUniformLocation(simpleShader.getProgram(), "model");
// View matrice
glm::mat4 view = glm::lookAt(
glm::vec3(1.2f, 1.2f, 1.2f),
glm::vec3(0.0f, 0.0f, 0.0f),
glm::vec3(0.0f, 0.0f, 1.0f)
);
// Get uniform and send it to the GPU
GLint uniView = glGetUniformLocation(simpleShader.getProgram(), "view");
glUniformMatrix4fv(uniView, 1, GL_FALSE, glm::value_ptr(view));
// Projection matrice
glm::mat4 proj = glm::perspective(glm::radians(45.0f), 1.0f, 1.0f, 10.0f);
// Get uniform and send it to the GPU
GLint uniProj = glGetUniformLocation(simpleShader.getProgram(), "proj");
glUniformMatrix4fv(uniProj, 1, GL_FALSE, glm::value_ptr(proj));
// Enable depth buffer
glEnable(GL_DEPTH_TEST);
std::chrono::high_resolution_clock timer;
auto FPSCalculateLast = timer.now();
auto FPSClock = SDL_GetTicks();
auto UpdateClock = SDL_GetTicks();
SDL_Event event;
while (!game->isWindowClosed) {
// Measure fps
if (SDL_GetTicks() - FPSClock >= 1000) {
auto deltaTime = std::chrono::duration_cast<std::chrono::nanoseconds>(timer.now() - FPSCalculateLast).count();
std::cout << "FPS: " << (int)(1 / ((float)deltaTime * 1e-9)) << std::endl;
FPSClock = SDL_GetTicks();
}
FPSCalculateLast = timer.now();
// Input handling
while (SDL_PollEvent(&event) != 0)
if (event.type == SDL_QUIT)
game->isWindowClosed = true;
// Rotate cube
if (SDL_GetTicks() - UpdateClock >= 10) {
model = glm::rotate(model, glm::radians(1.0f), glm::vec3(0.0f, 0.0f, 1.0f));
model = glm::rotate(model, glm::radians(1.0f), glm::vec3(1.0f, 0.0f, 0.0f));
glm::vec4 result = model * glm::vec4(1.0f, 0.0f, 0.0f, 1.0f);
glUniformMatrix4fv(uniTrans, 1, GL_FALSE, glm::value_ptr(model));
UpdateClock = SDL_GetTicks();
}
// Clear the screen
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// Draw a triangle from the 3 vertices
// glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
glDrawArrays(GL_TRIANGLES, 0, 36);
// Swap buffers
SDL_GL_SwapWindow(game->window);
}
game->isWindowClosed = true;
SDL_GL_DeleteContext(game->glContext);
SDL_DestroyWindow(game->window);
SDL_Quit();
return 0;
}
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