I'm developing a simple application with SDL2 and OpenGL in C++.
The problem is that my program doesn't draw the triangle.
Rect.hpp (The class that draw the triangle):
#ifndef Rect_hpp
#define Rect_hpp
#include <stdio.h>
#include <iostream>
#define GLEW_STATIC
#include <GL/glew.h>
#include <SDL2/SDL.h>
#include "Shaders.hpp"
using namespace std;
extern GLfloat vertices[];
class Rect
{
public:
Rect();
~Rect();
void init();
void draw();
private:
void bind();
GLuint VAO;
GLuint VBO;
GLuint vertexShader;
GLuint fragmentShader;
GLuint shaderProgram;
Shaders shaders;
};
#endif /* Rect_hpp */
Rect.cpp:
#include "Rect.hpp"
GLfloat vertices[] = {
-0.5f, -0.5f, 0.0f,
0.5f, -0.5f, 0.0f,
0.0f, 0.5f, 0.0f,
};
Rect::Rect()
{
VBO = NULL;
vertexShader = NULL;
fragmentShader = NULL;
shaderProgram = NULL;
}
Rect::~Rect()
{
glDeleteShader(vertexShader);
vertexShader = NULL;
glDeleteShader(fragmentShader);
fragmentShader = NULL;
}
void Rect::bind()
{
glBindVertexArray(VAO);
glBindBuffer(GL_ARRAY_BUFFER, VBO); //VBO activation
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(GLfloat (GLvoid*)0);
glEnableVertexAttribArray(0);
glBindVertexArray(0);
}
void Rect::init()
{
//VAO
glGenVertexArrays(1, &VAO); //VAO creation
//VBO
glGenBuffers(1, &VBO); //VBO creation
//SHADER
vertexShader = glCreateShader(GL_VERTEX_SHADER); //vertex shader
glShaderSource(vertexShader, 1, &shaders.vertexSource, NULL);
glCompileShader(vertexShader);
fragmentShader = glCreateShader(GL_FRAGMENT_SHADER); //fragment shader
glShaderSource(fragmentShader, 1, &shaders.fragmentSource, NULL);
glCompileShader(fragmentShader);
shaderProgram = glCreateProgram(); //shader program
glAttachShader(shaderProgram, vertexShader);
glAttachShader(shaderProgram, fragmentShader);
glLinkProgram(shaderProgram);
bind();
}
void Rect::draw()
{
glUseProgram(shaderProgram);
glBindVertexArray(VAO);
glDrawArrays(GL_TRIANGLES, 0, 3);
glBindVertexArray(0);
}
Game.hpp:
#ifndef Game_hpp
#define Game_hpp
#include <stdio.h>
#include <iostream>
#define GLEW_STATIC
#include <GL/glew.h>
#include <SDL2/SDL.h>
#include <SDL2/SDL_opengl.h>
#include <OpenGL/gl3.h>
#include "glm/glm.hpp"
#include "Rect.hpp"
using namespace glm;
using namespace std;
class Game
{
public:
Game(int width, int height);
~Game();
void run();
private:
int _width, _height;
void init();
void loop();
void input();
void draw();
SDL_Window* window;
SDL_GLContext context;
bool isRunning;
SDL_Event e;
Rect* rect;
};
#endif /* Game_hpp */
Game.cpp:
#include "Game.hpp"
Game::Game(int width, int height)
{
_width = width;
_height = height;
window = NULL;
context = NULL;
rect = new Rect();
isRunning = true;
}
Game::~Game()
{
SDL_GL_DeleteContext(context);
context = NULL;
SDL_DestroyWindow(window);
window = NULL;
SDL_Quit();
}
void Game::run()
{
init();
loop();
}
void Game::init()
{
//SDL INIT
SDL_Init(SDL_INIT_EVERYTHING);
//OPENGL ATTRIBUTES
SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);
SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8);
//WINDOW INIT
window = SDL_CreateWindow("OpenGL_GAME_TEST",
SDL_WINDOWPOS_CENTERED,
SDL_WINDOWPOS_CENTERED,
_width,
_height,
SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN);
glViewport(0, 0, _width, _height);
//OPENGL CONTEXT INIT
context = SDL_GL_CreateContext(window);
//GLEW INIT
glewExperimental = GL_TRUE;
if(glewInit() != GLEW_OK)
cout << "ERROR: GLEW initialization failed!" << endl;
//CLASSES INIT
rect->init();
}
void Game::loop()
{
while(isRunning)
{
input();
draw();
}
}
void Game::input()
{
if(SDL_PollEvent(&e))
{
if(e.type == SDL_QUIT) isRunning = false;
if(e.type == SDL_KEYDOWN)
if(e.key.keysym.sym == SDLK_ESCAPE) isRunning = false;
}
}
void Game::draw()
{
//DRAW...
glClearColor(0.2f, 0.4f, 0.5f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
rect->draw();
SDL_GL_SwapWindow(window);
}
Shaders.hpp:
#ifndef Shaders_hpp
#define Shaders_hpp
#include <stdio.h>
#include <iostream>
#include <GL/glew.h>
class Shaders
{
public:
Shaders();
~Shaders();
const GLchar* vertexSource;
const GLchar* fragmentSource;
};
#endif /* Shaders_hpp */
Shaders.cpp:
#include "Shaders.hpp"
Shaders::Shaders()
{
vertexSource = "#version 330 core \n"
"layout (location = 0) in vec3 position; \n"
"void main() \n"
"{ \n"
" gl_Position = vec4(position, 1.0); \n"
"} \n \0";
fragmentSource = "#version 330 core \n"
"out vec4 color \n"
"void main() \n"
"{ \n"
" color = vec4(1.0, 0.5, 0.1, 1.0); \n"
"}; \n \0";
}
Shaders::~Shaders()
{
}
