#include "Canvas.hpp"

Canvas::Canvas(GLuint width, GLuint height) :
m_width(width), m_height(height)
{
}

Canvas::~Canvas()
{
}

void Canvas::create()
{
    /* Generation de la texture */
    glGenTextures(1, &m_texture);
    glBindTexture(GL_TEXTURE_2D, m_texture);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, 
                 m_width, m_height, 0, GL_RGBA, 
                 GL_UNSIGNED_BYTE, NULL);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);
    
    /* Generation du Frame Buffer */
    glGenFramebuffers(1, &m_FBO);
    glBindFramebuffer(GL_FRAMEBUFFER, m_FBO);
    glFramebufferTexture(GL_READ_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, m_texture, 0);
    
    glReadBuffer(GL_COLOR_ATTACHMENT0);
}

void Canvas::bind()
{
    glBindFramebuffer(GL_FRAMEBUFFER, m_FBO);
    glBindImageTexture(0, m_texture, 0, GL_FALSE, 0, GL_WRITE_ONLY, GL_RGBA8);
}

void Canvas::unbind()
{
    glBindFramebuffer(GL_FRAMEBUFFER, 0);
    // glBindTexture(GL_TEXTURE_2D, 0);
}

void Canvas::draw()
{
    glBindFramebuffer(GL_READ_FRAMEBUFFER, m_FBO);
    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
    glBlitFramebuffer(
            0, 0, m_width, m_height,
            0, 0, m_width, m_height,
            GL_COLOR_BUFFER_BIT, GL_NEAREST);
    glBindFramebuffer(GL_READ_FRAMEBUFFER, 0);
    glBindTexture(GL_TEXTURE_2D, 0);
}

void Canvas::release()
{
    glDeleteTextures(1, &m_texture);
    glDeleteFramebuffers(1, &m_FBO);  
}