framebuffer.cpp

#include "framebuffer.h"
#include <iostream>
#include "utils.h"

FrameBuffer::FrameBuffer(QOpenGLFunctions_3_3_Core *context,
                         unsigned int width, unsigned int height,
                         float devicePixelRatio)
    : glContext(context), m_frameBuffer(-1),
      m_outputTexture(context), m_depthRenderBuffer(-1),
      m_width(width), m_height(height),
      m_devicePixelRatio(devicePixelRatio), m_created(false)
{}

void FrameBuffer::resize(unsigned int width, unsigned int height,
                         float devicePixelRatio) {
    m_width = width;
    m_height = height;
    m_devicePixelRatio = devicePixelRatio;
}

void FrameBuffer::create() {
    // Initialize the frame buffers and render textures
    glContext->glGenFramebuffers(1, &m_frameBuffer);
    glContext->glGenRenderbuffers(1, &m_depthRenderBuffer);
    m_outputTexture.create(nullptr, GL_RGB, GL_RGB);

    glContext->glBindFramebuffer(GL_FRAMEBUFFER, m_frameBuffer);

    // Set up our texture to an empty image with a width and
    // height equal to our own.
    m_outputTexture.bufferPixelData(m_width * m_devicePixelRatio,
                           m_height * m_devicePixelRatio,
                           GL_RGB, GL_RGB, nullptr);

    // Initialize our depth buffer
    glContext->glBindRenderbuffer(GL_RENDERBUFFER, m_depthRenderBuffer);
    glContext->glRenderbufferStorage(GL_RENDERBUFFER,
                                     GL_DEPTH_COMPONENT,
                                     m_width * m_devicePixelRatio,
                                     m_height * m_devicePixelRatio);
    glContext->glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, m_depthRenderBuffer);

    // Set m_renderedTexture as the color output of our frame buffer
    glContext->glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, m_outputTexture.getHandle(), 0);

    // Sets the color output of the fragment shader to be stored in GL_COLOR_ATTACHMENT0,
    // which we previously set to m_renderedTexture
    GLenum drawBuffers[1] = {GL_COLOR_ATTACHMENT0};
    glContext->glDrawBuffers(1, drawBuffers); // "1" is the size of drawBuffers

    m_created = true;
    if(glContext->glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
    {
        m_created = false;
        std::cout << "Frame buffer did not initialize correctly..." << std::endl;
        printGLErrorLog();
    }
}

void FrameBuffer::destroy() {
    if(m_created) {
        m_created = false;
        glContext->glDeleteFramebuffers(1, &m_frameBuffer);
        glContext->glDeleteRenderbuffers(1, &m_depthRenderBuffer);
        m_outputTexture.destroy();
    }
}

void FrameBuffer::bindFrameBuffer() {
    glContext->glBindFramebuffer(GL_FRAMEBUFFER, m_frameBuffer);
}

void FrameBuffer::bindToTextureSlot(unsigned int slot) {
    m_textureSlot = slot;
    m_outputTexture.bind(slot);
}

unsigned int FrameBuffer::getTextureSlot() const {
    return m_textureSlot;
}