framebuffer.cpp

// SPDX-License-Identifier: MIT
// Author:  Giovanni Santini
// Mail:    giovanni.santini@proton.me
// Github:  @San7o
 
#include <brenta/renderer/opengl/framebuffer.hpp>
#include <brenta/renderer/opengl/gl.hpp>
#include <brenta/logger.hpp>
#include <brenta/window.hpp>
 
#include <stdexcept>
 
using namespace brenta;
 
int FrameBuffer::tot_memory = 0;
 
FrameBuffer::FrameBuffer(int width, int height, GLenum color_format)
{
  // Save the current state
  GLint old_fbo, old_tex, old_rbo;
  glGetIntegerv(GL_FRAMEBUFFER_BINDING,  &old_fbo);
  glGetIntegerv(GL_TEXTURE_BINDING_2D,   &old_tex);
  glGetIntegerv(GL_RENDERBUFFER_BINDING, &old_rbo);
 
  this->width  = width;
  this->height = height;
  this->color_format = color_format;
 
  glGenFramebuffers(1, &this->id);
  if (this->id == 0)
  {
    ERROR("framebuffer: error generating framebuffer");
    throw std::runtime_error("framebuffer: error generating framebuffer");
  }
  glBindFramebuffer(GL_FRAMEBUFFER, this->id);
  check_error();
 
  glGenTextures(1, &this->texture_id);
  if (this->texture_id == 0)
  {
    ERROR("framebuffer: error generating texture");
    exit(1);
  }
  glBindTexture(GL_TEXTURE_2D, this->texture_id);
  check_error();
 
  glTexImage2D(GL_TEXTURE_2D, 0, this->color_format, width, height, 0, GL_RGB,
               this->channel_type, NULL);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D,
                         this->texture_id, 0);
 
  glGenRenderbuffers(1, &this->render_buffer_id);
  glBindRenderbuffer(GL_RENDERBUFFER, this->render_buffer_id);
  glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, width, height);
  glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT,
                            GL_RENDERBUFFER, this->render_buffer_id);
  check_error();
 
  if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
  {
    ERROR("framebuffer: not complete");
    exit(1);
  }
 
  // Restore old state
  glBindFramebuffer(GL_FRAMEBUFFER, old_fbo);
  glBindTexture(GL_TEXTURE_2D, old_tex);
  glBindRenderbuffer(GL_RENDERBUFFER, old_rbo);
 
  // Update memory for profiling
  int channels          = Gl::get_num_channels(this->color_format);
  int bytes_per_channel = Gl::get_bytes_per_channel(this->channel_type);
  this->memory = channels * bytes_per_channel * width * height;
  FrameBuffer::tot_memory += this->memory;
  
  EVENT(Logger::Event::Lifetime, "framebuffer: initialized");
  return;
}
 
FrameBuffer::~FrameBuffer()
{
  this->destroy();
  return;
}
 
void FrameBuffer::bind() const
{
  glBindFramebuffer(GL_FRAMEBUFFER, this->id);
  check_error();
  return;
}
 
void FrameBuffer::unbind() const
{
  glBindFramebuffer(GL_FRAMEBUFFER, 0);
  check_error();
  return;
}
 
void FrameBuffer::destroy()
{
  if (this->id == 0) return;
  
  glDeleteFramebuffers(1, &this->id);
  glDeleteTextures(1, &this->texture_id);
 
  // Update memory for profiling
  FrameBuffer::tot_memory -= this->memory;
  this->id     = 0;
  this->memory = 0;
 
  EVENT(Logger::Event::Lifetime, "framebuffer: destroyed");
  return;
}
 
void FrameBuffer::rescale(int width, int height)
{
  if (this->width == width && this->height == height)
    return;
  FrameBuffer::tot_memory -= this->memory;
  
  glBindFramebuffer(GL_FRAMEBUFFER, this->id);
 
  this->width  = width;
  this->height = height;
  glBindTexture(GL_TEXTURE_2D, this->texture_id);
  check_error();
 
  glTexImage2D(GL_TEXTURE_2D, 0, this->color_format, width, height, 0,
               this->color_format, this->channel_type, NULL);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D,
                         this->texture_id, 0);
  glBindTexture(GL_TEXTURE_2D, 0);
  check_error();
 
  glBindRenderbuffer(GL_RENDERBUFFER, this->render_buffer_id);
  glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, width, height);
  glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT,
                            GL_RENDERBUFFER, this->render_buffer_id);
  if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
  {
    ERROR("framebuffer: not complete");
    return;
  }
 
  // Update memory for profiling
  int channels          = Gl::get_num_channels(this->color_format);
  int bytes_per_channel = Gl::get_bytes_per_channel(channel_type);
  this->memory = channels * bytes_per_channel * width * height;
  FrameBuffer::tot_memory += this->memory;
  
  return;
}
 
void FrameBuffer::set_color_format(GLenum color_format)
{
  this->color_format = color_format;
  return;
}