VoxelEngine/src/graphics/core/GBuffer.cpp

#include "GBuffer.hpp"

#include <GL/glew.h>

#include "debug/Logger.hpp"

static debug::Logger logger("gl-gbuffer");

void GBuffer::createColorBuffer() {
    glGenTextures(1, &colorBuffer);
    glBindTexture(GL_TEXTURE_2D, colorBuffer);
    glTexImage2D(
        GL_TEXTURE_2D,
        0,
        GL_RGB,
        width,
        height,
        0,
        GL_RGB,
        GL_UNSIGNED_BYTE,
        nullptr
    );
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glFramebufferTexture2D(
        GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, colorBuffer, 0
    );
}

void GBuffer::createPositionsBuffer() {
    glGenTextures(1, &positionsBuffer);
    glBindTexture(GL_TEXTURE_2D, positionsBuffer);
    glTexImage2D(
        GL_TEXTURE_2D,
        0,
        GL_RGBA16F,
        width,
        height,
        0,
        GL_RGBA,
        GL_FLOAT,
        nullptr
    );
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glFramebufferTexture2D(
        GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, GL_TEXTURE_2D, positionsBuffer, 0
    );
}

void GBuffer::createNormalsBuffer() {
    glGenTextures(1, &normalsBuffer);
    glBindTexture(GL_TEXTURE_2D, normalsBuffer);
    glTexImage2D(
        GL_TEXTURE_2D,
        0,
        GL_RGBA16F,
        width,
        height,
        0,
        GL_RGBA,
        GL_FLOAT,
        nullptr
    );
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glFramebufferTexture2D(
        GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT2, GL_TEXTURE_2D, normalsBuffer, 0
    );
}

void GBuffer::createDepthBuffer() {
    glGenRenderbuffers(1, &depthBuffer);
    glBindRenderbuffer(GL_RENDERBUFFER, depthBuffer);
    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, width, height);
    glFramebufferRenderbuffer(
        GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthBuffer
    );
}

GBuffer::GBuffer(uint width, uint height) : width(width), height(height) {
    glGenFramebuffers(1, &fbo);
    glBindFramebuffer(GL_FRAMEBUFFER, fbo);

    createColorBuffer();
    createPositionsBuffer();
    createNormalsBuffer();

    GLenum attachments[3] = {
        GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1, GL_COLOR_ATTACHMENT2
    };
    glDrawBuffers(3, attachments);

    createDepthBuffer();

    if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
        logger.error() << "framebuffer is not complete!";
    }
    glBindFramebuffer(GL_FRAMEBUFFER, 0);
}

GBuffer::~GBuffer() {
    glDeleteTextures(1, &colorBuffer);
    glDeleteTextures(1, &positionsBuffer);
    glDeleteTextures(1, &normalsBuffer);
    glDeleteRenderbuffers(1, &depthBuffer);
    glDeleteFramebuffers(1, &fbo);
}

void GBuffer::bind() {
    glBindFramebuffer(GL_FRAMEBUFFER, fbo);
    glClear(GL_COLOR_BUFFER_BIT);
}

void GBuffer::unbind() {
    glBindFramebuffer(GL_FRAMEBUFFER, 0);
}

void GBuffer::bindBuffers() const {
    glActiveTexture(GL_TEXTURE2);
    glBindTexture(GL_TEXTURE_2D, normalsBuffer);

    glActiveTexture(GL_TEXTURE1);
    glBindTexture(GL_TEXTURE_2D, positionsBuffer);

    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, colorBuffer);
}

void GBuffer::resize(uint width, uint height) {
    if (this->width == width && this->height == height) {
        return;
    }
    this->width = width;
    this->height = height;

    glBindFramebuffer(GL_FRAMEBUFFER, fbo);

    glBindRenderbuffer(GL_RENDERBUFFER, depthBuffer);
    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, width, height);
    glBindRenderbuffer(GL_RENDERBUFFER, 0);

    glBindTexture(GL_TEXTURE_2D, colorBuffer);
    glTexImage2D(
        GL_TEXTURE_2D,
        0,
        GL_RGB,
        width,
        height,
        0,
        GL_RGB,
        GL_UNSIGNED_BYTE,
        nullptr
    );
    glFramebufferTexture2D(
        GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, colorBuffer, 0
    );

    glBindTexture(GL_TEXTURE_2D, positionsBuffer);
    glTexImage2D(
        GL_TEXTURE_2D, 0, GL_RGB16F, width, height, 0, GL_RGB, GL_FLOAT, nullptr
    );
    glFramebufferTexture2D(
        GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, GL_TEXTURE_2D, positionsBuffer, 0
    );

    glBindTexture(GL_TEXTURE_2D, normalsBuffer);
    glTexImage2D(
        GL_TEXTURE_2D, 0, GL_RGB16F, width, height, 0, GL_RGB, GL_FLOAT, nullptr
    );
    glFramebufferTexture2D(
        GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT2, GL_TEXTURE_2D, normalsBuffer, 0
    );

    glBindTexture(GL_TEXTURE_2D, 0);
    glBindFramebuffer(GL_FRAMEBUFFER, 0);
}

std::unique_ptr<ImageData> GBuffer::toImage() const {
    auto data = std::make_unique<ubyte[]>(width * height * 3);
    glBindTexture(GL_TEXTURE_2D, colorBuffer);
    glGetTexImage(GL_TEXTURE_2D, 0, GL_RGB, GL_UNSIGNED_BYTE, data.get());
    glBindTexture(GL_TEXTURE_2D, 0);
    return std::make_unique<ImageData>(
        ImageFormat::rgb888, width, height, std::move(data)
    );
}

uint GBuffer::getWidth() const {
    return width;
}

uint GBuffer::getHeight() const {
    return height;
}