r_gbuffer.cpp

#include <string.h>

#include "r_gbuffer.h"

#include "m_mat.h"

namespace r {

gBuffer::gBuffer()
    : m_fbo(0)
    , m_width(0)
    , m_height(0)
{
    memset(m_textures, 0, sizeof m_textures);
}

gBuffer::~gBuffer() {
    destroy();
}

void gBuffer::destroy() {
    if (m_fbo)
        gl::DeleteFramebuffers(1, &m_fbo);
    if (m_textures[0])
        gl::DeleteTextures(kMax, m_textures);
}

void gBuffer::update(const m::perspective &p) {
    const size_t width = p.width;
    const size_t height = p.height;

    if (m_width == width && m_height != height)
        return;

    const GLenum format = gl::has(gl::ARB_texture_rectangle) ? GL_TEXTURE_RECTANGLE : GL_TEXTURE_2D;
    m_width = width;
    m_height = height;

    // diffuse + specular
    gl::BindTexture(format, m_textures[kColor]);
    gl::TexImage2D(format, 0, GL_RGBA8, m_width, m_height, 0, GL_RGBA, GL_FLOAT, nullptr);

    // normals + specular
    gl::BindTexture(format, m_textures[kNormal]);
    gl::TexImage2D(format, 0, GL_RGBA8, m_width, m_height, 0, GL_RGBA, GL_FLOAT, nullptr);

    // depth
    gl::BindTexture(format, m_textures[kDepth]);
    gl::TexImage2D(format, 0, GL_DEPTH24_STENCIL8,
        m_width, m_height, 0, GL_DEPTH_STENCIL, GL_UNSIGNED_INT_24_8, nullptr);
}

bool gBuffer::init(const m::perspective &p) {
    m_width = p.width;
    m_height = p.height;

    gl::GenFramebuffers(1, &m_fbo);
    gl::BindFramebuffer(GL_DRAW_FRAMEBUFFER, m_fbo);

    gl::GenTextures(kMax, m_textures);

    const GLenum format = gl::has(gl::ARB_texture_rectangle) ? GL_TEXTURE_RECTANGLE : GL_TEXTURE_2D;

    // diffuse + specular
    gl::BindTexture(format, m_textures[kColor]);
    gl::TexImage2D(format, 0, GL_RGBA8, m_width, m_height, 0, GL_RGBA, GL_FLOAT, nullptr);
    gl::TexParameteri(format, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    gl::TexParameteri(format, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    gl::TexParameteri(format, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    gl::TexParameteri(format, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    gl::FramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, format, m_textures[kColor], 0);

    // normals + specular
    gl::BindTexture(format, m_textures[kNormal]);
    gl::TexImage2D(format, 0, GL_RGBA8, m_width, m_height, 0, GL_RGBA, GL_FLOAT, nullptr);
    gl::TexParameteri(format, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    gl::TexParameteri(format, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    gl::TexParameteri(format, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    gl::TexParameteri(format, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    gl::FramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, format, m_textures[kNormal], 0);

    // depth
    gl::BindTexture(format, m_textures[kDepth]);
    gl::TexImage2D(format, 0, GL_DEPTH24_STENCIL8,
        m_width, m_height, 0, GL_DEPTH_STENCIL, GL_UNSIGNED_INT_24_8, nullptr);
    gl::TexParameteri(format, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    gl::TexParameteri(format, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    gl::TexParameteri(format, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    gl::TexParameteri(format, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    gl::FramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT,
        format, m_textures[kDepth], 0);

    static GLenum drawBuffers[] = {
        GL_COLOR_ATTACHMENT0, // diffuse + specular intensity
        GL_COLOR_ATTACHMENT1  // normal + specular power
    };

    gl::DrawBuffers(sizeof drawBuffers / sizeof *drawBuffers, drawBuffers);

    const GLenum status = gl::CheckFramebufferStatus(GL_DRAW_FRAMEBUFFER);
    if (status != GL_FRAMEBUFFER_COMPLETE)
        return false;

    gl::BindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
    return true;
}

void gBuffer::bindWriting() {
    gl::BindFramebuffer(GL_DRAW_FRAMEBUFFER, m_fbo);
}

GLuint gBuffer::texture(gBuffer::textureType type) const {
    return m_textures[type];
}

}