#include "gbuffer.h"
#include "sparrowrenderer.h"
#include "glassert.h"

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

    // - Normal buffer
    glAssert(glGenTextures(1, textures + NORMAL));
    glAssert(glBindTexture(GL_TEXTURE_2D, textures[NORMAL]));
    glAssert(glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB16F, width, height, 0, GL_RGB, GL_FLOAT, NULL));
    glAssert(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST));
    glAssert(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST));
    glAssert(glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, textures[NORMAL], 0));

    // - Color + Specular exponent buffer
    glAssert(glGenTextures(1, textures + COLOR));
    glAssert(glBindTexture(GL_TEXTURE_2D, textures[COLOR]));
    glAssert(glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL));
    glAssert(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST));
    glAssert(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST));
    glAssert(glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, GL_TEXTURE_2D, textures[COLOR], 0));

    // - Specular color + objectId buffer
    glAssert(glGenTextures(1, textures + SPECULAR));
    glAssert(glBindTexture(GL_TEXTURE_2D, textures[SPECULAR]));
    glAssert(glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL));
    glAssert(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST));
    glAssert(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST));
    glAssert(glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT2, GL_TEXTURE_2D, textures[SPECULAR], 0));

    // - depth buffer
    glAssert(glGenTextures(1, textures + DEPTH));
    glAssert(glBindTexture(GL_TEXTURE_2D, textures[DEPTH]));
    glAssert(glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, width, height, 0, GL_DEPTH_COMPONENT, GL_FLOAT, NULL));
    glAssert(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST));
    glAssert(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST));
    glAssert(glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, textures[DEPTH], 0));

    // - Tell OpenGL which color attachments we'll use (of this framebuffer) for rendering
    GLuint attachments[4] = {GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1, GL_COLOR_ATTACHMENT2, GL_DEPTH_ATTACHMENT};
    glAssert(glDrawBuffers(4, attachments));
}

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

void GBuffer::bindTexture(TextureType type, int slot)
{
    glAssert(glActiveTexture(GL_TEXTURE0 + slot));
    glAssert(glBindTexture(GL_TEXTURE_2D, textures[type]));
}