panopainter/engine/rtt.cpp

#include "pch.h"
#include "log.h"
#include "rtt.h"

RTT::RTT()
{
    fboID = 0;
    rboID = 0;
    w = 0;
    h = 0;
}

RTT::~RTT()
{
    //destroy();
}

void RTT::destroy()
{
    if (rboID)
    {
        glDeleteRenderbuffers(1, &rboID);
    }
    if (texID)
    {
        unbindTexture();
        glDeleteTextures(1, &texID);
        //LOG("TEX rtt destroy %d", texID)
    }
    if (fboID)
    {
        unbindFramebuffer();
        glDeleteFramebuffers(1, &fboID);
        //LOG("RTT DESTROY %d", fboID);
    }
    texID = 0;
    fboID = 0;
    rboID = 0;
//    w = 0;
//    h = 0;
}

bool RTT::create(int width, int height, int tex/* = -1*/, GLint internal_format)
{
    // Destroy any previously created object
    destroy();

    w = width;
    h = height;

    if (tex == -1)
    {
        glGenTextures(1, &texID);
        //LOG("TEX rtt create %d", texID);
    }
    else
    {
        texID = tex;
    }

    glBindTexture(GL_TEXTURE_2D, texID);
    if (tex == -1)
        glTexImage2D(GL_TEXTURE_2D, 0, internal_format, width, height, 0, GL_RGBA,
                     internal_format == GL_RGBA32F ? GL_FLOAT : GL_UNSIGNED_BYTE, 0);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glBindTexture(GL_TEXTURE_2D, 0);

    // Create a renderbuffer object to store depth info
//     glGenRenderbuffers(1, &rboID);
//     glBindRenderbuffer(GL_RENDERBUFFER, rboID);
//     glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, width, height);
//     glBindRenderbuffer(GL_RENDERBUFFER, 0);

    GLint oldFboID;
    glGetIntegerv(GL_DRAW_FRAMEBUFFER_BINDING, &oldFboID);

    // Create a framebuffer object
    glGenFramebuffers(1, &fboID);
    glBindFramebuffer(GL_FRAMEBUFFER, fboID);
    //LOG("RTT CREATE %d - tex %d", fboID, texID);

    // Attach the texture to FBO color attachment point
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texID, 0);

    // Attach the renderbuffer to depth attachment point
    //glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, rboID);

    auto err2str = [](GLenum err) {
        switch (err)
        {
        case GL_FRAMEBUFFER_UNDEFINED: return "GL_FRAMEBUFFER_UNDEFINED";
        case GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT: return "GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT";
        case GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT: return "GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT";
        case GL_FRAMEBUFFER_UNSUPPORTED: return "GL_FRAMEBUFFER_UNSUPPORTED";
        case GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE: return "GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE";
        default: return "UNKNOWN";
        }
    };

    // Check FBO status
    GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
    if (status != GL_FRAMEBUFFER_COMPLETE)
        LOG("RTT::create failed because: %s", err2str(status));

    // Switch back to window-system-provided framebuffer
    glBindFramebuffer(GL_FRAMEBUFFER, oldFboID);
    oldRFboID = 0;
    oldDFboID = 0;

    return status == GL_FRAMEBUFFER_COMPLETE;
}

void RTT::bindFramebuffer()
{
#ifdef DEBUG
    if (bound)
    {
        LOG("framebuffer bound twice!");
#ifdef _WIN32
        __debugbreak();
#endif
    }
#endif // _DEBUG
    bound = true;
    glGetIntegerv(GL_DRAW_FRAMEBUFFER_BINDING, &oldDFboID);
    glGetIntegerv(GL_READ_FRAMEBUFFER_BINDING, &oldRFboID);
    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, fboID);
    glBindFramebuffer(GL_READ_FRAMEBUFFER, fboID);
}

void RTT::unbindFramebuffer()
{
    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, oldDFboID);
    glBindFramebuffer(GL_READ_FRAMEBUFFER, oldRFboID);
    oldRFboID = 0;
    oldDFboID = 0;
    bound = false;
}

void RTT::clear(glm::vec4 color)
{
    glClearColor(color.r, color.g, color.b, color.a);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
}

void RTT::readTextureData(uint8_t* buffer)
{
    glReadBuffer(GL_BACK);
    bindFramebuffer();
    //glGetTexImage(GL_TEXTURE_2D, 0, GL_RGB, GL_UNSIGNED_BYTE, buffer);
    glReadPixels(0, 0, w, h, GL_RGBA, GL_UNSIGNED_BYTE, buffer);
    unbindFramebuffer();
    //glReadBuffer(GL_NONE);
}

uint8_t* RTT::createBuffer()
{
    return new uint8_t[w * h * 4];
}

void RTT::bindTexture()
{
    glBindTexture(GL_TEXTURE_2D, texID);
}

void RTT::unbindTexture()
{
    glBindTexture(GL_TEXTURE_2D, 0);
}