CFBORender.cpp

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2020, Individual contributors, see AUTHORS file     |
   | See: https://www.mrpt.org/Authors - All rights reserved.               |
   | Released under BSD License. See: https://www.mrpt.org/License          |
   +------------------------------------------------------------------------+ */

#include "opengl-precomp.h"  // Precompiled header

#include <mrpt/opengl/CFBORender.h>
#include <mrpt/opengl/opengl_api.h>

using namespace std;
using namespace mrpt;
using namespace mrpt::opengl;
using mrpt::img::CImage;

/*---------------------------------------------------------------
                        Constructor
---------------------------------------------------------------*/
CFBORender::CFBORender(
    unsigned int width, unsigned int height, const bool skip_glut_window)
    : m_width(width),
      m_height(height),
      m_win_used(!skip_glut_window),
      m_default_bk_color(.6f, .6f, .6f, 1)
{
#if MRPT_HAS_OPENCV && MRPT_HAS_OPENGL_GLUT

    MRPT_START

    if (m_win_used)
    {
        // check a previous initialization of the GLUT
        if (!glutGet(GLUT_INIT_STATE))
        {
            // create the context (a little trick)
            int argc = 1;
            char* argv[1] = {nullptr};
            glutInit(&argc, argv);
        }

        // create a hidden window
        m_win = glutCreateWindow("CFBORender");
        glutHideWindow();
    }

    // call after creating the hidden window
    if (!isExtensionSupported("GL_EXT_framebuffer_object"))
        THROW_EXCEPTION("Framebuffer Object extension unsupported");

// In win32 we have to load the pointers to the functions:
#ifdef _WIN32
    glGenFramebuffersEXT =
        (PFNGLGENFRAMEBUFFERSEXTPROC)wglGetProcAddress("glGenFramebuffersEXT");
    glDeleteFramebuffersEXT = (PFNGLDELETEFRAMEBUFFERSEXTPROC)wglGetProcAddress(
        "glDeleteFramebuffersEXT");
    glBindFramebufferEXT =
        (PFNGLBINDFRAMEBUFFEREXTPROC)wglGetProcAddress("glBindFramebufferEXT");
    glFramebufferTexture2DEXT =
        (PFNGLFRAMEBUFFERTEXTURE2DEXTPROC)wglGetProcAddress(
            "glFramebufferTexture2DEXT");

    ASSERT_(glGenFramebuffersEXT != nullptr);
    ASSERT_(glDeleteFramebuffersEXT != nullptr);
    ASSERT_(glBindFramebufferEXT != nullptr);
    ASSERT_(glFramebufferTexture2DEXT != nullptr);
#endif

    // gen the frambuffer object (FBO), similar manner as a texture
    glGenFramebuffersEXT(1, &m_fbo);

    // bind the framebuffer, fbo, so operations will now occur on it
    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, m_fbo);

    // change viewport size (in pixels)
    glViewport(0, 0, m_width, m_height);

    // make a texture
    glGenTextures(1, &m_tex);

    // initialize texture that will store the framebuffer image
    const GLenum texTarget =
#if defined(GL_TEXTURE_RECTANGLE_NV)
        GL_TEXTURE_RECTANGLE_NV;
#elif defined(GL_TEXTURE_RECTANGLE_ARB)
        GL_TEXTURE_RECTANGLE_ARB;
#else
        GL_TEXTURE_RECTANGLE_EXT;
#endif

    glBindTexture(texTarget, m_tex);
    glTexImage2D(
        texTarget, 0, GL_RGB, m_width, m_height, 0, GL_RGB, GL_UNSIGNED_BYTE,
        nullptr);

    // bind this texture to the current framebuffer obj. as color_attachement_0
    glFramebufferTexture2DEXT(
        GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, texTarget, m_tex, 0);

    //'unbind' the frambuffer object, so subsequent drawing ops are not drawn
    // into the FBO.
    // '0' means "windowing system provided framebuffer
    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

    MRPT_END

//#else
//  THROW_EXCEPTION("MRPT compiled without OpenCV and/or OpenGL support!!");
#endif
}

/*---------------------------------------------------------------
                        Destructor:
 ---------------------------------------------------------------*/
CFBORender::~CFBORender()
{
#if MRPT_HAS_OPENGL_GLUT
    // delete the current texture, the framebuffer object and the GLUT window
    glDeleteTextures(1, &m_tex);
    glDeleteFramebuffersEXT(1, &m_fbo);
    if (m_win_used) glutDestroyWindow(m_win);
#endif
}

/*---------------------------------------------------------------
                    Set the scene camera
 ---------------------------------------------------------------*/
void CFBORender::setCamera(const COpenGLScene& scene, const CCamera& camera)
{
    MRPT_START

    scene.getViewport("main")->getCamera() = camera;

    MRPT_END
}

/*---------------------------------------------------------------
                    Get the scene camera
 ---------------------------------------------------------------*/
CCamera& CFBORender::getCamera(const COpenGLScene& scene)
{
    MRPT_START

    return scene.getViewport("main")->getCamera();

    MRPT_END
}

/*---------------------------------------------------------------
        Render the scene and get the rendered rgb image. This
        function resizes the image buffer if it is necessary
 ---------------------------------------------------------------*/
void CFBORender::getFrame(
    [[maybe_unused]] const COpenGLScene& scene, [[maybe_unused]] CImage& buffer)
{
#if MRPT_HAS_OPENCV && MRPT_HAS_OPENGL_GLUT

    MRPT_START

    // resize the buffer if it is necessary
    if (buffer.getWidth() != static_cast<size_t>(m_width) ||
        buffer.getHeight() != static_cast<size_t>(m_height) ||
        buffer.getChannelCount() != 3 || buffer.isOriginTopLeft() != false)
    {
        buffer.resize(m_width, m_height, mrpt::img::CH_RGB);
    }

    // Go on.
    getFrame2(scene, buffer);
    ;

    MRPT_END
#endif
}

/*---------------------------------------------------------------
        Render the scene and get the rendered rgb image. This
        function does not resize the image buffer.
 ---------------------------------------------------------------*/
void CFBORender::getFrame2(
    [[maybe_unused]] const COpenGLScene& scene, [[maybe_unused]] CImage& buffer)
{
#if MRPT_HAS_OPENGL_GLUT

    MRPT_START

    // check the buffer size
    ASSERT_EQUAL_(buffer.getWidth(), static_cast<size_t>(m_width));
    ASSERT_EQUAL_(buffer.getHeight(), static_cast<size_t>(m_height));
    ASSERT_EQUAL_(buffer.getChannelCount(), 3);
    ASSERT_EQUAL_(buffer.isOriginTopLeft(), false);
    // bind the framebuffer, fbo, so operations will now occur on it
    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, m_fbo);

    glClearColor(
        m_default_bk_color.R, m_default_bk_color.G, m_default_bk_color.B,
        m_default_bk_color.A);

    // Render opengl objects:
    // ---------------------------
    scene.render();

    // TODO NOTE: This should fail if the image has padding bytes. See
    // glPixelStore() etc.
    glReadPixels(
        0, 0, m_width, m_height, GL_BGR_EXT, GL_UNSIGNED_BYTE, buffer(0, 0));

    //'unbind' the frambuffer object, so subsequent drawing ops are not drawn
    // into the FBO.
    // '0' means "windowing system provided framebuffer
    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

    MRPT_END
#endif
}

/*---------------------------------------------------------------
                    Resize the image size
 ---------------------------------------------------------------*/
void CFBORender::resize(
    [[maybe_unused]] unsigned int width, [[maybe_unused]] unsigned int height)
{
#if MRPT_HAS_OPENCV && MRPT_HAS_OPENGL_GLUT

    MRPT_START

    // update members
    m_width = width;
    m_height = height;

    // bind the framebuffer, fbo, so operations will now occur on it
    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, m_fbo);

    // change viewport size (in pixels)
    glViewport(0, 0, m_width, m_height);

    // change texture size
    const GLenum texTarget =
#if defined(GL_TEXTURE_RECTANGLE_NV)
        GL_TEXTURE_RECTANGLE_NV;
#elif defined(GL_TEXTURE_RECTANGLE_ARB)
        GL_TEXTURE_RECTANGLE_ARB;
#else
        GL_TEXTURE_RECTANGLE_EXT;
#endif

    glBindTexture(texTarget, m_tex);
    glTexImage2D(
        texTarget, 0, GL_RGB, m_width, m_height, 0, GL_RGB, GL_UNSIGNED_BYTE,
        nullptr);

    //'unbind' the frambuffer object, so subsequent drawing ops are not drawn
    // into the FBO.
    // '0' means "windowing system provided framebuffer
    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

    MRPT_END

//#else
//  THROW_EXCEPTION("MRPT compiled without OpenCV and/or OpenGL support!!");
#endif
}

/*---------------------------------------------------------------
        Provide information on Framebuffer object extension
 ---------------------------------------------------------------*/
int CFBORender::isExtensionSupported([[maybe_unused]] const char* extension)
{
#if MRPT_HAS_OPENGL_GLUT

    MRPT_START

    /* Extension names should not have spaces. */
    auto where = strchr(extension, ' ');
    if (where || *extension == '\0') return 0;
    const auto extensions = glGetString(GL_EXTENSIONS);

    /* It takes a bit of care to be fool-proof about parsing the
    OpenGL extensions string. Don't be fooled by sub-strings,
    etc. */
    auto start = reinterpret_cast<const char*>(extensions);
    for (;;)
    {
        where = strstr(start, extension);
        if (!where) break;
        auto terminator = where + strlen(extension);
        if (where == start || *(where - 1) == ' ')
            if (*terminator == ' ' || *terminator == '\0') return 1;
        start = terminator;
    }

    MRPT_END
#endif

    return 0;
}