JUCE/modules/juce_opengl/opengl/juce_OpenGLFrameBuffer.cpp

/*
  ==============================================================================

   This file is part of the JUCE library.
   Copyright (c) 2013 - Raw Material Software Ltd.

   Permission is granted to use this software under the terms of either:
   a) the GPL v2 (or any later version)
   b) the Affero GPL v3

   Details of these licenses can be found at: www.gnu.org/licenses

   JUCE is distributed in the hope that it will be useful, but WITHOUT ANY
   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
   A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

   ------------------------------------------------------------------------------

   To release a closed-source product which uses JUCE, commercial licenses are
   available: visit www.juce.com for more information.

  ==============================================================================
*/

class OpenGLFrameBuffer::Pimpl
{
public:
    Pimpl (OpenGLContext& c, const int w, const int h,
           const bool wantsDepthBuffer, const bool wantsStencilBuffer)
        : context (c), width (w), height (h),
          textureID (0), frameBufferID (0), depthOrStencilBuffer (0),
          hasDepthBuffer (false), hasStencilBuffer (false)
    {
        // Framebuffer objects can only be created when the current thread has an active OpenGL
        // context. You'll need to create this object in one of the OpenGLContext's callbacks.
        jassert (OpenGLHelpers::isContextActive());

       #if JUCE_WINDOWS || JUCE_LINUX
        if (context.extensions.glGenFramebuffers == nullptr)
            return;
       #endif

        context.extensions.glGenFramebuffers (1, &frameBufferID);
        context.extensions.glBindFramebuffer (GL_FRAMEBUFFER, frameBufferID);
        JUCE_CHECK_OPENGL_ERROR

        glGenTextures (1, &textureID);
        glBindTexture (GL_TEXTURE_2D, textureID);
        JUCE_CHECK_OPENGL_ERROR

        glTexParameterf (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
        glTexParameterf (GL_TEXTURE_2D, GL_TEXTURE_MAG_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);

        glTexImage2D (GL_TEXTURE_2D, 0, GL_RGBA8, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
        JUCE_CHECK_OPENGL_ERROR

        context.extensions.glFramebufferTexture2D (GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, textureID, 0);

        if (wantsDepthBuffer || wantsStencilBuffer)
        {
            context.extensions.glGenRenderbuffers (1, &depthOrStencilBuffer);
            context.extensions.glBindRenderbuffer (GL_RENDERBUFFER, depthOrStencilBuffer);
            jassert (context.extensions.glIsRenderbuffer (depthOrStencilBuffer));

            context.extensions.glRenderbufferStorage (GL_RENDERBUFFER,
                                      (wantsDepthBuffer && wantsStencilBuffer) ? GL_DEPTH24_STENCIL8
                                                                              #if JUCE_OPENGL_ES
                                                                               : GL_DEPTH_COMPONENT16,
                                                                              #else
                                                                               : GL_DEPTH_COMPONENT,
                                                                              #endif
                                      width, height);

            GLint params = 0;
            context.extensions.glGetRenderbufferParameteriv (GL_RENDERBUFFER, GL_RENDERBUFFER_DEPTH_SIZE, &params);
            context.extensions.glFramebufferRenderbuffer (GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthOrStencilBuffer);

            if (wantsStencilBuffer)
                context.extensions.glFramebufferRenderbuffer (GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, depthOrStencilBuffer);

            hasDepthBuffer = wantsDepthBuffer;
            hasStencilBuffer = wantsStencilBuffer;
        }

        context.extensions.glBindFramebuffer (GL_FRAMEBUFFER, 0);
    }

    ~Pimpl()
    {
        if (OpenGLHelpers::isContextActive())
        {
            if (textureID != 0)
                glDeleteTextures (1, &textureID);

            if (depthOrStencilBuffer != 0)
                context.extensions.glDeleteRenderbuffers (1, &depthOrStencilBuffer);

            if (frameBufferID != 0)
                context.extensions.glDeleteFramebuffers (1, &frameBufferID);

            JUCE_CHECK_OPENGL_ERROR
        }
    }

    bool createdOk() const
    {
        return frameBufferID != 0 && textureID != 0;
    }

    void bind()
    {
        context.extensions.glBindFramebuffer (GL_FRAMEBUFFER, frameBufferID);
        JUCE_CHECK_OPENGL_ERROR
    }

    void unbind()
    {
        context.extensions.glBindFramebuffer (GL_FRAMEBUFFER, 0);
        JUCE_CHECK_OPENGL_ERROR
    }

    OpenGLContext& context;
    const int width, height;
    GLuint textureID, frameBufferID, depthOrStencilBuffer;
    bool hasDepthBuffer, hasStencilBuffer;

private:
    bool checkStatus() noexcept
    {
        const GLenum status = context.extensions.glCheckFramebufferStatus (GL_FRAMEBUFFER);

        return status == GL_NO_ERROR
            || status == GL_FRAMEBUFFER_COMPLETE;
    }

    JUCE_DECLARE_NON_COPYABLE (Pimpl)
};

//==============================================================================
class OpenGLFrameBuffer::SavedState
{
public:
    SavedState (OpenGLFrameBuffer& buffer, const int w, const int h)
        : width (w), height (h),
          data ((size_t) (w * h))
    {
        buffer.readPixels (data, Rectangle<int> (w, h));
    }

    bool restore (OpenGLContext& context, OpenGLFrameBuffer& buffer)
    {
        if (buffer.initialise (context, width, height))
        {
            buffer.writePixels (data, Rectangle<int> (width, height));
            return true;
        }

        return false;
    }

private:
    const int width, height;
    HeapBlock <PixelARGB> data;

    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (SavedState)
};

//==============================================================================
OpenGLFrameBuffer::OpenGLFrameBuffer() {}
OpenGLFrameBuffer::~OpenGLFrameBuffer() {}

bool OpenGLFrameBuffer::initialise (OpenGLContext& context, int width, int height)
{
    jassert (context.isActive()); // The context must be active when creating a framebuffer!

    pimpl = nullptr;
    pimpl = new Pimpl (context, width, height, false, false);

    if (! pimpl->createdOk())
        pimpl = nullptr;

    return pimpl != nullptr;
}

bool OpenGLFrameBuffer::initialise (OpenGLContext& context, const Image& image)
{
    if (! image.isARGB())
        return initialise (context, image.convertedToFormat (Image::ARGB));

    Image::BitmapData bitmap (image, Image::BitmapData::readOnly);

    return initialise (context, bitmap.width, bitmap.height)
            && writePixels ((const PixelARGB*) bitmap.data, image.getBounds());
}

bool OpenGLFrameBuffer::initialise (OpenGLFrameBuffer& other)
{
    const Pimpl* const p = other.pimpl;

    if (p == nullptr)
    {
        pimpl = nullptr;
        return true;
    }

    const Rectangle<int> area (pimpl->width, pimpl->height);

    if (initialise (p->context, area.getWidth(), area.getHeight()))
    {
        pimpl->bind();

       #if ! JUCE_ANDROID
        glEnable (GL_TEXTURE_2D);
        clearGLError();
       #endif
        glBindTexture (GL_TEXTURE_2D, p->textureID);
        pimpl->context.copyTexture (area, area, area.getWidth(), area.getHeight(), false);
        glBindTexture (GL_TEXTURE_2D, 0);
        JUCE_CHECK_OPENGL_ERROR

        pimpl->unbind();
        return true;
    }

    return false;
}

void OpenGLFrameBuffer::release()
{
    pimpl = nullptr;
    savedState = nullptr;
}

void OpenGLFrameBuffer::saveAndRelease()
{
    if (pimpl != nullptr)
    {
        savedState = new SavedState (*this, pimpl->width, pimpl->height);
        pimpl = nullptr;
    }
}

bool OpenGLFrameBuffer::reloadSavedCopy (OpenGLContext& context)
{
    if (savedState != nullptr)
    {
        ScopedPointer<SavedState> state (savedState);

        if (state->restore (context, *this))
            return true;

        savedState = state;
    }

    return false;
}

int OpenGLFrameBuffer::getWidth() const noexcept            { return pimpl != nullptr ? pimpl->width : 0; }
int OpenGLFrameBuffer::getHeight() const noexcept           { return pimpl != nullptr ? pimpl->height : 0; }
GLuint OpenGLFrameBuffer::getTextureID() const noexcept     { return pimpl != nullptr ? pimpl->textureID : 0; }

bool OpenGLFrameBuffer::makeCurrentRenderingTarget()
{
    // trying to use a framebuffer after saving it with saveAndRelease()! Be sure to call
    // reloadSavedCopy() to put it back into GPU memory before using it..
    jassert (savedState == nullptr);

    if (pimpl == nullptr)
        return false;

    pimpl->bind();
    return true;
}

GLuint OpenGLFrameBuffer::getFrameBufferID() const
{
    return pimpl != nullptr ? pimpl->frameBufferID : 0;
}

GLuint OpenGLFrameBuffer::getCurrentFrameBufferTarget()
{
    GLint fb;
    glGetIntegerv (GL_FRAMEBUFFER_BINDING, &fb);
    return (GLuint) fb;
}

void OpenGLFrameBuffer::releaseAsRenderingTarget()
{
    if (pimpl != nullptr)
        pimpl->context.extensions.glBindFramebuffer (GL_FRAMEBUFFER, 0);
}

void OpenGLFrameBuffer::clear (Colour colour)
{
    if (makeCurrentRenderingTarget())
    {
        OpenGLHelpers::clear (colour);
        releaseAsRenderingTarget();
    }
}

void OpenGLFrameBuffer::makeCurrentAndClear()
{
    if (makeCurrentRenderingTarget())
    {
        glClearColor (0, 0, 0, 0);
        glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
    }
}

bool OpenGLFrameBuffer::readPixels (PixelARGB* target, const Rectangle<int>& area)
{
    if (! makeCurrentRenderingTarget())
        return false;

    glPixelStorei (GL_PACK_ALIGNMENT, 4);
    glReadPixels (area.getX(), area.getY(), area.getWidth(), area.getHeight(),
                  JUCE_RGBA_FORMAT, GL_UNSIGNED_BYTE, target);
    pimpl->context.extensions.glBindFramebuffer (GL_FRAMEBUFFER, 0);
    JUCE_CHECK_OPENGL_ERROR
    return true;
}

bool OpenGLFrameBuffer::writePixels (const PixelARGB* data, const Rectangle<int>& area)
{
    OpenGLTargetSaver ts (pimpl->context);

    if (! makeCurrentRenderingTarget())
        return false;

    glDisable (GL_DEPTH_TEST);
    glDisable (GL_BLEND);
    JUCE_CHECK_OPENGL_ERROR

   #if JUCE_OPENGL_ES && JUCE_USE_OPENGL_FIXED_FUNCTION
    OpenGLTexture tex;
    tex.loadARGBFlipped (data, area.getWidth(), area.getHeight());

    const int texH = tex.getHeight();
    tex.bind();
    const GLint cropRect[4] = { 0, texH - area.getHeight(), area.getWidth(), area.getHeight() };
    glTexParameteriv (GL_TEXTURE_2D, GL_TEXTURE_CROP_RECT_OES, cropRect);
    glEnable (GL_TEXTURE_2D);
    clearGLError();
    glColor4f (1.0f, 1.0f, 1.0f, 1.0f);
    glDrawTexiOES (area.getX(), area.getY(), 1, area.getWidth(), area.getHeight());
    glBindTexture (GL_TEXTURE_2D, 0);
   #else
    OpenGLTexture tex;
    tex.loadARGB (data, area.getWidth(), area.getHeight());

    glViewport (0, 0, pimpl->width, pimpl->height);
    pimpl->context.copyTexture (area, Rectangle<int> (area.getX(), area.getY(),
                                                      tex.getWidth(), tex.getHeight()),
                                pimpl->width, pimpl->height, true);
   #endif

    JUCE_CHECK_OPENGL_ERROR
    return true;
}

#if JUCE_USE_OPENGL_FIXED_FUNCTION
void OpenGLFrameBuffer::draw2D (float x1, float y1,
                                float x2, float y2,
                                float x3, float y3,
                                float x4, float y4,
                                Colour colour) const
{
    if (pimpl != nullptr)
    {
        glBindTexture (GL_TEXTURE_2D, pimpl->textureID);
        OpenGLHelpers::drawQuad2D (x1, y1, x2, y2, x3, y3, x4, y4, colour);
        glBindTexture (GL_TEXTURE_2D, 0);
    }
}

void OpenGLFrameBuffer::draw3D (float x1, float y1, float z1,
                                float x2, float y2, float z2,
                                float x3, float y3, float z3,
                                float x4, float y4, float z4,
                                Colour colour) const
{
    if (pimpl != nullptr)
    {
        glBindTexture (GL_TEXTURE_2D, pimpl->textureID);
        OpenGLHelpers::drawQuad3D (x1, y1, z1, x2, y2, z2, x3, y3, z3, x4, y4, z4, colour);
        glBindTexture (GL_TEXTURE_2D, 0);
    }
}

void OpenGLFrameBuffer::drawAt (float x1, float y1) const
{
    if (pimpl != nullptr)
    {
       #if ! JUCE_ANDROID
        glEnable (GL_TEXTURE_2D);
        clearGLError();
       #endif
        glBindTexture (GL_TEXTURE_2D, pimpl->textureID);

        glDisableClientState (GL_COLOR_ARRAY);
        glDisableClientState (GL_NORMAL_ARRAY);

        const GLfloat vertices[] = { x1, y1,
                                     x1 + pimpl->width, y1,
                                     x1, y1 + pimpl->height,
                                     x1 + pimpl->width, y1 + pimpl->height };

        const GLfloat textureCoords[] = { 0, 0, 1.0f, 0, 0, 1.0f, 1.0f, 1.0f };

        glEnableClientState (GL_VERTEX_ARRAY);
        glVertexPointer (2, GL_FLOAT, 0, vertices);

        glEnableClientState (GL_TEXTURE_COORD_ARRAY);
        glTexCoordPointer (2, GL_FLOAT, 0, textureCoords);

        glDrawArrays (GL_TRIANGLE_STRIP, 0, 4);
        glBindTexture (GL_TEXTURE_2D, 0);
    }
}
#endif