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kc3-lang/angle/src/libGLESv2/Framebuffer.cpp

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  • Author : Geoff Lang
    Date : 2013-10-16 14:12:50
    Hash : 005df41f
    Message : Use GLenum instead of GLint to store internal format variables. TRAC #23785 Signed-off-by: Jamie Madill Signed-off-by: Shannon Woods

  • src/libGLESv2/Framebuffer.cpp
  • #include "precompiled.h"
    //
    // Copyright (c) 2002-2013 The ANGLE Project Authors. All rights reserved.
    // Use of this source code is governed by a BSD-style license that can be
    // found in the LICENSE file.
    //
    
    // Framebuffer.cpp: Implements the gl::Framebuffer class. Implements GL framebuffer
    // objects and related functionality. [OpenGL ES 2.0.24] section 4.4 page 105.
    
    #include "libGLESv2/Framebuffer.h"
    
    #include "libGLESv2/main.h"
    #include "common/utilities.h"
    #include "libGLESv2/formatutils.h"
    #include "libGLESv2/Texture.h"
    #include "libGLESv2/Context.h"
    #include "libGLESv2/renderer/Renderer.h"
    #include "libGLESv2/Renderbuffer.h"
    
    namespace gl
    {
    
    Framebuffer::Framebuffer(rx::Renderer *renderer)
        : mRenderer(renderer)
    {
        for (unsigned int colorAttachment = 0; colorAttachment < IMPLEMENTATION_MAX_DRAW_BUFFERS; colorAttachment++)
        {
            mDrawBufferStates[colorAttachment] = GL_NONE;
        }
        mDrawBufferStates[0] = GL_COLOR_ATTACHMENT0_EXT;
        mReadBufferState = GL_COLOR_ATTACHMENT0_EXT;
    }
    
    Framebuffer::~Framebuffer()
    {
        for (unsigned int colorAttachment = 0; colorAttachment < IMPLEMENTATION_MAX_DRAW_BUFFERS; colorAttachment++)
        {
            mColorbuffers[colorAttachment].set(NULL, GL_NONE, 0, 0);
        }
        mDepthbuffer.set(NULL, GL_NONE, 0, 0);
        mStencilbuffer.set(NULL, GL_NONE, 0, 0);
    }
    
    Renderbuffer *Framebuffer::lookupRenderbuffer(GLenum type, GLuint handle, GLint level, GLint layer) const
    {
        gl::Context *context = gl::getContext();
    
        switch (type)
        {
          case GL_NONE:
            return NULL;
    
          case GL_RENDERBUFFER:
            return context->getRenderbuffer(handle);
    
          case GL_TEXTURE_2D:
            {
                Texture *texture = context->getTexture(handle);
                if (texture && texture->getTarget() == GL_TEXTURE_2D)
                {
                    return static_cast<Texture2D*>(texture)->getRenderbuffer(level);
                }
                else
                {
                    return NULL;
                }
            }
    
          case GL_TEXTURE_CUBE_MAP_POSITIVE_X:
          case GL_TEXTURE_CUBE_MAP_NEGATIVE_X:
          case GL_TEXTURE_CUBE_MAP_POSITIVE_Y:
          case GL_TEXTURE_CUBE_MAP_NEGATIVE_Y:
          case GL_TEXTURE_CUBE_MAP_POSITIVE_Z:
          case GL_TEXTURE_CUBE_MAP_NEGATIVE_Z:
            {
                Texture *texture = context->getTexture(handle);
                if (texture && texture->getTarget() == GL_TEXTURE_CUBE_MAP)
                {
                    return static_cast<TextureCubeMap*>(texture)->getRenderbuffer(type, level);
                }
                else
                {
                    return NULL;
                }
            }
    
          case GL_TEXTURE_3D:
            {
                Texture *texture = context->getTexture(handle);
                if (texture && texture->getTarget() == GL_TEXTURE_3D)
                {
                    return static_cast<Texture3D*>(texture)->getRenderbuffer(level, layer);
                }
                else
                {
                    return NULL;
                }
            }
    
          case GL_TEXTURE_2D_ARRAY:
            {
                Texture *texture = context->getTexture(handle);
                if (texture && texture->getTarget() == GL_TEXTURE_2D_ARRAY)
                {
                    return static_cast<Texture2DArray*>(texture)->getRenderbuffer(level, layer);
                }
                else
                {
                    return NULL;
                }
            }
    
          default:
            UNREACHABLE();
            return NULL;
        }
    }
    
    void Framebuffer::setColorbuffer(unsigned int colorAttachment, GLenum type, GLuint colorbuffer, GLint level, GLint layer)
    {
        ASSERT(colorAttachment < IMPLEMENTATION_MAX_DRAW_BUFFERS);
        Renderbuffer *renderBuffer = lookupRenderbuffer(type, colorbuffer, level, layer);
        if (renderBuffer)
        {
            mColorbuffers[colorAttachment].set(renderBuffer, type, level, layer);
        }
        else
        {
            mColorbuffers[colorAttachment].set(NULL, GL_NONE, 0, 0);
        }
    }
    
    void Framebuffer::setDepthbuffer(GLenum type, GLuint depthbuffer, GLint level, GLint layer)
    {
        Renderbuffer *renderBuffer = lookupRenderbuffer(type, depthbuffer, level, layer);
        if (renderBuffer)
        {
            mDepthbuffer.set(renderBuffer, type, level, layer);
        }
        else
        {
            mDepthbuffer.set(NULL, GL_NONE, 0, 0);
        }
    }
    
    void Framebuffer::setStencilbuffer(GLenum type, GLuint stencilbuffer, GLint level, GLint layer)
    {
        Renderbuffer *renderBuffer = lookupRenderbuffer(type, stencilbuffer, level, layer);
        if (renderBuffer)
        {
            mStencilbuffer.set(renderBuffer, type, level, layer);
        }
        else
        {
            mStencilbuffer.set(NULL, GL_NONE, 0, 0);
        }
    }
    
    void Framebuffer::setDepthStencilBuffer(GLenum type, GLuint depthStencilBuffer, GLint level, GLint layer)
    {
        Renderbuffer *renderBuffer = lookupRenderbuffer(type, depthStencilBuffer, level, layer);
        if (renderBuffer && renderBuffer->getDepthSize() > 0 && renderBuffer->getStencilSize() > 0)
        {
            mDepthbuffer.set(renderBuffer, type, level, layer);
            mStencilbuffer.set(renderBuffer, type, level, layer);
        }
        else
        {
            mDepthbuffer.set(NULL, GL_NONE, 0, 0);
            mStencilbuffer.set(NULL, GL_NONE, 0, 0);
        }
    }
    
    void Framebuffer::detachTexture(GLuint texture)
    {
        for (unsigned int colorAttachment = 0; colorAttachment < IMPLEMENTATION_MAX_DRAW_BUFFERS; colorAttachment++)
        {
            if (mColorbuffers[colorAttachment].id() == texture &&
                IsInternalTextureTarget(mColorbuffers[colorAttachment].type(), mRenderer->getCurrentClientVersion()))
            {
                mColorbuffers[colorAttachment].set(NULL, GL_NONE, 0, 0);
            }
        }
    
        if (mDepthbuffer.id() == texture && IsInternalTextureTarget(mDepthbuffer.type(), mRenderer->getCurrentClientVersion()))
        {
            mDepthbuffer.set(NULL, GL_NONE, 0, 0);
        }
    
        if (mStencilbuffer.id() == texture && IsInternalTextureTarget(mStencilbuffer.type(), mRenderer->getCurrentClientVersion()))
        {
            mStencilbuffer.set(NULL, GL_NONE, 0, 0);
        }
    }
    
    void Framebuffer::detachRenderbuffer(GLuint renderbuffer)
    {
        for (unsigned int colorAttachment = 0; colorAttachment < IMPLEMENTATION_MAX_DRAW_BUFFERS; colorAttachment++)
        {
            if (mColorbuffers[colorAttachment].id() == renderbuffer && mColorbuffers[colorAttachment].type() == GL_RENDERBUFFER)
            {
                mColorbuffers[colorAttachment].set(NULL, GL_NONE, 0, 0);
            }
        }
    
        if (mDepthbuffer.id() == renderbuffer && mDepthbuffer.type() == GL_RENDERBUFFER)
        {
            mDepthbuffer.set(NULL, GL_NONE, 0, 0);
        }
    
        if (mStencilbuffer.id() == renderbuffer && mStencilbuffer.type() == GL_RENDERBUFFER)
        {
            mStencilbuffer.set(NULL, GL_NONE, 0, 0);
        }
    }
    
    unsigned int Framebuffer::getRenderTargetSerial(unsigned int colorAttachment) const
    {
        ASSERT(colorAttachment < IMPLEMENTATION_MAX_DRAW_BUFFERS);
    
        Renderbuffer *colorbuffer = mColorbuffers[colorAttachment].get();
    
        if (colorbuffer)
        {
            return colorbuffer->getSerial();
        }
    
        return 0;
    }
    
    unsigned int Framebuffer::getDepthbufferSerial() const
    {
        Renderbuffer *depthbuffer = mDepthbuffer.get();
    
        if (depthbuffer)
        {
            return depthbuffer->getSerial();
        }
    
        return 0;
    }
    
    unsigned int Framebuffer::getStencilbufferSerial() const
    {
        Renderbuffer *stencilbuffer = mStencilbuffer.get();
    
        if (stencilbuffer)
        {
            return stencilbuffer->getSerial();
        }
    
        return 0;
    }
    
    Renderbuffer *Framebuffer::getColorbuffer(unsigned int colorAttachment) const
    {
        ASSERT(colorAttachment < IMPLEMENTATION_MAX_DRAW_BUFFERS);
        return mColorbuffers[colorAttachment].get();
    }
    
    Renderbuffer *Framebuffer::getDepthbuffer() const
    {
        return mDepthbuffer.get();
    }
    
    Renderbuffer *Framebuffer::getStencilbuffer() const
    {
        return mStencilbuffer.get();
    }
    
    Renderbuffer *Framebuffer::getDepthStencilBuffer() const
    {
        return (mDepthbuffer.id() == mStencilbuffer.id()) ? mDepthbuffer.get() : NULL;
    }
    
    Renderbuffer *Framebuffer::getDepthOrStencilbuffer() const
    {
        Renderbuffer *depthstencilbuffer = mDepthbuffer.get();
        
        if (!depthstencilbuffer)
        {
            depthstencilbuffer = mStencilbuffer.get();
        }
    
        return depthstencilbuffer;
    }
    
    Renderbuffer *Framebuffer::getReadColorbuffer() const
    {
        // Will require more logic if glReadBuffers is supported
        return mColorbuffers[0].get();
    }
    
    GLenum Framebuffer::getReadColorbufferType() const
    {
        // Will require more logic if glReadBuffers is supported
        return mColorbuffers[0].type();
    }
    
    Renderbuffer *Framebuffer::getFirstColorbuffer() const
    {
        for (unsigned int colorAttachment = 0; colorAttachment < IMPLEMENTATION_MAX_DRAW_BUFFERS; colorAttachment++)
        {
            if (mColorbuffers[colorAttachment].type() != GL_NONE)
            {
                return mColorbuffers[colorAttachment].get();
            }
        }
    
        return NULL;
    }
    
    GLenum Framebuffer::getColorbufferType(unsigned int colorAttachment) const
    {
        ASSERT(colorAttachment < IMPLEMENTATION_MAX_DRAW_BUFFERS);
        return mColorbuffers[colorAttachment].type();
    }
    
    GLenum Framebuffer::getDepthbufferType() const
    {
        return mDepthbuffer.type();
    }
    
    GLenum Framebuffer::getStencilbufferType() const
    {
        return mStencilbuffer.type();
    }
    
    GLenum Framebuffer::getDepthStencilbufferType() const
    {
        return (mDepthbuffer.id() == mStencilbuffer.id()) ? mDepthbuffer.type() : GL_NONE;
    }
    
    GLuint Framebuffer::getColorbufferHandle(unsigned int colorAttachment) const
    {
        ASSERT(colorAttachment < IMPLEMENTATION_MAX_DRAW_BUFFERS);
        return mColorbuffers[colorAttachment].id();
    }
    
    GLuint Framebuffer::getDepthbufferHandle() const
    {
        return mDepthbuffer.id();
    }
    
    GLuint Framebuffer::getStencilbufferHandle() const
    {
        return mStencilbuffer.id();
    }
    
    GLenum Framebuffer::getDepthStencilbufferHandle() const
    {
        return (mDepthbuffer.id() == mStencilbuffer.id()) ? mDepthbuffer.id() : 0;
    }
    
    GLenum Framebuffer::getColorbufferMipLevel(unsigned int colorAttachment) const
    {
        ASSERT(colorAttachment < IMPLEMENTATION_MAX_DRAW_BUFFERS);
        return mColorbuffers[colorAttachment].mipLevel();
    }
    
    GLenum Framebuffer::getDepthbufferMipLevel() const
    {
        return mDepthbuffer.mipLevel();
    }
    
    GLenum Framebuffer::getStencilbufferMipLevel() const
    {
        return mStencilbuffer.mipLevel();
    }
    
    GLenum Framebuffer::getDepthStencilbufferMipLevel() const
    {
        return (mDepthbuffer.id() == mStencilbuffer.id()) ? mDepthbuffer.mipLevel() : 0;
    }
    
    GLenum Framebuffer::getColorbufferLayer(unsigned int colorAttachment) const
    {
        ASSERT(colorAttachment < IMPLEMENTATION_MAX_DRAW_BUFFERS);
        return mColorbuffers[colorAttachment].layer();
    }
    
    GLenum Framebuffer::getDepthbufferLayer() const
    {
        return mDepthbuffer.layer();
    }
    
    GLenum Framebuffer::getStencilbufferLayer() const
    {
        return mStencilbuffer.layer();
    }
    
    GLenum Framebuffer::getDepthStencilbufferLayer() const
    {
        return (mDepthbuffer.id() == mStencilbuffer.id()) ? mDepthbuffer.layer() : 0;
    }
    
    GLenum Framebuffer::getDrawBufferState(unsigned int colorAttachment) const
    {
        return mDrawBufferStates[colorAttachment];
    }
    
    void Framebuffer::setDrawBufferState(unsigned int colorAttachment, GLenum drawBuffer)
    {
        mDrawBufferStates[colorAttachment] = drawBuffer;
    }
    
    bool Framebuffer::isEnabledColorAttachment(unsigned int colorAttachment) const
    {
        return (mColorbuffers[colorAttachment].type() != GL_NONE && mDrawBufferStates[colorAttachment] != GL_NONE);
    }
    
    bool Framebuffer::hasEnabledColorAttachment() const
    {
        for (unsigned int colorAttachment = 0; colorAttachment < gl::IMPLEMENTATION_MAX_DRAW_BUFFERS; colorAttachment++)
        {
            if (isEnabledColorAttachment(colorAttachment))
            {
                return true;
            }
        }
    
        return false;
    }
    
    bool Framebuffer::hasStencil() const
    {
        if (mStencilbuffer.type() != GL_NONE)
        {
            const Renderbuffer *stencilbufferObject = getStencilbuffer();
    
            if (stencilbufferObject)
            {
                return stencilbufferObject->getStencilSize() > 0;
            }
        }
    
        return false;
    }
    
    bool Framebuffer::usingExtendedDrawBuffers() const
    {
        for (unsigned int colorAttachment = 1; colorAttachment < IMPLEMENTATION_MAX_DRAW_BUFFERS; colorAttachment++)
        {
            if (isEnabledColorAttachment(colorAttachment))
            {
                return true;
            }
        }
    
        return false;
    }
    
    GLenum Framebuffer::completeness() const
    {
        int width = 0;
        int height = 0;
        unsigned int colorbufferSize = 0;
        int samples = -1;
        bool missingAttachment = true;
        GLuint clientVersion = mRenderer->getCurrentClientVersion();
    
        for (unsigned int colorAttachment = 0; colorAttachment < IMPLEMENTATION_MAX_DRAW_BUFFERS; colorAttachment++)
        {
            if (mColorbuffers[colorAttachment].type() != GL_NONE)
            {
                const Renderbuffer *colorbuffer = getColorbuffer(colorAttachment);
    
                if (!colorbuffer)
                {
                    return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
                }
    
                if (colorbuffer->getWidth() == 0 || colorbuffer->getHeight() == 0)
                {
                    return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
                }
    
                if (mColorbuffers[colorAttachment].type() == GL_RENDERBUFFER)
                {
                    if (!gl::IsColorRenderingSupported(colorbuffer->getInternalFormat(), mRenderer))
                    {
                        return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
                    }
                }
                else if (IsInternalTextureTarget(mColorbuffers[colorAttachment].type(), mRenderer->getCurrentClientVersion()))
                {
                    GLenum internalformat = colorbuffer->getInternalFormat();
    
                    if (!gl::IsColorRenderingSupported(internalformat, mRenderer))
                    {
                        return GL_FRAMEBUFFER_UNSUPPORTED;
                    }
    
                    if (gl::GetDepthBits(internalformat, clientVersion) > 0 ||
                        gl::GetStencilBits(internalformat, clientVersion) > 0)
                    {
                        return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
                    }
                }
                else
                {
                    UNREACHABLE();
                    return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
                }
    
                if (!missingAttachment)
                {
                    // all color attachments must have the same width and height
                    if (colorbuffer->getWidth() != width || colorbuffer->getHeight() != height)
                    {
                        return GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS;
                    }
    
                    // APPLE_framebuffer_multisample, which EXT_draw_buffers refers to, requires that
                    // all color attachments have the same number of samples for the FBO to be complete.
                    if (colorbuffer->getSamples() != samples)
                    {
                        return GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE_EXT;
                    }
    
                    // in GLES 2.0, all color attachments attachments must have the same number of bitplanes
                    // in GLES 3.0, there is no such restriction
                    if (clientVersion < 3)
                    {
                        if (gl::GetPixelBytes(colorbuffer->getInternalFormat(), clientVersion) != colorbufferSize)
                        {
                            return GL_FRAMEBUFFER_UNSUPPORTED;
                        }
                    }
    
                    // D3D11 does not allow for overlapping RenderTargetViews, so ensure uniqueness
                    for (unsigned int previousColorAttachment = 0; previousColorAttachment < colorAttachment; previousColorAttachment++)
                    {
                        if (mColorbuffers[colorAttachment].get() == mColorbuffers[previousColorAttachment].get())
                        {
                            return GL_FRAMEBUFFER_UNSUPPORTED;
                        }
                    }
                }
                else
                {
                    width = colorbuffer->getWidth();
                    height = colorbuffer->getHeight();
                    samples = colorbuffer->getSamples();
                    colorbufferSize = gl::GetPixelBytes(colorbuffer->getInternalFormat(), clientVersion);
                    missingAttachment = false;
                }
            }
        }
    
        const Renderbuffer *depthbuffer = NULL;
        const Renderbuffer *stencilbuffer = NULL;
    
        if (mDepthbuffer.type() != GL_NONE)
        {
            depthbuffer = getDepthbuffer();
    
            if (!depthbuffer)
            {
                return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
            }
    
            if (depthbuffer->getWidth() == 0 || depthbuffer->getHeight() == 0)
            {
                return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
            }
    
            if (mDepthbuffer.type() == GL_RENDERBUFFER)
            {
                if (!gl::IsDepthRenderingSupported(depthbuffer->getInternalFormat(), mRenderer))
                {
                    return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
                }
            }
            else if (IsInternalTextureTarget(mDepthbuffer.type(), mRenderer->getCurrentClientVersion()))
            {
                GLenum internalformat = depthbuffer->getInternalFormat();
    
                // depth texture attachments require OES/ANGLE_depth_texture
                if (!mRenderer->getDepthTextureSupport())
                {
                    return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
                }
    
                if (gl::GetDepthBits(internalformat, clientVersion) == 0)
                {
                    return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
                }
            }
            else
            {
                UNREACHABLE();
                return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
            }
    
            if (missingAttachment)
            {
                width = depthbuffer->getWidth();
                height = depthbuffer->getHeight();
                samples = depthbuffer->getSamples();
                missingAttachment = false;
            }
            else if (width != depthbuffer->getWidth() || height != depthbuffer->getHeight())
            {
                return GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS;
            }
            else if (samples != depthbuffer->getSamples())
            {
                return GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE_ANGLE;
            }
        }
    
        if (mStencilbuffer.type() != GL_NONE)
        {
            stencilbuffer = getStencilbuffer();
    
            if (!stencilbuffer)
            {
                return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
            }
    
            if (stencilbuffer->getWidth() == 0 || stencilbuffer->getHeight() == 0)
            {
                return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
            }
    
            if (mStencilbuffer.type() == GL_RENDERBUFFER)
            {
                if (!gl::IsStencilRenderingSupported(stencilbuffer->getInternalFormat(), mRenderer))
                {
                    return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
                }
            }
            else if (IsInternalTextureTarget(mStencilbuffer.type(), mRenderer->getCurrentClientVersion()))
            {
                GLenum internalformat = stencilbuffer->getInternalFormat();
    
                // texture stencil attachments come along as part
                // of OES_packed_depth_stencil + OES/ANGLE_depth_texture
                if (!mRenderer->getDepthTextureSupport())
                {
                    return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
                }
    
                if (gl::GetStencilBits(internalformat, clientVersion) == 0)
                {
                    return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
                }
            }
            else
            {
                UNREACHABLE();
                return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
            }
    
            if (missingAttachment)
            {
                width = stencilbuffer->getWidth();
                height = stencilbuffer->getHeight();
                samples = stencilbuffer->getSamples();
                missingAttachment = false;
            }
            else if (width != stencilbuffer->getWidth() || height != stencilbuffer->getHeight())
            {
                return GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS;
            }
            else if (samples != stencilbuffer->getSamples())
            {
                return GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE_ANGLE;
            }
        }
    
        // if we have both a depth and stencil buffer, they must refer to the same object
        // since we only support packed_depth_stencil and not separate depth and stencil
        if (depthbuffer && stencilbuffer && (depthbuffer != stencilbuffer))
        {
            return GL_FRAMEBUFFER_UNSUPPORTED;
        }
    
        // we need to have at least one attachment to be complete
        if (missingAttachment)
        {
            return GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT;
        }
    
        return GL_FRAMEBUFFER_COMPLETE;
    }
    
    DefaultFramebuffer::DefaultFramebuffer(rx::Renderer *renderer, Colorbuffer *colorbuffer, DepthStencilbuffer *depthStencil)
        : Framebuffer(renderer)
    {
        mColorbuffers[0].set(new Renderbuffer(mRenderer, 0, colorbuffer), GL_RENDERBUFFER, 0, 0);
    
        Renderbuffer *depthStencilRenderbuffer = new Renderbuffer(mRenderer, 0, depthStencil);
        mDepthbuffer.set(depthStencilRenderbuffer, (depthStencilRenderbuffer->getDepthSize() != 0) ? GL_RENDERBUFFER : GL_NONE, 0, 0);
        mStencilbuffer.set(depthStencilRenderbuffer, (depthStencilRenderbuffer->getStencilSize() != 0) ? GL_RENDERBUFFER : GL_NONE, 0, 0);
    
        mDrawBufferStates[0] = GL_BACK;
        mReadBufferState = GL_BACK;
    }
    
    int Framebuffer::getSamples() const
    {
        if (completeness() == GL_FRAMEBUFFER_COMPLETE)
        {
            // for a complete framebuffer, all attachments must have the same sample count
            // in this case return the first nonzero sample size
            for (unsigned int colorAttachment = 0; colorAttachment < IMPLEMENTATION_MAX_DRAW_BUFFERS; colorAttachment++)
            {
                if (mColorbuffers[colorAttachment].type() != GL_NONE)
                {
                    return getColorbuffer(colorAttachment)->getSamples();
                }
            }
        }
    
        return 0;
    }
    
    GLenum DefaultFramebuffer::completeness() const
    {
        // The default framebuffer *must* always be complete, though it may not be
        // subject to the same rules as application FBOs. ie, it could have 0x0 size.
        return GL_FRAMEBUFFER_COMPLETE;
    }
    
    }