/*
-----------------------------------------------------------------------------
This source file is part of OGRE
    (Object-oriented Graphics Rendering Engine)
For the latest info, see http://www.ogre3d.org/

Copyright (c) 2000-2009 Torus Knot Software Ltd

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
-----------------------------------------------------------------------------
*/
#include "OgreGLHardwarePixelBuffer.h"
#include "OgreGLTexture.h"
#include "OgreGLSupport.h"
#include "OgreGLPixelFormat.h"
#include "OgreException.h"
#include "OgreLogManager.h"
#include "OgreStringConverter.h"
#include "OgreBitwise.h"
#include "OgreGLFBORenderTexture.h"
#include "OgreRoot.h"

namespace Ogre {
//----------------------------------------------------------------------------- 
GLHardwarePixelBuffer::GLHardwarePixelBuffer(size_t mWidth, size_t mHeight, size_t mDepth,
                PixelFormat mFormat,
                HardwareBuffer::Usage usage):
      HardwarePixelBuffer(mWidth, mHeight, mDepth, mFormat, usage, false, false),
      mBuffer(mWidth, mHeight, mDepth, mFormat),
      mGLInternalFormat(GL_NONE)
{
}

//-----------------------------------------------------------------------------  
GLHardwarePixelBuffer::~GLHardwarePixelBuffer()
{
	// Force free buffer
	delete [] (uint8*)mBuffer.data;
}
//-----------------------------------------------------------------------------  
void GLHardwarePixelBuffer::allocateBuffer()
{
	if(mBuffer.data)
		// Already allocated
		return;
	mBuffer.data = new uint8[mSizeInBytes];
	// TODO: use PBO if we're HBU_DYNAMIC
}
//-----------------------------------------------------------------------------  
void GLHardwarePixelBuffer::freeBuffer()
{
	// Free buffer if we're STATIC to save memory
	if(mUsage & HBU_STATIC)
	{
		delete [] (uint8*)mBuffer.data;
		mBuffer.data = 0;
	}
}
//-----------------------------------------------------------------------------  
PixelBox GLHardwarePixelBuffer::lockImpl(const Image::Box lockBox,  LockOptions options)
{
	allocateBuffer();
	if(options != HardwareBuffer::HBL_DISCARD) 
	{
		// Download the old contents of the texture
		download(mBuffer);
	}
	mCurrentLockOptions = options;
	mLockedBox = lockBox;
	return mBuffer.getSubVolume(lockBox);
}
//-----------------------------------------------------------------------------  
void GLHardwarePixelBuffer::unlockImpl(void)
{
	if (mCurrentLockOptions != HardwareBuffer::HBL_READ_ONLY)
	{
		// From buffer to card, only upload if was locked for writing
		upload(mCurrentLock, mLockedBox);
	}
	
	freeBuffer();
}

//-----------------------------------------------------------------------------  
void GLHardwarePixelBuffer::blitFromMemory(const PixelBox &src, const Image::Box &dstBox)
{
	if(!mBuffer.contains(dstBox))
		OGRE_EXCEPT(Exception::ERR_INVALIDPARAMS, "destination box out of range",
		 "GLHardwarePixelBuffer::blitFromMemory");
	PixelBox scaled;
	
	if(src.getWidth() != dstBox.getWidth() ||
		src.getHeight() != dstBox.getHeight() ||
		src.getDepth() != dstBox.getDepth())
	{
		// Scale to destination size. Use DevIL and not iluScale because ILU screws up for 
		// floating point textures and cannot cope with 3D images.
		// This also does pixel format conversion if needed
		allocateBuffer();
		scaled = mBuffer.getSubVolume(dstBox);
		Image::scale(src, scaled, Image::FILTER_BILINEAR);
	}
	else if(GLPixelUtil::getGLOriginFormat(src.format) == 0)
	{
		// Extents match, but format is not accepted as valid source format for GL
		// do conversion in temporary buffer
		allocateBuffer();
		scaled = mBuffer.getSubVolume(dstBox);
		PixelUtil::bulkPixelConversion(src, scaled);
	}
	else
	{
		allocateBuffer();
		// No scaling or conversion needed
		scaled = src;
	}
	
	upload(scaled, dstBox);
	freeBuffer();
}
//-----------------------------------------------------------------------------  
void GLHardwarePixelBuffer::blitToMemory(const Image::Box &srcBox, const PixelBox &dst)
{
	if(!mBuffer.contains(srcBox))
		OGRE_EXCEPT(Exception::ERR_INVALIDPARAMS, "source box out of range",
		 "GLHardwarePixelBuffer::blitToMemory");
	if(srcBox.left == 0 && srcBox.right == getWidth() &&
	   srcBox.top == 0 && srcBox.bottom == getHeight() &&
	   srcBox.front == 0 && srcBox.back == getDepth() &&
	   dst.getWidth() == getWidth() &&
	   dst.getHeight() == getHeight() &&
	   dst.getDepth() == getDepth() &&
	   GLPixelUtil::getGLOriginFormat(dst.format) != 0)
	{
		// The direct case: the user wants the entire texture in a format supported by GL
		// so we don't need an intermediate buffer
		download(dst);
	}
	else
	{
		// Use buffer for intermediate copy
		allocateBuffer();
		// Download entire buffer
		download(mBuffer);
		if(srcBox.getWidth() != dst.getWidth() ||
			srcBox.getHeight() != dst.getHeight() ||
			srcBox.getDepth() != dst.getDepth())
		{
			// We need scaling
			Image::scale(mBuffer.getSubVolume(srcBox), dst, Image::FILTER_BILINEAR);
		}
		else
		{
			// Just copy the bit that we need
			PixelUtil::bulkPixelConversion(mBuffer.getSubVolume(srcBox), dst);
		}
		freeBuffer();
	}
}
//-----------------------------------------------------------------------------
void GLHardwarePixelBuffer::upload(const PixelBox &data, const Image::Box &dest)
{
    OGRE_EXCEPT(Exception::ERR_RENDERINGAPI_ERROR, 
		"Upload not possible for this pixelbuffer type",
        "GLHardwarePixelBuffer::upload");
}
//-----------------------------------------------------------------------------  
void GLHardwarePixelBuffer::download(const PixelBox &data)
{
    OGRE_EXCEPT(Exception::ERR_RENDERINGAPI_ERROR, "Download not possible for this pixelbuffer type",
        "GLHardwarePixelBuffer::download");
}
//-----------------------------------------------------------------------------  
void GLHardwarePixelBuffer::bindToFramebuffer(GLenum attachment, size_t zoffset)
{
    OGRE_EXCEPT(Exception::ERR_RENDERINGAPI_ERROR, "Framebuffer bind not possible for this pixelbuffer type",
        "GLHardwarePixelBuffer::bindToFramebuffer");
}
//********* GLTextureBuffer
GLTextureBuffer::GLTextureBuffer(const String &baseName, GLenum target, GLuint id, 
								 GLint face, GLint level, Usage usage, bool crappyCard, 
								 bool writeGamma, uint fsaa):
	GLHardwarePixelBuffer(0, 0, 0, PF_UNKNOWN, usage),
	mTarget(target), mTextureID(id), mFace(face), mLevel(level), mSoftwareMipmap(crappyCard)
{
	// devise mWidth, mHeight and mDepth and mFormat
	GLint value;
	
	glBindTexture( mTarget, mTextureID );
	
	// Get face identifier
	mFaceTarget = mTarget;
	if(mTarget == GL_TEXTURE_CUBE_MAP)
		mFaceTarget = GL_TEXTURE_CUBE_MAP_POSITIVE_X + face;
	
	// Get width
	glGetTexLevelParameteriv(mFaceTarget, level, GL_TEXTURE_WIDTH, &value);
	mWidth = value;
	
	// Get height
	if(target == GL_TEXTURE_1D)
		value = 1;	// Height always 1 for 1D textures
	else
		glGetTexLevelParameteriv(mFaceTarget, level, GL_TEXTURE_HEIGHT, &value);
	mHeight = value;
	
	// Get depth
	if(target != GL_TEXTURE_3D)
		value = 1; // Depth always 1 for non-3D textures
	else
		glGetTexLevelParameteriv(mFaceTarget, level, GL_TEXTURE_DEPTH, &value);
	mDepth = value;

	// Get format
	glGetTexLevelParameteriv(mFaceTarget, level, GL_TEXTURE_INTERNAL_FORMAT, &value);
	mGLInternalFormat = value;
	mFormat = GLPixelUtil::getClosestOGREFormat(value);
	
	// Default
	mRowPitch = mWidth;
	mSlicePitch = mHeight*mWidth;
	mSizeInBytes = PixelUtil::getMemorySize(mWidth, mHeight, mDepth, mFormat);
	
	// Log a message
	/*
	std::stringstream str;
	str << "GLHardwarePixelBuffer constructed for texture " << mTextureID 
		<< " face " << mFace << " level " << mLevel << ": "
		<< "width=" << mWidth << " height="<< mHeight << " depth=" << mDepth
		<< "format=" << PixelUtil::getFormatName(mFormat) << "(internal 0x"
		<< std::hex << value << ")";
	LogManager::getSingleton().logMessage( 
                LML_NORMAL, str.str());
	*/
	// Set up pixel box
	mBuffer = PixelBox(mWidth, mHeight, mDepth, mFormat);
	
    if(mWidth==0 || mHeight==0 || mDepth==0)
        /// We are invalid, do not allocate a buffer
        return;
	// Allocate buffer
	//if(mUsage & HBU_STATIC)
	//	allocateBuffer();
    // Is this a render target?
    if(mUsage & TU_RENDERTARGET)
    {
        // Create render target for each slice
        mSliceTRT.reserve(mDepth);
        for(size_t zoffset=0; zoffset<mDepth; ++zoffset)
        {
            String name;
			name = "rtt/" + StringConverter::toString((size_t)this) + "/" + baseName;
            GLSurfaceDesc target;
            target.buffer = this;
            target.zoffset = zoffset;
            RenderTexture *trt = GLRTTManager::getSingleton().createRenderTexture(name, target, writeGamma, fsaa);
            mSliceTRT.push_back(trt);
            Root::getSingleton().getRenderSystem()->attachRenderTarget(*mSliceTRT[zoffset]);
        }
	}
}
GLTextureBuffer::~GLTextureBuffer()
{
    if(mUsage & TU_RENDERTARGET)
    {
        // Delete all render targets that are not yet deleted via _clearSliceRTT because the rendertarget
        // was deleted by the user.
        for (SliceTRT::const_iterator it = mSliceTRT.begin(); it != mSliceTRT.end(); ++it)
        {
            Root::getSingleton().getRenderSystem()->destroyRenderTarget((*it)->getName());
        }
	}
}
//-----------------------------------------------------------------------------
void GLTextureBuffer::upload(const PixelBox &data, const Image::Box &dest)
{
	glBindTexture( mTarget, mTextureID );
	if(PixelUtil::isCompressed(data.format))
	{
		if(data.format != mFormat || !data.isConsecutive())
			OGRE_EXCEPT(Exception::ERR_INVALIDPARAMS, 
			"Compressed images must be consecutive, in the source format",
		 	"GLTextureBuffer::upload");
		GLenum format = GLPixelUtil::getClosestGLInternalFormat(mFormat);
		// Data must be consecutive and at beginning of buffer as PixelStorei not allowed
		// for compressed formats
		switch(mTarget) {
			case GL_TEXTURE_1D:
				// some systems (e.g. old Apple) don't like compressed subimage calls
				// so prefer non-sub versions
				if (dest.left == 0)
				{
					glCompressedTexImage1DARB(GL_TEXTURE_1D, mLevel,
						format,
						dest.getWidth(),
						0,
						data.getConsecutiveSize(),
						data.data);
				}
				else
				{
					glCompressedTexSubImage1DARB(GL_TEXTURE_1D, mLevel, 
						dest.left,
						dest.getWidth(),
						format, data.getConsecutiveSize(),
						data.data);
				}
				break;
			case GL_TEXTURE_2D:
			case GL_TEXTURE_CUBE_MAP:
				// some systems (e.g. old Apple) don't like compressed subimage calls
				// so prefer non-sub versions
				if (dest.left == 0 && dest.top == 0)
				{
					glCompressedTexImage2DARB(mFaceTarget, mLevel,
						format,
						dest.getWidth(),
						dest.getHeight(),
						0,
						data.getConsecutiveSize(),
						data.data);
				}
				else
				{
					glCompressedTexSubImage2DARB(mFaceTarget, mLevel, 
						dest.left, dest.top, 
						dest.getWidth(), dest.getHeight(),
						format, data.getConsecutiveSize(),
						data.data);
				}
				break;
			case GL_TEXTURE_3D:
				// some systems (e.g. old Apple) don't like compressed subimage calls
				// so prefer non-sub versions
				if (dest.left == 0 && dest.top == 0 && dest.front == 0)
				{
					glCompressedTexImage3DARB(GL_TEXTURE_3D, mLevel,
						format,
						dest.getWidth(),
						dest.getHeight(),
						dest.getDepth(),
						0,
						data.getConsecutiveSize(),
						data.data);
				}
				else
				{			
					glCompressedTexSubImage3DARB(GL_TEXTURE_3D, mLevel, 
						dest.left, dest.top, dest.front,
						dest.getWidth(), dest.getHeight(), dest.getDepth(),
						format, data.getConsecutiveSize(),
						data.data);
				}
				break;
		}
		
	} 
	else if(mSoftwareMipmap)
	{
		GLint components = PixelUtil::getComponentCount(mFormat);
		if(data.getWidth() != data.rowPitch)
			glPixelStorei(GL_UNPACK_ROW_LENGTH, data.rowPitch);
		if(data.getHeight()*data.getWidth() != data.slicePitch)
			glPixelStorei(GL_UNPACK_IMAGE_HEIGHT, (data.slicePitch/data.getWidth()));
		if(data.left > 0 || data.top > 0 || data.front > 0)
			glPixelStorei(GL_UNPACK_SKIP_PIXELS, data.left + data.rowPitch * data.top + data.slicePitch * data.front);
		glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
		
		switch(mTarget)
		{
		case GL_TEXTURE_1D:
			gluBuild1DMipmaps(
				GL_TEXTURE_1D, components,
				dest.getWidth(),
				GLPixelUtil::getGLOriginFormat(data.format), GLPixelUtil::getGLOriginDataType(data.format),
				data.data);
			break;
		case GL_TEXTURE_2D:
		case GL_TEXTURE_CUBE_MAP:
			gluBuild2DMipmaps(
				mFaceTarget,
				components, dest.getWidth(), dest.getHeight(), 
				GLPixelUtil::getGLOriginFormat(data.format), GLPixelUtil::getGLOriginDataType(data.format), 
				data.data);
			break;		
		case GL_TEXTURE_3D:
			/* Requires GLU 1.3 which is harder to come by than cards doing hardware mipmapping
				Most 3D textures don't need mipmaps?
			gluBuild3DMipmaps(
				GL_TEXTURE_3D, internalFormat, 
				data.getWidth(), data.getHeight(), data.getDepth(),
				GLPixelUtil::getGLOriginFormat(data.format), GLPixelUtil::getGLOriginDataType(data.format),
				data.data);
			*/
			glTexImage3D(
				GL_TEXTURE_3D, 0, components, 
				dest.getWidth(), dest.getHeight(), dest.getDepth(), 0, 
				GLPixelUtil::getGLOriginFormat(data.format), GLPixelUtil::getGLOriginDataType(data.format),
				data.data );
			break;
		}
	} 
	else
	{
		if(data.getWidth() != data.rowPitch)
			glPixelStorei(GL_UNPACK_ROW_LENGTH, data.rowPitch);
		if(data.getHeight()*data.getWidth() != data.slicePitch)
			glPixelStorei(GL_UNPACK_IMAGE_HEIGHT, (data.slicePitch/data.getWidth()));
		if(data.left > 0 || data.top > 0 || data.front > 0)
			glPixelStorei(GL_UNPACK_SKIP_PIXELS, data.left + data.rowPitch * data.top + data.slicePitch * data.front);
		if((data.getWidth()*PixelUtil::getNumElemBytes(data.format)) & 3) {
			// Standard alignment of 4 is not right
			glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
		}
		switch(mTarget) {
			case GL_TEXTURE_1D:
				glTexSubImage1D(GL_TEXTURE_1D, mLevel, 
					dest.left,
					dest.getWidth(),
					GLPixelUtil::getGLOriginFormat(data.format), GLPixelUtil::getGLOriginDataType(data.format),
					data.data);
				break;
			case GL_TEXTURE_2D:
			case GL_TEXTURE_CUBE_MAP:
				glTexSubImage2D(mFaceTarget, mLevel, 
					dest.left, dest.top, 
					dest.getWidth(), dest.getHeight(),
					GLPixelUtil::getGLOriginFormat(data.format), GLPixelUtil::getGLOriginDataType(data.format),
					data.data);
				break;
			case GL_TEXTURE_3D:
				glTexSubImage3D(
					GL_TEXTURE_3D, mLevel, 
					dest.left, dest.top, dest.front,
					dest.getWidth(), dest.getHeight(), dest.getDepth(),
					GLPixelUtil::getGLOriginFormat(data.format), GLPixelUtil::getGLOriginDataType(data.format),
					data.data);
				break;
		}	
	}
	// Restore defaults
	glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
	if (GLEW_VERSION_1_2)
		glPixelStorei(GL_UNPACK_IMAGE_HEIGHT, 0);
	glPixelStorei(GL_UNPACK_SKIP_PIXELS, 0);
	glPixelStorei(GL_UNPACK_ALIGNMENT, 4);
}
//-----------------------------------------------------------------------------  
void GLTextureBuffer::download(const PixelBox &data)
{
	if(data.getWidth() != getWidth() ||
		data.getHeight() != getHeight() ||
		data.getDepth() != getDepth())
		OGRE_EXCEPT(Exception::ERR_INVALIDPARAMS, "only download of entire buffer is supported by GL",
		 	"GLTextureBuffer::download");
	glBindTexture( mTarget, mTextureID );
	if(PixelUtil::isCompressed(data.format))
	{
		if(data.format != mFormat || !data.isConsecutive())
			OGRE_EXCEPT(Exception::ERR_INVALIDPARAMS, 
			"Compressed images must be consecutive, in the source format",
		 	"GLTextureBuffer::download");
		// Data must be consecutive and at beginning of buffer as PixelStorei not allowed
		// for compressed formate
		glGetCompressedTexImageARB(mFaceTarget, mLevel, data.data);
	} 
	else
	{
		if(data.getWidth() != data.rowPitch)
			glPixelStorei(GL_PACK_ROW_LENGTH, data.rowPitch);
		if(data.getHeight()*data.getWidth() != data.slicePitch)
			glPixelStorei(GL_PACK_IMAGE_HEIGHT, (data.slicePitch/data.getWidth()));
		if(data.left > 0 || data.top > 0 || data.front > 0)
			glPixelStorei(GL_PACK_SKIP_PIXELS, data.left + data.rowPitch * data.top + data.slicePitch * data.front);
		if((data.getWidth()*PixelUtil::getNumElemBytes(data.format)) & 3) {
			// Standard alignment of 4 is not right
			glPixelStorei(GL_PACK_ALIGNMENT, 1);
		}
		// We can only get the entire texture
		glGetTexImage(mFaceTarget, mLevel, 
			GLPixelUtil::getGLOriginFormat(data.format), GLPixelUtil::getGLOriginDataType(data.format),
			data.data);
		// Restore defaults
		glPixelStorei(GL_PACK_ROW_LENGTH, 0);
		glPixelStorei(GL_PACK_IMAGE_HEIGHT, 0);
		glPixelStorei(GL_PACK_SKIP_PIXELS, 0);
		glPixelStorei(GL_PACK_ALIGNMENT, 4);
	}
}
//-----------------------------------------------------------------------------  
void GLTextureBuffer::bindToFramebuffer(GLenum attachment, size_t zoffset)
{
    assert(zoffset < mDepth);
    switch(mTarget)
    {
    case GL_TEXTURE_1D:
        glFramebufferTexture1DEXT(GL_FRAMEBUFFER_EXT, attachment,
                            mFaceTarget, mTextureID, mLevel);
        break;
    case GL_TEXTURE_2D:
    case GL_TEXTURE_CUBE_MAP:
        glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, attachment,
                            mFaceTarget, mTextureID, mLevel);
        break;
    case GL_TEXTURE_3D:
        glFramebufferTexture3DEXT(GL_FRAMEBUFFER_EXT, attachment,
                            mFaceTarget, mTextureID, mLevel, zoffset);
        break;
    }
}
//-----------------------------------------------------------------------------
void GLTextureBuffer::copyFromFramebuffer(size_t zoffset)
{
    glBindTexture(mTarget, mTextureID);
    switch(mTarget)
    {
    case GL_TEXTURE_1D:
        glCopyTexSubImage1D(mFaceTarget, mLevel, 0, 0, 0, mWidth);
        break;
    case GL_TEXTURE_2D:
    case GL_TEXTURE_CUBE_MAP:
        glCopyTexSubImage2D(mFaceTarget, mLevel, 0, 0, 0, 0, mWidth, mHeight);
        break;
    case GL_TEXTURE_3D:
        glCopyTexSubImage3D(mFaceTarget, mLevel, 0, 0, zoffset, 0, 0, mWidth, mHeight);
        break;
    }
}
//-----------------------------------------------------------------------------  
void GLTextureBuffer::blit(const HardwarePixelBufferSharedPtr &src, const Image::Box &srcBox, const Image::Box &dstBox)
{
    GLTextureBuffer *srct = static_cast<GLTextureBuffer *>(src.getPointer());
    /// Check for FBO support first
    /// Destination texture must be 1D, 2D, 3D, or Cube
    /// Source texture must be 1D, 2D or 3D
	
	// This does not sem to work for RTTs after the first update
	// I have no idea why! For the moment, disable 
    if(GLEW_EXT_framebuffer_object && (src->getUsage() & TU_RENDERTARGET) == 0 &&
        (srct->mTarget==GL_TEXTURE_1D||srct->mTarget==GL_TEXTURE_2D||srct->mTarget==GL_TEXTURE_3D))
    {
        blitFromTexture(srct, srcBox, dstBox);
    }
    else
    {
        GLHardwarePixelBuffer::blit(src, srcBox, dstBox);
    }
}

//-----------------------------------------------------------------------------  
/// Very fast texture-to-texture blitter and hardware bi/trilinear scaling implementation using FBO
/// Destination texture must be 1D, 2D, 3D, or Cube
/// Source texture must be 1D, 2D or 3D
/// Supports compressed formats as both source and destination format, it will use the hardware DXT compressor
/// if available.
/// @author W.J. van der Laan
void GLTextureBuffer::blitFromTexture(GLTextureBuffer *src, const Image::Box &srcBox, const Image::Box &dstBox)
{
    //std::cerr << "GLTextureBuffer::blitFromTexture " <<
    //src->mTextureID << ":" << srcBox.left << "," << srcBox.top << "," << srcBox.right << "," << srcBox.bottom << " " << 
    //mTextureID << ":" << dstBox.left << "," << dstBox.top << "," << dstBox.right << "," << dstBox.bottom << std::endl;
    /// Store reference to FBO manager
    GLFBOManager *fboMan = static_cast<GLFBOManager *>(GLRTTManager::getSingletonPtr());
    
    /// Save and clear GL state for rendering
    glPushAttrib(GL_COLOR_BUFFER_BIT | GL_CURRENT_BIT | GL_DEPTH_BUFFER_BIT | GL_ENABLE_BIT | 
        GL_FOG_BIT | GL_LIGHTING_BIT | GL_POLYGON_BIT | GL_SCISSOR_BIT | GL_STENCIL_BUFFER_BIT |
        GL_TEXTURE_BIT | GL_VIEWPORT_BIT);

	// Important to disable all other texture units
	RenderSystem* rsys = Root::getSingleton().getRenderSystem();
	rsys->_disableTextureUnitsFrom(0);
	if (GLEW_VERSION_1_2)
	{
		glActiveTextureARB(GL_TEXTURE0);
	}


    /// Disable alpha, depth and scissor testing, disable blending, 
    /// disable culling, disble lighting, disable fog and reset foreground
    /// colour.
    glDisable(GL_ALPHA_TEST);
    glDisable(GL_DEPTH_TEST);
    glDisable(GL_SCISSOR_TEST);
    glDisable(GL_BLEND);
    glDisable(GL_CULL_FACE);
    glDisable(GL_LIGHTING);
    glDisable(GL_FOG);
    glColor4f(1.0f, 1.0f, 1.0f, 1.0f);
    
    /// Save and reset matrices
    glMatrixMode(GL_MODELVIEW);
    glPushMatrix();
    glLoadIdentity();
    glMatrixMode(GL_PROJECTION);
    glPushMatrix();
    glLoadIdentity();
    glMatrixMode(GL_TEXTURE);
    glPushMatrix();
    glLoadIdentity();
    
    /// Set up source texture
    glBindTexture(src->mTarget, src->mTextureID);
    
    /// Set filtering modes depending on the dimensions and source
    if(srcBox.getWidth()==dstBox.getWidth() &&
        srcBox.getHeight()==dstBox.getHeight() &&
        srcBox.getDepth()==dstBox.getDepth())
    {
        /// Dimensions match -- use nearest filtering (fastest and pixel correct)
        glTexParameteri(src->mTarget, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
        glTexParameteri(src->mTarget, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    }
    else
    {
        /// Dimensions don't match -- use bi or trilinear filtering depending on the
        /// source texture.
        if(src->mUsage & TU_AUTOMIPMAP)
        {
            /// Automatic mipmaps, we can safely use trilinear filter which
            /// brings greatly imporoved quality for minimisation.
            glTexParameteri(src->mTarget, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
            glTexParameteri(src->mTarget, GL_TEXTURE_MAG_FILTER, GL_LINEAR);    
        }
        else
        {
            /// Manual mipmaps, stay safe with bilinear filtering so that no
            /// intermipmap leakage occurs.
            glTexParameteri(src->mTarget, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
            glTexParameteri(src->mTarget, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
        }
    }
    /// Clamp to edge (fastest)
    glTexParameteri(src->mTarget, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(src->mTarget, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexParameteri(src->mTarget, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
    
    /// Set origin base level mipmap to make sure we source from the right mip
    /// level.
    glTexParameteri(src->mTarget, GL_TEXTURE_BASE_LEVEL, src->mLevel);
    
    /// Store old binding so it can be restored later
    GLint oldfb;
    glGetIntegerv(GL_FRAMEBUFFER_BINDING_EXT, &oldfb);
    
    /// Set up temporary FBO
    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fboMan->getTemporaryFBO());
    
    GLuint tempTex = 0;
    if(!fboMan->checkFormat(mFormat))
    {
        /// If target format not directly supported, create intermediate texture
        GLenum tempFormat = GLPixelUtil::getClosestGLInternalFormat(fboMan->getSupportedAlternative(mFormat));
        glGenTextures(1, &tempTex);
        glBindTexture(GL_TEXTURE_2D, tempTex);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);
        /// Allocate temporary texture of the size of the destination area
        glTexImage2D(GL_TEXTURE_2D, 0, tempFormat, 
            GLPixelUtil::optionalPO2(dstBox.getWidth()), GLPixelUtil::optionalPO2(dstBox.getHeight()), 
            0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
        glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT,
            GL_TEXTURE_2D, tempTex, 0);
        /// Set viewport to size of destination slice
        glViewport(0, 0, dstBox.getWidth(), dstBox.getHeight());
    }
    else
    {
        /// We are going to bind directly, so set viewport to size and position of destination slice
        glViewport(dstBox.left, dstBox.top, dstBox.getWidth(), dstBox.getHeight());
    }
    
    /// Process each destination slice
    for(size_t slice=dstBox.front; slice<dstBox.back; ++slice)
    {
        if(!tempTex)
        {
            /// Bind directly
            bindToFramebuffer(GL_COLOR_ATTACHMENT0_EXT, slice);
        }
        /// Calculate source texture coordinates
        float u1 = (float)srcBox.left / (float)src->mWidth;
        float v1 = (float)srcBox.top / (float)src->mHeight;
        float u2 = (float)srcBox.right / (float)src->mWidth;
        float v2 = (float)srcBox.bottom / (float)src->mHeight;
        /// Calculate source slice for this destination slice
        float w = (float)(slice - dstBox.front) / (float)dstBox.getDepth();
        /// Get slice # in source
        w = w * (float)srcBox.getDepth() + srcBox.front;
        /// Normalise to texture coordinate in 0.0 .. 1.0
        w = (w+0.5f) / (float)src->mDepth;
        
        /// Finally we're ready to rumble	
        glBindTexture(src->mTarget, src->mTextureID);
        glEnable(src->mTarget);
        glBegin(GL_QUADS);
        glTexCoord3f(u1, v1, w);
        glVertex2f(-1.0f, -1.0f);
        glTexCoord3f(u2, v1, w);
        glVertex2f(1.0f, -1.0f);
        glTexCoord3f(u2, v2, w);
        glVertex2f(1.0f, 1.0f);
        glTexCoord3f(u1, v2, w);
        glVertex2f(-1.0f, 1.0f);
        glEnd();
        glDisable(src->mTarget);
        
        if(tempTex)
        {
            /// Copy temporary texture
            glBindTexture(mTarget, mTextureID);
            switch(mTarget)
            {
            case GL_TEXTURE_1D:
                glCopyTexSubImage1D(mFaceTarget, mLevel, 
                    dstBox.left, 
                    0, 0, dstBox.getWidth());
                break;
            case GL_TEXTURE_2D:
            case GL_TEXTURE_CUBE_MAP:
                glCopyTexSubImage2D(mFaceTarget, mLevel, 
                    dstBox.left, dstBox.top, 
                    0, 0, dstBox.getWidth(), dstBox.getHeight());
                break;
            case GL_TEXTURE_3D:
                glCopyTexSubImage3D(mFaceTarget, mLevel, 
                    dstBox.left, dstBox.top, slice, 
                    0, 0, dstBox.getWidth(), dstBox.getHeight());
                break;
            }
        }
    }
    /// Finish up 
    if(!tempTex)
    {
        /// Generate mipmaps
        if(mUsage & TU_AUTOMIPMAP)
        {
            glBindTexture(mTarget, mTextureID);
            glGenerateMipmapEXT(mTarget);
        }
    }

    /// Reset source texture to sane state
    glBindTexture(src->mTarget, src->mTextureID);
    glTexParameteri(src->mTarget, GL_TEXTURE_BASE_LEVEL, 0);
    
    /// Detach texture from temporary framebuffer
    glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT,
                    GL_RENDERBUFFER_EXT, 0);
    /// Restore old framebuffer
    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, oldfb);
    /// Restore matrix stacks and render state
    glMatrixMode(GL_TEXTURE);
    glPopMatrix();
    glMatrixMode(GL_PROJECTION);
    glPopMatrix();
    glMatrixMode(GL_MODELVIEW);
    glPopMatrix();
    glPopAttrib();
    glDeleteTextures(1, &tempTex);
}
//-----------------------------------------------------------------------------  
/// blitFromMemory doing hardware trilinear scaling
void GLTextureBuffer::blitFromMemory(const PixelBox &src_orig, const Image::Box &dstBox)
{
    /// Fall back to normal GLHardwarePixelBuffer::blitFromMemory in case 
    /// - FBO is not supported
    /// - Either source or target is luminance due doesn't looks like supported by hardware
    /// - the source dimensions match the destination ones, in which case no scaling is needed
    if(!GLEW_EXT_framebuffer_object ||
        PixelUtil::isLuminance(src_orig.format) ||
        PixelUtil::isLuminance(mFormat) ||
        (src_orig.getWidth() == dstBox.getWidth() &&
        src_orig.getHeight() == dstBox.getHeight() &&
        src_orig.getDepth() == dstBox.getDepth()))
    {
        GLHardwarePixelBuffer::blitFromMemory(src_orig, dstBox);
        return;
    }
    if(!mBuffer.contains(dstBox))
        OGRE_EXCEPT(Exception::ERR_INVALIDPARAMS, "destination box out of range",
                    "GLTextureBuffer::blitFromMemory");
    /// For scoped deletion of conversion buffer
    MemoryDataStreamPtr buf;
    PixelBox src;
    
    /// First, convert the srcbox to a OpenGL compatible pixel format
    if(GLPixelUtil::getGLOriginFormat(src_orig.format) == 0)
    {
        /// Convert to buffer internal format
        buf.bind(new MemoryDataStream(
                PixelUtil::getMemorySize(src_orig.getWidth(), src_orig.getHeight(), src_orig.getDepth(),
                                         mFormat)));
        src = PixelBox(src_orig.getWidth(), src_orig.getHeight(), src_orig.getDepth(), mFormat, buf->getPtr());
        PixelUtil::bulkPixelConversion(src_orig, src);
    }
    else
    {
        /// No conversion needed
        src = src_orig;
    }
    
    /// Create temporary texture to store source data
    GLuint id;
    GLenum target = (src.getDepth()!=1)?GL_TEXTURE_3D:GL_TEXTURE_2D;
    GLsizei width = GLPixelUtil::optionalPO2(src.getWidth());
    GLsizei height = GLPixelUtil::optionalPO2(src.getHeight());
    GLsizei depth = GLPixelUtil::optionalPO2(src.getDepth());
    GLenum format = GLPixelUtil::getClosestGLInternalFormat(src.format);
    
    /// Generate texture name
    glGenTextures(1, &id);
    
    /// Set texture type
    glBindTexture(target, id);
    
    /// Set automatic mipmap generation; nice for minimisation
    glTexParameteri(target, GL_TEXTURE_MAX_LEVEL, 1000 );
    glTexParameteri(target, GL_GENERATE_MIPMAP, GL_TRUE );
    
    /// Allocate texture memory
    if(target == GL_TEXTURE_3D)
        glTexImage3D(target, 0, format, width, height, depth, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
    else
        glTexImage2D(target, 0, format, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);

    /// GL texture buffer
    GLTextureBuffer tex(StringUtil::BLANK, target, id, 0, 0, (Usage)(TU_AUTOMIPMAP|HBU_STATIC_WRITE_ONLY), false, false, 0);
    
    /// Upload data to 0,0,0 in temporary texture
	Image::Box tempTarget(0, 0, 0, src.getWidth(), src.getHeight(), src.getDepth());
    tex.upload(src, tempTarget);
    
    /// Blit
    blitFromTexture(&tex, tempTarget, dstBox);
    
    /// Delete temp texture
    glDeleteTextures(1, &id);
}
//-----------------------------------------------------------------------------    

RenderTexture *GLTextureBuffer::getRenderTarget(size_t zoffset)
{
    assert(mUsage & TU_RENDERTARGET);
    assert(zoffset < mDepth);
    return mSliceTRT[zoffset];
}
//********* GLRenderBuffer
//----------------------------------------------------------------------------- 
GLRenderBuffer::GLRenderBuffer(GLenum format, size_t width, size_t height, GLsizei numSamples):
    GLHardwarePixelBuffer(width, height, 1, GLPixelUtil::getClosestOGREFormat(format),HBU_WRITE_ONLY)
{
    mGLInternalFormat = format;
    /// Generate renderbuffer
    glGenRenderbuffersEXT(1, &mRenderbufferID);
    /// Bind it to FBO
    glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, mRenderbufferID);
    
    /// Allocate storage for depth buffer
	if (numSamples > 0)
	{
		glRenderbufferStorageMultisampleEXT(GL_RENDERBUFFER_EXT, 
			numSamples, format, width, height);
	}
	else
	{
		glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, format,
							width, height);
	}
}
//----------------------------------------------------------------------------- 
GLRenderBuffer::~GLRenderBuffer()
{
    /// Generate renderbuffer
    glDeleteRenderbuffersEXT(1, &mRenderbufferID);
}
//-----------------------------------------------------------------------------  
void GLRenderBuffer::bindToFramebuffer(GLenum attachment, size_t zoffset)
{
    assert(zoffset < mDepth);
    glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, attachment,
                        GL_RENDERBUFFER_EXT, mRenderbufferID);
}

};
