source: code/trunk/src/external/ogreceguirenderer/OgreCEGUIRenderer.cpp @ 8817

/************************************************************************
        filename:       OgreCEGUIRenderer.cpp
        created:        11/5/2004
        author:         Paul D Turner
        
        purpose:        Implementation of Renderer class for Ogre engine
*************************************************************************/
/*************************************************************************
    Crazy Eddie's GUI System (http://www.cegui.org.uk)
    Copyright (C)2004 - 2005 Paul D Turner (paul@cegui.org.uk)

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library 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
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*************************************************************************/

// Workaround for GCC 4.6
#include <cstddef>

#include <CEGUIImagesetManager.h>
#include <CEGUIImageset.h>
#include <CEGUIImage.h>
#include <CEGUIExceptions.h>
#include <CEGUISystem.h>

#include "OgreCEGUIRenderer.h"
#include "OgreCEGUITexture.h"
#include "OgreCEGUIResourceProvider.h"

#include <OgreRenderSystem.h>
#include <OgreRoot.h>
#include <OgreHardwareBufferManager.h>
#include <OgreRenderWindow.h>

// Start of CEGUI namespace section
namespace CEGUI
{
/*************************************************************************
        Constants definitions
*************************************************************************/
const size_t    OgreCEGUIRenderer::VERTEX_PER_QUAD                      = 6;
const size_t    OgreCEGUIRenderer::VERTEX_PER_TRIANGLE          = 3;
const size_t    OgreCEGUIRenderer::VERTEXBUFFER_INITIAL_CAPACITY        = 256;
const size_t    OgreCEGUIRenderer::UNDERUSED_FRAME_THRESHOLD = 50000; // halfs buffer every 8 minutes on 100fps

/*************************************************************************
        Utility function to create a render operation and vertex buffer to render quads
*************************************************************************/
static void createQuadRenderOp(Ogre::RenderOperation &d_render_op, 
    Ogre::HardwareVertexBufferSharedPtr &d_buffer, size_t nquads)
{
    using namespace Ogre;
    // Create and initialise the Ogre specific parts required for use in rendering later.
        d_render_op.vertexData = new VertexData;
        d_render_op.vertexData->vertexStart = 0;

        // setup vertex declaration for the vertex format we use
        VertexDeclaration* vd = d_render_op.vertexData->vertexDeclaration;
        size_t vd_offset = 0;
        vd->addElement(0, vd_offset, VET_FLOAT3, VES_POSITION);
        vd_offset += VertexElement::getTypeSize(VET_FLOAT3);
        vd->addElement(0, vd_offset, VET_COLOUR, VES_DIFFUSE);
        vd_offset += VertexElement::getTypeSize(VET_COLOUR);
        vd->addElement(0, vd_offset, VET_FLOAT2, VES_TEXTURE_COORDINATES);

        // create hardware vertex buffer
        d_buffer = HardwareBufferManager::getSingleton().createVertexBuffer(vd->getVertexSize(0), nquads,  
        HardwareBuffer::HBU_DYNAMIC_WRITE_ONLY_DISCARDABLE, false);

        // bind vertex buffer
        d_render_op.vertexData->vertexBufferBinding->setBinding(0, d_buffer);

        // complete render operation basic initialisation
        d_render_op.operationType = RenderOperation::OT_TRIANGLE_LIST;
        d_render_op.useIndexes = false;
}

static void destroyQuadRenderOp(Ogre::RenderOperation &d_render_op, 
    Ogre::HardwareVertexBufferSharedPtr &d_buffer)
{
    delete d_render_op.vertexData;
    d_render_op.vertexData = 0;
    d_buffer.setNull();
}

/*************************************************************************
        Constructor
*************************************************************************/
OgreCEGUIRenderer::OgreCEGUIRenderer(Ogre::RenderWindow* window, Ogre::uint8 queue_id, bool post_queue, uint max_quads)
{
        constructor_impl(window, queue_id, post_queue, max_quads);
}


/*************************************************************************
        Constructor (specifying scene manager)
*************************************************************************/
OgreCEGUIRenderer::OgreCEGUIRenderer(Ogre::RenderWindow* window, Ogre::uint8 queue_id, bool post_queue, uint max_quads, Ogre::SceneManager* scene_manager)
{
        constructor_impl(window, queue_id, post_queue, max_quads);

        // hook into ogre rendering system
        setTargetSceneManager(scene_manager);
}


/*************************************************************************
        Destructor
*************************************************************************/
OgreCEGUIRenderer::~OgreCEGUIRenderer(void)
{
        setTargetSceneManager(NULL);

        if (d_ourlistener)
        {
                delete d_ourlistener;
        }

        // cleanup vertex data we allocated in constructor
        destroyQuadRenderOp(d_render_op, d_buffer);
    destroyQuadRenderOp(d_direct_render_op, d_direct_buffer);

        destroyAllTextures();
}


/*************************************************************************
        add's a quad to the list to be rendered
*************************************************************************/
void OgreCEGUIRenderer::addQuad(const Rect& dest_rect, float z, const Texture* tex, const Rect& texture_rect, const ColourRect& colours, QuadSplitMode quad_split_mode)
{
        // if not queueing, render directly (as in, right now!). This is used for the mouse cursor.
        if (!d_queueing)
        {
                renderQuadDirect(dest_rect, z, tex, texture_rect, colours, quad_split_mode);
        }
        else
        {
                d_sorted = false;
                QuadInfo quad;
                
                // set quad position, flipping y co-ordinates, and applying appropriate texel origin offset
                quad.position.d_left    = dest_rect.d_left;
                quad.position.d_right   = dest_rect.d_right;
                quad.position.d_top             = d_display_area.getHeight() - dest_rect.d_top;
                quad.position.d_bottom  = d_display_area.getHeight() - dest_rect.d_bottom;
                quad.position.offset(d_texelOffset);

                // convert quad co-ordinates for a -1 to 1 co-ordinate system.
                quad.position.d_left    /= (d_display_area.getWidth() * 0.5f);
                quad.position.d_right   /= (d_display_area.getWidth() * 0.5f);
                quad.position.d_top             /= (d_display_area.getHeight() * 0.5f);
                quad.position.d_bottom  /= (d_display_area.getHeight() * 0.5f);
                quad.position.offset(Point(-1.0f, -1.0f));

                quad.z                          = -1 + z;
                quad.texture            = ((OgreCEGUITexture*)tex)->getOgreTexture();
                quad.texPosition        = texture_rect;

                // covert colours for ogre, note that top / bottom are switched.
                quad.topLeftCol         = colourToOgre(colours.d_bottom_left);
                quad.topRightCol        = colourToOgre(colours.d_bottom_right);
                quad.bottomLeftCol      = colourToOgre(colours.d_top_left);
                quad.bottomRightCol     = colourToOgre(colours.d_top_right);
                
                // set quad split mode
                quad.splitMode = quad_split_mode;

                d_quadlist.insert(quad);
        }
}



/*************************************************************************
perform final rendering for all queued renderable quads.
*************************************************************************/
void OgreCEGUIRenderer::doRender(void)
{
    // Render if overlays enabled and the quad list is not empty
        if (d_render_sys->_getViewport()->getOverlaysEnabled() && !d_quadlist.empty())
        {
        /// Quad list needs to be sorted and thus the vertex buffer rebuilt. If not, we can
        /// reuse the vertex buffer resulting in a nice speed gain.
        if(!d_sorted)
        {
            sortQuads();
            /// Resize vertex buffer if it is too small
            size_t size = d_buffer->getNumVertices();
            size_t requestedSize = d_quadlist.size()*VERTEX_PER_QUAD;
            if(size < requestedSize)
            {
                /// Double buffer size until smaller than requested size
                while(size < requestedSize)
                    size = size * 2;
                /// Reallocate the buffer
                destroyQuadRenderOp(d_render_op, d_buffer);
                createQuadRenderOp(d_render_op, d_buffer, size);
            }
            else if(requestedSize < size/2 && d_underused_framecount >= UNDERUSED_FRAME_THRESHOLD)
            {
                /// Resize vertex buffer if it has been to big for too long
                size = size / 2;
                destroyQuadRenderOp(d_render_op, d_buffer);
                createQuadRenderOp(d_render_op, d_buffer, size);
                /// Reset underused framecount so it takes another UNDERUSED_FRAME_THRESHOLD to half again
                d_underused_framecount = 0;
            }
            /// Fill the buffer
            QuadVertex* buffmem;
            buffmem = (QuadVertex*)d_buffer->lock(Ogre::HardwareVertexBuffer::HBL_DISCARD);
            // iterate over each quad in the list
            for (QuadList::iterator i = d_quadlist.begin(); i != d_quadlist.end(); ++i)
            {
                const QuadInfo& quad = (*i);
                // setup Vertex 1...
                buffmem->x = quad.position.d_left;
                buffmem->y = quad.position.d_bottom;
                buffmem->z = quad.z;
                buffmem->diffuse = quad.topLeftCol;
                buffmem->tu1 = quad.texPosition.d_left;
                buffmem->tv1 = quad.texPosition.d_bottom;
                ++buffmem;
    
                // setup Vertex 2...
                
                // top-left to bottom-right diagonal
                if (quad.splitMode == TopLeftToBottomRight)
                {
                    buffmem->x = quad.position.d_right;
                    buffmem->y = quad.position.d_bottom;
                    buffmem->z = quad.z;
                    buffmem->diffuse = quad.topRightCol;
                    buffmem->tu1 = quad.texPosition.d_right;
                    buffmem->tv1 = quad.texPosition.d_bottom;
                }
                // bottom-left to top-right diagonal
                else
                {
                    buffmem->x = quad.position.d_right;
                    buffmem->y = quad.position.d_top;
                    buffmem->z = quad.z;
                    buffmem->diffuse = quad.bottomRightCol;
                    buffmem->tu1 = quad.texPosition.d_right;
                    buffmem->tv1 = quad.texPosition.d_top;
                }
                ++buffmem;
    
                // setup Vertex 3...
                buffmem->x = quad.position.d_left;
                buffmem->y = quad.position.d_top;
                buffmem->z = quad.z;
                buffmem->diffuse = quad.bottomLeftCol;
                buffmem->tu1 = quad.texPosition.d_left;
                buffmem->tv1 = quad.texPosition.d_top;
                ++buffmem;
    
                // setup Vertex 4...
                buffmem->x = quad.position.d_right;
                buffmem->y = quad.position.d_bottom;
                buffmem->z = quad.z;
                buffmem->diffuse = quad.topRightCol;
                buffmem->tu1 = quad.texPosition.d_right;
                buffmem->tv1 = quad.texPosition.d_bottom;
                ++buffmem;
    
                // setup Vertex 5...
                buffmem->x = quad.position.d_right;
                buffmem->y = quad.position.d_top;
                buffmem->z = quad.z;
                buffmem->diffuse = quad.bottomRightCol;
                buffmem->tu1 = quad.texPosition.d_right;
                buffmem->tv1 = quad.texPosition.d_top;
                ++buffmem;
    
                // setup Vertex 6...
                
                // top-left to bottom-right diagonal
                if (quad.splitMode == TopLeftToBottomRight)
                {
                    buffmem->x = quad.position.d_left;
                    buffmem->y = quad.position.d_top;
                    buffmem->z = quad.z;
                    buffmem->diffuse = quad.bottomLeftCol;
                    buffmem->tu1 = quad.texPosition.d_left;
                    buffmem->tv1 = quad.texPosition.d_top;
                }
                // bottom-left to top-right diagonal
                else
                {
                    buffmem->x = quad.position.d_left;
                    buffmem->y = quad.position.d_bottom;
                    buffmem->z = quad.z;
                    buffmem->diffuse = quad.topLeftCol;
                    buffmem->tu1 = quad.texPosition.d_left;
                    buffmem->tv1 = quad.texPosition.d_bottom;
                }
                ++buffmem;
            }
    
            // ensure we leave the buffer in the unlocked state
            d_buffer->unlock();
        }
        
        /// Render the buffer
        d_bufferPos = 0;
                bool first = true;

        // Iterate over each quad in the list and render it
        QuadList::iterator i = d_quadlist.begin();
        while(i != d_quadlist.end())
        {
            
            d_currTexture = i->texture;
            d_render_op.vertexData->vertexStart = d_bufferPos;
            for (; i != d_quadlist.end(); ++i)
            {
                const QuadInfo& quad = (*i);
                if (d_currTexture != quad.texture)
                                {
                    /// If it has a different texture, render this quad in next operation
                                        /// also need to reset render states
                                        first = true;
                            break;
                                }
                d_bufferPos += VERTEX_PER_QUAD;
            }
            d_render_op.vertexData->vertexCount = d_bufferPos - d_render_op.vertexData->vertexStart;
            /// Set texture, and do the render
            d_render_sys->_setTexture(0, true, d_currTexture);
                        if (first)
                        {
                                initRenderStates();
                                first = false;
                        }
            d_render_sys->_render(d_render_op);
        }

        }
    /// Count frames to check if utilization of vertex buffer was below half the capacity for 500,000 frames
    if(d_bufferPos < d_buffer->getNumVertices()/2)
       d_underused_framecount++;
    else
       d_underused_framecount = 0;
}


/*************************************************************************
        clear the queue
*************************************************************************/
void OgreCEGUIRenderer::clearRenderList(void)
{
        d_sorted = true;
        d_quadlist.clear();
}


/*************************************************************************
        create an empty texture
*************************************************************************/
Texture* OgreCEGUIRenderer::createTexture(void)
{
        OgreCEGUITexture* tex = new OgreCEGUITexture(this);
        d_texturelist.push_back(tex);
        return tex;
}


/*************************************************************************
        create a texture and load it with the specified file.
*************************************************************************/
Texture* OgreCEGUIRenderer::createTexture(const String& filename, const String& resourceGroup)
{
        OgreCEGUITexture* tex = (OgreCEGUITexture*)createTexture();
        tex->loadFromFile(filename, resourceGroup);

        return tex;
}


/*************************************************************************
        create a texture and set it to the specified size
*************************************************************************/
Texture* OgreCEGUIRenderer::createTexture(float size)
{
        OgreCEGUITexture* tex = (OgreCEGUITexture*)createTexture();
        tex->setOgreTextureSize((uint)size);

        return tex;
}


/*************************************************************************
        destroy the given texture
*************************************************************************/
void OgreCEGUIRenderer::destroyTexture(Texture* texture)
{
        if (texture != NULL)
        {
                OgreCEGUITexture* tex = (OgreCEGUITexture*)texture;

                d_texturelist.remove(tex);
                delete tex;
        }
}


/*************************************************************************
        destroy all textures still active
*************************************************************************/
void OgreCEGUIRenderer::destroyAllTextures(void)
{
        while (!d_texturelist.empty())
        {
                destroyTexture(*(d_texturelist.begin()));
        }
}


/*************************************************************************
        setup states etc        
*************************************************************************/
void OgreCEGUIRenderer::initRenderStates(void)
{
        using namespace Ogre;

        // set-up matrices
        d_render_sys->_setWorldMatrix(Matrix4::IDENTITY);
        d_render_sys->_setViewMatrix(Matrix4::IDENTITY);
        d_render_sys->_setProjectionMatrix(Matrix4::IDENTITY);

        // initialise render settings
        d_render_sys->setLightingEnabled(false);
        d_render_sys->_setDepthBufferParams(false, false);
        d_render_sys->_setDepthBias(0, 0);
        d_render_sys->_setCullingMode(CULL_NONE);
        d_render_sys->_setFog(FOG_NONE);
        d_render_sys->_setColourBufferWriteEnabled(true, true, true, true);
        d_render_sys->unbindGpuProgram(GPT_FRAGMENT_PROGRAM);
        d_render_sys->unbindGpuProgram(GPT_VERTEX_PROGRAM);
        d_render_sys->setShadingType(SO_GOURAUD);
        d_render_sys->_setPolygonMode(PM_SOLID);

        // initialise texture settings
        d_render_sys->_setTextureCoordCalculation(0, TEXCALC_NONE);
        d_render_sys->_setTextureCoordSet(0, 0);
        d_render_sys->_setTextureUnitFiltering(0, FO_LINEAR, FO_LINEAR, FO_POINT);
        d_render_sys->_setTextureAddressingMode(0, d_uvwAddressMode);
        d_render_sys->_setTextureMatrix(0, Matrix4::IDENTITY);
        d_render_sys->_setAlphaRejectSettings(CMPF_ALWAYS_PASS, 0, false);
        d_render_sys->_setTextureBlendMode(0, d_colourBlendMode);
        d_render_sys->_setTextureBlendMode(0, d_alphaBlendMode);
        d_render_sys->_disableTextureUnitsFrom(1);

        // enable alpha blending
        d_render_sys->_setSceneBlending(SBF_SOURCE_ALPHA, SBF_ONE_MINUS_SOURCE_ALPHA);
}


 
/*************************************************************************
        sort quads list according to texture    
*************************************************************************/
void OgreCEGUIRenderer::sortQuads(void)
{
        if (!d_sorted)
        {
                d_sorted = true;
        }

}

/*************************************************************************
render a quad directly to the display
*************************************************************************/
void OgreCEGUIRenderer::renderQuadDirect(const Rect& dest_rect, float z, const Texture* tex, const Rect& texture_rect, const ColourRect& colours, QuadSplitMode quad_split_mode)
{
        if (d_render_sys->_getViewport()->getOverlaysEnabled())
        {
                z = -1 + z;

                Rect final_rect;

                // set quad position, flipping y co-ordinates, and applying appropriate texel origin offset
                final_rect.d_left       = dest_rect.d_left;
                final_rect.d_right      = dest_rect.d_right;
                final_rect.d_top        = d_display_area.getHeight() - dest_rect.d_top;
                final_rect.d_bottom     = d_display_area.getHeight() - dest_rect.d_bottom;
                final_rect.offset(d_texelOffset);

                // convert quad co-ordinates for a -1 to 1 co-ordinate system.
                final_rect.d_left       /= (d_display_area.getWidth() * 0.5f);
                final_rect.d_right      /= (d_display_area.getWidth() * 0.5f);
                final_rect.d_top        /= (d_display_area.getHeight() * 0.5f);
                final_rect.d_bottom     /= (d_display_area.getHeight() * 0.5f);
                final_rect.offset(Point(-1.0f, -1.0f));

                // convert colours for ogre, note that top / bottom are switched.
        uint32 topLeftCol       = colourToOgre(colours.d_bottom_left);
        uint32 topRightCol      = colourToOgre(colours.d_bottom_right);
        uint32 bottomLeftCol    = colourToOgre(colours.d_top_left);
        uint32 bottomRightCol= colourToOgre(colours.d_top_right);

                QuadVertex*     buffmem = (QuadVertex*)d_direct_buffer->lock(Ogre::HardwareVertexBuffer::HBL_DISCARD);

                // setup Vertex 1...
                buffmem->x      = final_rect.d_left;
                buffmem->y      = final_rect. d_bottom;
                buffmem->z      = z;
                buffmem->diffuse = topLeftCol;
                buffmem->tu1    = texture_rect.d_left;
                buffmem->tv1    = texture_rect.d_bottom;
                ++buffmem;

                // setup Vertex 2...
                
                // top-left to bottom-right diagonal
                if (quad_split_mode == TopLeftToBottomRight)
                {
                        buffmem->x      = final_rect.d_right;
                        buffmem->y = final_rect.d_bottom;
                        buffmem->z      = z;
                        buffmem->diffuse = topRightCol;
                        buffmem->tu1    = texture_rect.d_right;
                        buffmem->tv1    = texture_rect.d_bottom;
                        ++buffmem;
                }
                // bottom-left to top-right diagonal
                else
                {
                        buffmem->x      = final_rect.d_right;
                        buffmem->y = final_rect.d_top;
                        buffmem->z      = z;
                        buffmem->diffuse = bottomRightCol;
                        buffmem->tu1    = texture_rect.d_right;
                        buffmem->tv1    = texture_rect.d_top;
                        ++buffmem;
                }

                // setup Vertex 3...
                buffmem->x      = final_rect.d_left;
                buffmem->y      = final_rect.d_top;
                buffmem->z      = z;
                buffmem->diffuse = bottomLeftCol;
                buffmem->tu1    = texture_rect.d_left;
                buffmem->tv1    = texture_rect.d_top;
                ++buffmem;

                // setup Vertex 4...
                buffmem->x      = final_rect.d_right;
                buffmem->y      = final_rect.d_bottom;
                buffmem->z      = z;
                buffmem->diffuse = topRightCol;
                buffmem->tu1    = texture_rect.d_right;
                buffmem->tv1    = texture_rect.d_bottom;
                ++buffmem;

                // setup Vertex 5...
                buffmem->x      = final_rect.d_right;
                buffmem->y      = final_rect.d_top;
                buffmem->z      = z;
                buffmem->diffuse = bottomRightCol;
                buffmem->tu1    = texture_rect.d_right;
                buffmem->tv1    = texture_rect.d_top;
                ++buffmem;

                // setup Vertex 6...
                
                // top-left to bottom-right diagonal
                if (quad_split_mode == TopLeftToBottomRight)
                {
                        buffmem->x      = final_rect.d_left;
                        buffmem->y = final_rect.d_top;
                        buffmem->z      = z;
                        buffmem->diffuse = bottomLeftCol;
                        buffmem->tu1    = texture_rect.d_left;
                        buffmem->tv1    = texture_rect.d_top;
                }
                // bottom-left to top-right diagonal
                else
                {
                        buffmem->x      = final_rect.d_left;
                        buffmem->y = final_rect.d_bottom;
                        buffmem->z      = z;
                        buffmem->diffuse = topLeftCol;
                        buffmem->tu1    = texture_rect.d_left;
                        buffmem->tv1    = texture_rect.d_bottom;
                }

                d_direct_buffer->unlock();

        //
                // perform rendering...
                //
                d_render_sys->_setTexture(0, true, ((OgreCEGUITexture*)tex)->getOgreTexture()->getName());
                initRenderStates();
                d_direct_render_op.vertexData->vertexCount = VERTEX_PER_QUAD;
                d_render_sys->_render(d_direct_render_op);
        }

}

/*************************************************************************
        convert ARGB colour value to whatever the Ogre render system is
        expecting.      
*************************************************************************/
uint32 OgreCEGUIRenderer::colourToOgre(const colour& col) const
{
        Ogre::ColourValue cv(col.getRed(), col.getGreen(), col.getBlue(), col.getAlpha());

    uint32 final;
        d_render_sys->convertColourValue(cv, &final);

        return final;
}


/*************************************************************************
        Set the scene manager to be used for rendering the GUI. 
*************************************************************************/
void OgreCEGUIRenderer::setTargetSceneManager(Ogre::SceneManager* scene_manager)
{
        // unhook from current scene manager.
        if (d_sceneMngr != NULL)
        {
                d_sceneMngr->removeRenderQueueListener(d_ourlistener);
                d_sceneMngr = NULL;
        }

        // hook new scene manager if that is not NULL
        if (scene_manager != NULL)
        {
                d_sceneMngr = scene_manager;
                d_sceneMngr->addRenderQueueListener(d_ourlistener);
        }

}


/*************************************************************************
        Set the target render queue for GUI rendering.  
*************************************************************************/
void OgreCEGUIRenderer::setTargetRenderQueue(Ogre::uint8 queue_id, bool post_queue)
{
        d_queue_id              = queue_id;
        d_post_queue    = post_queue;

        if (d_ourlistener != NULL)
        {
                d_ourlistener->setTargetRenderQueue(queue_id);
                d_ourlistener->setPostRenderQueue(post_queue);
        }

}


/*************************************************************************
        perform main work of the constructor
*************************************************************************/
void OgreCEGUIRenderer::constructor_impl(Ogre::RenderWindow* window, Ogre::uint8 queue_id, bool post_queue, uint max_quads)
{
        using namespace Ogre;

        // initialise the renderer fields
        d_queueing              = true;
        d_queue_id              = queue_id;
        d_currTexture.isNull();
        d_post_queue    = post_queue;
        d_sceneMngr             = NULL;
        d_bufferPos             = 0;
        d_sorted                = true;
        d_ogre_root             = Root::getSingletonPtr();
        d_render_sys    = d_ogre_root->getRenderSystem();
    // set ID string
    d_identifierString = "CEGUI::OgreRenderer - Official Ogre based renderer module for CEGUI";

        // Create and initialise the Ogre specific parts required for use in rendering later.
    // Main GUI
    createQuadRenderOp(d_render_op, d_buffer, VERTEXBUFFER_INITIAL_CAPACITY);
    d_underused_framecount = 0;

    // Mouse cursor
    createQuadRenderOp(d_direct_render_op, d_direct_buffer, VERTEX_PER_QUAD);

        // Discover display settings and setup d_display_area
        d_display_area.d_left   = 0;
        d_display_area.d_top    = 0;
        d_display_area.d_right  = window->getWidth();
        d_display_area.d_bottom = window->getHeight();

        // initialise required texel offset
        d_texelOffset = Point((float)d_render_sys->getHorizontalTexelOffset(), -(float)d_render_sys->getVerticalTexelOffset());

        // create listener which will handler the rendering side of things for us.
        d_ourlistener = new CEGUIRQListener(this, queue_id, post_queue);

        // Initialise blending modes to be used.
        d_colourBlendMode.blendType     = Ogre::LBT_COLOUR;
        d_colourBlendMode.source1       = Ogre::LBS_TEXTURE;
        d_colourBlendMode.source2       = Ogre::LBS_DIFFUSE;
        d_colourBlendMode.operation     = Ogre::LBX_MODULATE;

        d_alphaBlendMode.blendType      = Ogre::LBT_ALPHA;
        d_alphaBlendMode.source1        = Ogre::LBS_TEXTURE;
        d_alphaBlendMode.source2        = Ogre::LBS_DIFFUSE;
        d_alphaBlendMode.operation      = Ogre::LBX_MODULATE;

        d_uvwAddressMode.u = Ogre::TextureUnitState::TAM_CLAMP;
        d_uvwAddressMode.v = Ogre::TextureUnitState::TAM_CLAMP;
        d_uvwAddressMode.w = Ogre::TextureUnitState::TAM_CLAMP;
}


/*************************************************************************
        Create a texture from an existing Ogre::TexturePtr object       
*************************************************************************/
Texture* OgreCEGUIRenderer::createTexture(Ogre::TexturePtr& texture)
{
        OgreCEGUITexture* t = (OgreCEGUITexture*)createTexture();

        if (!texture.isNull())
        {
                t->setOgreTexture(texture);
        }

        return t;

}

/*************************************************************************
        Create a resource provider object
*************************************************************************/
ResourceProvider* OgreCEGUIRenderer::createResourceProvider(void)
{
    d_resourceProvider = new OgreCEGUIResourceProvider();
    return d_resourceProvider;
}

/*************************************************************************
Set the size of the display in pixels.  
*************************************************************************/
void OgreCEGUIRenderer::setDisplaySize(const Size& sz)
{
        if (d_display_area.getSize() != sz)
        {
                d_display_area.setSize(sz);

                EventArgs args;
                fireEvent(EventDisplaySizeChanged, args, EventNamespace);
        }

}

/*************************************************************************
        Callback from Ogre invoked before other stuff in our target queue
        is rendered
*************************************************************************/
void CEGUIRQListener::renderQueueStarted(Ogre::uint8 id, const Ogre::String& invocation, 
                                                                                 bool& skipThisQueue)
{
        if ((!d_post_queue) && (d_queue_id == id))
        {
                CEGUI::System::getSingleton().renderGUI();
        }

}


/*************************************************************************
Callback from Ogre invoked after other stuff in our target queue
is rendered
*************************************************************************/
void CEGUIRQListener::renderQueueEnded(Ogre::uint8 id, const Ogre::String& invocation, bool& repeatThisQueue)
{
        if ((d_post_queue) && (d_queue_id == id))
        {
                CEGUI::System::getSingleton().renderGUI();
        }

}

} // End of  CEGUI namespace section