OgreHardwareBuffer.h

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

Copyright (c) 2000-2012 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.
-----------------------------------------------------------------------------
*/
#ifndef __HardwareBuffer__
#define __HardwareBuffer__

// Precompiler options
#include "OgrePrerequisites.h"
#include "OgreException.h"

namespace Ogre {

    class _OgreExport HardwareBuffer : public BufferAlloc
    {

        public:
            enum Usage 
            {
                HBU_STATIC = 1,
                HBU_DYNAMIC = 2,
                HBU_WRITE_ONLY = 4,
                HBU_DISCARDABLE = 8,
                HBU_STATIC_WRITE_ONLY = 5, 
                HBU_DYNAMIC_WRITE_ONLY = 6,
                HBU_DYNAMIC_WRITE_ONLY_DISCARDABLE = 14


            };
            enum LockOptions
            {
                HBL_NORMAL,
                HBL_DISCARD,
                HBL_READ_ONLY,
                HBL_NO_OVERWRITE
                
            };
        protected:
            size_t mSizeInBytes;
            Usage mUsage;
            bool mIsLocked;
            size_t mLockStart;
            size_t mLockSize;
            bool mSystemMemory;
            bool mUseShadowBuffer;
            HardwareBuffer* mShadowBuffer;
            bool mShadowUpdated;
            bool mSuppressHardwareUpdate;
            
            virtual void* lockImpl(size_t offset, size_t length, LockOptions options) = 0;
            virtual void unlockImpl(void) = 0;

    public:
            HardwareBuffer(Usage usage, bool systemMemory, bool useShadowBuffer) 
                : mUsage(usage), mIsLocked(false), mSystemMemory(systemMemory), 
                mUseShadowBuffer(useShadowBuffer), mShadowBuffer(NULL), mShadowUpdated(false), 
                mSuppressHardwareUpdate(false) 
            {
                // If use shadow buffer, upgrade to WRITE_ONLY on hardware side
                if (useShadowBuffer && usage == HBU_DYNAMIC)
                {
                    mUsage = HBU_DYNAMIC_WRITE_ONLY;
                }
                else if (useShadowBuffer && usage == HBU_STATIC)
                {
                    mUsage = HBU_STATIC_WRITE_ONLY;
                }
            }
            virtual ~HardwareBuffer() {}
            virtual void* lock(size_t offset, size_t length, LockOptions options)
            {
                assert(!isLocked() && "Cannot lock this buffer, it is already locked!");

                void* ret = NULL;
                if ((length + offset) > mSizeInBytes)
                {
                    OGRE_EXCEPT(Exception::ERR_INVALIDPARAMS,
                        "Lock request out of bounds.",
                        "HardwareBuffer::lock");
                }
                else if (mUseShadowBuffer)
                {
                    if (options != HBL_READ_ONLY)
                    {
                        // we have to assume a read / write lock so we use the shadow buffer
                        // and tag for sync on unlock()
                        mShadowUpdated = true;
                    }

                    ret = mShadowBuffer->lock(offset, length, options);
                }
                else
                {
                    // Lock the real buffer if there is no shadow buffer 
                    ret = lockImpl(offset, length, options);
                    mIsLocked = true;
                }
                mLockStart = offset;
                mLockSize = length;
                return ret;
            }

            void* lock(LockOptions options)
            {
                return this->lock(0, mSizeInBytes, options);
            }
            virtual void unlock(void)
            {
                assert(isLocked() && "Cannot unlock this buffer, it is not locked!");

                // If we used the shadow buffer this time...
                if (mUseShadowBuffer && mShadowBuffer->isLocked())
                {
                    mShadowBuffer->unlock();
                    // Potentially update the 'real' buffer from the shadow buffer
                    _updateFromShadow();
                }
                else
                {
                    // Otherwise, unlock the real one
                    unlockImpl();
                    mIsLocked = false;
                }

            }

            virtual void readData(size_t offset, size_t length, void* pDest) = 0;
            virtual void writeData(size_t offset, size_t length, const void* pSource,
                    bool discardWholeBuffer = false) = 0;

            virtual void copyData(HardwareBuffer& srcBuffer, size_t srcOffset, 
                size_t dstOffset, size_t length, bool discardWholeBuffer = false)
            {
                const void *srcData = srcBuffer.lock(
                    srcOffset, length, HBL_READ_ONLY);
                this->writeData(dstOffset, length, srcData, discardWholeBuffer);
                srcBuffer.unlock();
            }

            virtual void copyData(HardwareBuffer& srcBuffer)
            {
                size_t sz = std::min(getSizeInBytes(), srcBuffer.getSizeInBytes()); 
                copyData(srcBuffer, 0, 0, sz, true);
            }
            
            virtual void _updateFromShadow(void)
            {
                if (mUseShadowBuffer && mShadowUpdated && !mSuppressHardwareUpdate)
                {
                    // Do this manually to avoid locking problems
                    const void *srcData = mShadowBuffer->lockImpl(
                        mLockStart, mLockSize, HBL_READ_ONLY);
                    // Lock with discard if the whole buffer was locked, otherwise normal
                    LockOptions lockOpt;
                    if (mLockStart == 0 && mLockSize == mSizeInBytes)
                        lockOpt = HBL_DISCARD;
                    else
                        lockOpt = HBL_NORMAL;
                    
                    void *destData = this->lockImpl(
                        mLockStart, mLockSize, lockOpt);
                    // Copy shadow to real
                    memcpy(destData, srcData, mLockSize);
                    this->unlockImpl();
                    mShadowBuffer->unlockImpl();
                    mShadowUpdated = false;
                }
            }

            size_t getSizeInBytes(void) const { return mSizeInBytes; }
            Usage getUsage(void) const { return mUsage; }
            bool isSystemMemory(void) const { return mSystemMemory; }
            bool hasShadowBuffer(void) const { return mUseShadowBuffer; }
            bool isLocked(void) const { 
                return mIsLocked || (mUseShadowBuffer && mShadowBuffer->isLocked()); 
            }
            void suppressHardwareUpdate(bool suppress) {
                mSuppressHardwareUpdate = suppress;
                if (!suppress)
                    _updateFromShadow();
            }




            
    };
}
#endif