source: downloads/Samples/VolumeTex/src/VolumeRenderable.cpp @ 5

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

Copyright (c) 2000-2006 Torus Knot Software Ltd
Also see acknowledgements in Readme.html

You may use this sample code for anything you like, it is not covered by the
LGPL like the rest of the engine.
-----------------------------------------------------------------------------
*/
#include "VolumeRenderable.h"
#include <OgreCamera.h>
#include <OgreSceneNode.h>
#include <OgreHardwareVertexBuffer.h>
#include <OgreHardwareIndexBuffer.h>
#include <OgreHardwareBufferManager.h>
#include <OgreMaterial.h>
#include <OgreTechnique.h>
#include <OgrePass.h>
#include <OgreTextureUnitState.h>
#include <OgreTextureManager.h>
#include <OgreMaterialManager.h>
using namespace Ogre;

VolumeRenderable::VolumeRenderable(size_t nSlices, float size, const String &texture):
        mSlices(nSlices),
        mSize(size),
        mTexture(texture)
{
        mRadius = sqrtf(size*size+size*size+size*size)/2.0f;
        mBox = Ogre::AxisAlignedBox(-size, -size, -size, size, size, size);
        
        // No shadows
        setCastShadows(false);
        
        initialise();
}
VolumeRenderable::~VolumeRenderable()
{
        // Remove private material
        MaterialManager::getSingleton().remove(mTexture);
    // need to release IndexData and vertexData created for renderable
    delete mRenderOp.indexData;
    delete mRenderOp.vertexData;

}

void VolumeRenderable::_notifyCurrentCamera( Camera* cam )
{
        MovableObject::_notifyCurrentCamera(cam);

        // Fake orientation toward camera
        Vector3 zVec = getParentNode()->_getDerivedPosition() - cam->getDerivedPosition();
        zVec.normalise();
        Vector3 fixedAxis = cam->getDerivedOrientation() * Vector3::UNIT_Y ;
        
        Vector3 xVec = fixedAxis.crossProduct( zVec );
        xVec.normalise();

        Vector3 yVec = zVec.crossProduct( xVec );
        yVec.normalise();
        
        Quaternion oriQuat;
        oriQuat.FromAxes( xVec, yVec, zVec );
        
        oriQuat.ToRotationMatrix(mFakeOrientation);
        
        Matrix3 tempMat;
        Quaternion q = getParentNode()->_getDerivedOrientation().UnitInverse() * oriQuat ;
        q.ToRotationMatrix(tempMat);
        
        Matrix4 rotMat = Matrix4::IDENTITY;
        rotMat = tempMat;
        rotMat.setTrans(Vector3(0.5f, 0.5f, 0.5f));
        mUnit->setTextureTransform(rotMat);
}


//const Ogre::Quaternion& VolumeRenderable::getWorldOrientation(void) const
//{
//      return Ogre::Quaternion::IDENTITY;
//}

void VolumeRenderable::getWorldTransforms( Matrix4* xform ) const
{
        Matrix4 destMatrix(Matrix4::IDENTITY); // this initialisation is needed
        
        const Vector3 &position = getParentNode()->_getDerivedPosition();
        const Vector3 &scale = getParentNode()->_getDerivedScale();
        Matrix3 scale3x3(Matrix3::ZERO);
        scale3x3[0][0] = scale.x;
        scale3x3[1][1] = scale.y;
        scale3x3[2][2] = scale.z;

        destMatrix = mFakeOrientation * scale3x3;
        destMatrix.setTrans(position);
                
        *xform = destMatrix;
}

void VolumeRenderable::initialise()
{
        // Create geometry
        size_t nvertices = mSlices*4; // n+1 planes
        size_t elemsize = 3*3;
        size_t dsize = elemsize*nvertices;
        size_t x;
        
        Ogre::IndexData *idata = new Ogre::IndexData();
        Ogre::VertexData *vdata = new Ogre::VertexData();
        
        // Create  structures
        float *vertices = new float[dsize];
        
        float coords[4][2] = {
                {0.0f, 0.0f},
                {0.0f, 1.0f},
                {1.0f, 0.0f},
                {1.0f, 1.0f}
        };
        for(x=0; x<mSlices; x++) 
        {
                for(size_t y=0; y<4; y++)
                {
                        float xcoord = coords[y][0]-0.5;
                        float ycoord = coords[y][1]-0.5;
                        float zcoord = -((float)x/(float)(mSlices-1)  - 0.5f);
                        // 1.0f .. a/(a+1)
                        // coordinate
                        vertices[x*4*elemsize+y*elemsize+0] = xcoord*(mSize/2.0f);
                        vertices[x*4*elemsize+y*elemsize+1] = ycoord*(mSize/2.0f);
                        vertices[x*4*elemsize+y*elemsize+2] = zcoord*(mSize/2.0f);
                        // normal
                        vertices[x*4*elemsize+y*elemsize+3] = 0.0f;
                        vertices[x*4*elemsize+y*elemsize+4] = 0.0f;
                        vertices[x*4*elemsize+y*elemsize+5] = 1.0f;
                        // tex
                        vertices[x*4*elemsize+y*elemsize+6] = xcoord*sqrtf(3.0f);
                        vertices[x*4*elemsize+y*elemsize+7] = ycoord*sqrtf(3.0f);
                        vertices[x*4*elemsize+y*elemsize+8] = zcoord*sqrtf(3.0f);
                } 
        }
        unsigned short *faces = new unsigned short[mSlices*6];
        for(x=0; x<mSlices; x++) 
        {
                faces[x*6+0] = x*4+0;
                faces[x*6+1] = x*4+1;
                faces[x*6+2] = x*4+2;
                faces[x*6+3] = x*4+1;
                faces[x*6+4] = x*4+2;
                faces[x*6+5] = x*4+3;
        }
        // Setup buffers
        vdata->vertexStart = 0;
        vdata->vertexCount = nvertices;
        
        VertexDeclaration* decl = vdata->vertexDeclaration;
        VertexBufferBinding* bind = vdata->vertexBufferBinding;

        size_t offset = 0;
        decl->addElement(0, offset, VET_FLOAT3, VES_POSITION);
        offset += VertexElement::getTypeSize(VET_FLOAT3);
        decl->addElement(0, offset, VET_FLOAT3, VES_NORMAL);
        offset += VertexElement::getTypeSize(VET_FLOAT3);
        decl->addElement(0, offset, VET_FLOAT3, VES_TEXTURE_COORDINATES);
        offset += VertexElement::getTypeSize(VET_FLOAT3);

        HardwareVertexBufferSharedPtr vbuf = 
        HardwareBufferManager::getSingleton().createVertexBuffer(
                offset, nvertices, HardwareBuffer::HBU_STATIC_WRITE_ONLY);

        bind->setBinding(0, vbuf);

        vbuf->writeData(0, vbuf->getSizeInBytes(), vertices, true);
        
        HardwareIndexBufferSharedPtr ibuf = HardwareBufferManager::getSingleton().
                createIndexBuffer(
                        HardwareIndexBuffer::IT_16BIT, 
                        mSlices*6, 
                        HardwareBuffer::HBU_STATIC_WRITE_ONLY);

        idata->indexBuffer = ibuf;
        idata->indexCount = mSlices*6;
        idata->indexStart = 0;
        ibuf->writeData(0, ibuf->getSizeInBytes(), faces, true);

        // Delete temporary buffers
        delete [] vertices;
        delete [] faces;
        
        // Now make the render operation
        mRenderOp.operationType = Ogre::RenderOperation::OT_TRIANGLE_LIST;
        mRenderOp.indexData = idata;
        mRenderOp.vertexData = vdata;
        mRenderOp.useIndexes = true;
        
         // Create a brand new private material
        MaterialPtr material = 
                MaterialManager::getSingleton().create(mTexture, "VolumeRenderable",
                        false, 0); // Manual, loader

        // Remove pre-created technique from defaults
        material->removeAllTechniques();
        
        // Create a techinique and a pass and a texture unit
        Technique * technique = material->createTechnique();
        Pass * pass = technique->createPass();
        TextureUnitState * textureUnit = pass->createTextureUnitState();
        
        // Set pass parameters
        pass->setSceneBlending(SBT_TRANSPARENT_ALPHA);
        pass->setDepthWriteEnabled(false);
        pass->setCullingMode(CULL_NONE);
        pass->setLightingEnabled(false);
        
        // Set texture unit parameters
        textureUnit->setTextureAddressingMode(TextureUnitState::TAM_CLAMP);
        textureUnit->setTextureName(mTexture, TEX_TYPE_3D);
        textureUnit->setTextureFiltering(TFO_TRILINEAR);
        
        mUnit = textureUnit;
        m_pMaterial = material;
}

Ogre::Real VolumeRenderable::getBoundingRadius() const
{
        return mRadius;
}
Ogre::Real VolumeRenderable::getSquaredViewDepth(const Ogre::Camera* cam) const
{
        Ogre::Vector3 min, max, mid, dist;

        min = mBox.getMinimum();
        max = mBox.getMaximum();
        mid = ((min - max) * 0.5) + min;
        dist = cam->getDerivedPosition() - mid;
                                                                        
        return dist.squaredLength();
}