Extracted adaptive step size and empty space skipping from SimpleRaycaster to OptimizedRaycaster

modules/vis/glsl/optimizedraycaster.frag

+// ================================================================================================
+// 
+// This file is part of the CAMPVis Software Framework.
+// 
+// If not explicitly stated otherwise: Copyright (C) 2012, all rights reserved,
+//      Christian Schulte zu Berge <christian.szb@in.tum.de>
+//      Chair for Computer Aided Medical Procedures
+//      Technische Universitt Mnchen
+//      Boltzmannstr. 3, 85748 Garching b. Mnchen, Germany
+// For a full list of authors and contributors, please refer to the file "AUTHORS.txt".
+// 
+// The licensing of this softare is not yet resolved. Until then, redistribution in source or
+// binary forms outside the CAMP chair is not permitted, unless explicitly stated in legal form.
+// However, the names of the original authors and the above copyright notice must retain in its
+// original state in any case.
+// 
+// Legal disclaimer provided by the BSD license:
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
+// IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY 
+// AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR 
+// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
+// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 
+// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 
+// OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+// POSSIBILITY OF SUCH DAMAGE.
+// 
+// ================================================================================================
+
+layout(location = 0) out vec4 out_Color;     ///< outgoing fragment color
+layout(location = 1) out vec4 out_FHP;       ///< outgoing fragment first hitpoint
+layout(location = 2) out vec4 out_FHN;       ///< outgoing fragment first hit normal
+
+#include "tools/gradient.frag"
+#include "tools/raycasting.frag"
+#include "tools/shading.frag"
+#include "tools/texture2d.frag"
+#include "tools/texture3d.frag"
+#include "tools/transferfunction.frag"
+
+uniform vec2 _viewportSizeRCP;
+uniform float _jitterStepSizeMultiplier;
+
+
+// ray entry points
+uniform sampler2D _entryPoints;
+uniform sampler2D _entryPointsDepth;
+uniform TextureParameters2D _entryParams;
+
+// ray exit points
+uniform sampler2D _exitPoints;
+uniform sampler2D _exitPointsDepth;
+uniform TextureParameters2D _exitParams;
+
+// DRR volume
+uniform sampler3D _volume;
+uniform TextureParameters3D _volumeTextureParams;
+
+// Transfer function
+uniform sampler1D _transferFunction;
+uniform TFParameters1D _transferFunctionParams;
+
+
+// BBV Lookup volume
+uniform usampler3D _bbvTexture;
+uniform TextureParameters3D _bbvTextureParams;
+uniform int _bbvBrickSize;
+uniform bool _hasBbv;
+
+
+uniform LightSource _lightSource;
+uniform vec3 _cameraPosition;
+
+uniform float _samplingStepSize;
+
+#ifdef ENABLE_ADAPTIVE_STEPSIZE
+bool _inVoid = false;
+#endif
+
+#ifdef ENABLE_SHADOWING
+uniform float _shadowIntensity;
+#endif
+
+const float positiveInfinity = 1.0 / 0.0;
+
+// TODO: copy+paste from Voreen - eliminate or improve.
+const float SAMPLING_BASE_INTERVAL_RCP = 200.0;
+
+ivec3 voxelToBrick(in vec3 voxel) {
+    return ivec3(floor(voxel / _bbvBrickSize));
+}
+
+// samplePosition is in texture coordiantes [0, 1]
+bool lookupInBbv(in vec3 samplePosition) {
+    ivec3 byte = voxelToBrick(samplePosition * _volumeTextureParams._size);
+    uint bit = uint(byte.x % 8);
+    byte.x /= 8;
+
+    uint texel = texelFetch(_bbvTexture, byte, 0).r;
+
+    return (texel & (1U << bit)) != 0U;
+}
+
+float rayBoxIntersection(in vec3 rayOrigin, in vec3 rayDirection, in vec3 box[2], in float t) {
+    vec3 rayInverseDirection = 1.f / rayDirection;
+    ivec3 raySign = ivec3(lessThan(rayDirection, vec3(0.0, 0.0, 0.0));
+
+    vec3 tMin = (box[raySign] - rayOrigin) / rayInverseDirection;
+    vec3 tMax = (box[1 - raySign] - rayOrigin) / rayInverseDirection;
+
+    tMin *= vec3(lessThan(tMin, vec3(t, t, t)) * positiveInfinity;
+    tMax *= vec3(lessThan(tMax, vec3(t, t, t)) * positiveInfinity;
+
+    return min(min(tMin.x, min(tMin.y, tMin.z))   ,    min(tMax.x, min(tMax.y, tMax.z)));
+}
+
+/**
+ * Performs the raycasting and returns the final fragment color.
+ */
+vec4 performRaycasting(in vec3 entryPoint, in vec3 exitPoint, in vec2 texCoords) {
+    vec4 result = vec4(0.0);
+    float firstHitT = -1.0;
+#ifdef ENABLE_ADAPTIVE_STEPSIZE
+    float samplingRateCompensationMultiplier = 1.0;
+#endif
+
+    // calculate ray parameters
+    vec3 direction = exitPoint.rgb - entryPoint.rgb;
+    float t = 0.0;
+    float tend = length(direction);
+    direction = normalize(direction);
+
+    jitterEntryPoint(entryPoint, direction, _samplingStepSize * _jitterStepSizeMultiplier);
+
+    while (t < tend) {
+        // compute sample position
+        vec3 samplePosition = entryPoint.rgb + t * direction;
+
+        if (_hasBbv) {
+            if (! lookupInBbv(samplePosition)) {
+
+                // advance to the next evaluation point along the ray
+                t += 4.0*_samplingStepSize;
+
+
+#ifdef ENABLE_ADAPTIVE_STEPSIZE
+                samplingRateCompensationMultiplier = 1.0;
+#endif
+            continue;
+            }
+        }
+
+        // lookup intensity and TF
+        float intensity = getElement3DNormalized(_volume, _volumeTextureParams, samplePosition).a;
+        vec4 color = lookupTF(_transferFunction, _transferFunctionParams, intensity);
+
+#ifdef ENABLE_ADAPTIVE_STEPSIZE
+        if (color.a <= 0.0) {
+            // we're within void, make the steps bigger
+            _inVoid = true;
+        }
+        else {
+            if (_inVoid) {
+                float formerT = t - _samplingStepSize;
+
+                // we just left the void, perform intersection refinement
+                for (float stepPower = 0.5; stepPower > 0.1; stepPower /= 2.0) {
+                    // compute refined sample position
+                    float newT = formerT + _samplingStepSize * stepPower;
+                    vec3 newSamplePosition = entryPoint.rgb + newT * direction;
+
+                    // lookup refined intensity + TF
+                    float newIntensity = getElement3DNormalized(_volume, _volumeTextureParams, newSamplePosition).a;
+                    vec4 newColor = lookupTF(_transferFunction, _transferFunctionParams, newIntensity);
+
+                    if (newColor.a <= 0.0) {
+                        // we're back in the void - look on the right-hand side
+                        formerT = newT;
+                    }
+                    else {
+                        // we're still in the matter - look on the left-hand side
+                        samplePosition = newSamplePosition;
+                        color = newColor;
+                        t -= _samplingStepSize * stepPower;
+                    }
+                }
+                _inVoid = false;
+            }
+        }
+#endif
+
+#ifdef ENABLE_SHADOWING
+        // simple and expensive implementation of hard shadows
+        if (color.a > 0.1) {
+            // compute direction from sample to light
+            vec3 L = normalize(_lightSource._position - textureToWorld(_volumeTextureParams, samplePosition).xyz) * _samplingStepSize;
+
+            bool finished = false;
+            vec3 position = samplePosition + L;
+            float shadowFactor = 0.0;
+
+            // traverse ray from sample to light
+            while (! finished) {
+                // grab intensity and TF opacity
+                intensity = getElement3DNormalized(_volume, _volumeTextureParams, position).a;
+                shadowFactor += lookupTF(_transferFunction, _transferFunctionParams, intensity).a;
+
+                position += L;
+                finished = (shadowFactor > 0.95)
+                         || any(lessThan(position, vec3(0.0, 0.0, 0.0)))
+                         || any(greaterThan(position, vec3(1.0, 1.0, 1.0)));
+            }
+            // apply shadow to color
+            color.rgb *= (1.0 - shadowFactor * _shadowIntensity);
+        }
+#endif
+
+        // perform compositing
+        if (color.a > 0.0) {
+#ifdef ENABLE_SHADING
+            // compute gradient (needed for shading and normals)
+            vec3 gradient = computeGradient(_volume, _volumeTextureParams, samplePosition);
+            color.rgb = calculatePhongShading(textureToWorld(_volumeTextureParams, samplePosition).xyz, _lightSource, _cameraPosition, gradient, color.rgb, color.rgb, vec3(1.0, 1.0, 1.0));
+#endif
+
+            // accomodate for variable sampling rates
+#ifdef ENABLE_ADAPTIVE_STEPSIZE
+            color.a = 1.0 - pow(1.0 - color.a, _samplingStepSize * samplingRateCompensationMultiplier * SAMPLING_BASE_INTERVAL_RCP);
+#else
+            color.a = 1.0 - pow(1.0 - color.a, _samplingStepSize * SAMPLING_BASE_INTERVAL_RCP);
+#endif
+            result.rgb = mix(color.rgb, result.rgb, result.a);
+            result.a = result.a + (1.0 -result.a) * color.a;
+        }
+
+        // save first hit ray parameter for depth value calculation
+        if (firstHitT < 0.0 && result.a > 0.0) {
+            firstHitT = t;
+            out_FHP = vec4(samplePosition, 1.0);
+            out_FHN = vec4(normalize(computeGradient(_volume, _volumeTextureParams, samplePosition)), 1.0);
+        }
+
+        // early ray termination
+        if (result.a > 0.975) {
+            result.a = 1.0;
+            t = tend;
+        }
+
+        // advance to the next evaluation point along the ray
+#ifdef ENABLE_ADAPTIVE_STEPSIZE
+        samplingRateCompensationMultiplier = (_inVoid ? 1.0 : 0.25);
+        t += _samplingStepSize * (_inVoid ? 1.0 : 0.125);
+        
+#else
+        t += _samplingStepSize;
+#endif
+    }
+
+    // calculate depth value from ray parameter
+    gl_FragDepth = 1.0;
+    if (firstHitT >= 0.0) {
+        float depthEntry = getElement2DNormalized(_entryPointsDepth, _entryParams, texCoords).z;
+        float depthExit = getElement2DNormalized(_exitPointsDepth, _exitParams, texCoords).z;
+        gl_FragDepth = calculateDepthValue(firstHitT/tend, depthEntry, depthExit);
+    }
+    return result;
+}
+
+/***
+ * The main method.
+ ***/
+void main() {
+    vec2 p = gl_FragCoord.xy * _viewportSizeRCP;
+    vec3 frontPos = getElement2DNormalized(_entryPoints, _entryParams, p).rgb;
+    vec3 backPos = getElement2DNormalized(_exitPoints, _exitParams, p).rgb;
+
+    //determine whether the ray has to be casted
+    if (frontPos == backPos) {
+        //background need no raycasting
+        discard;
+    } else {
+        //fragCoords are lying inside the boundingbox
+        out_Color = performRaycasting(frontPos, backPos, p);
+    }
+}

modules/vis/glsl/simpleraycaster.frag

@@ -61,22 +61,11 @@ uniform sampler1D _transferFunction;
 uniform TFParameters1D _transferFunctionParams;
 
 
-// BBV Lookup volume
-uniform usampler3D _bbvTexture;
-uniform TextureParameters3D _bbvTextureParams;
-uniform int _bbvBrickSize;
-uniform bool _hasBbv;
-
-
 uniform LightSource _lightSource;
 uniform vec3 _cameraPosition;
 
 uniform float _samplingStepSize;
 
-#ifdef ENABLE_ADAPTIVE_STEPSIZE
-bool _inVoid = false;
-#endif
-
 #ifdef ENABLE_SHADOWING
 uniform float _shadowIntensity;
 #endif
@@ -84,30 +73,12 @@ uniform float _shadowIntensity;
 // TODO: copy+paste from Voreen - eliminate or improve.
 const float SAMPLING_BASE_INTERVAL_RCP = 200.0;
 
-ivec3 voxelToBrick(in vec3 voxel) {
-    return ivec3(floor(voxel / _bbvBrickSize));
-}
-
-// samplePosition is in texture coordiantes [0, 1]
-bool lookupInBbv(in vec3 samplePosition) {
-    ivec3 byte = voxelToBrick(samplePosition * _volumeTextureParams._size);
-    uint bit = uint(byte.x % 8);
-    byte.x /= 8;
-
-    uint texel = texelFetch(_bbvTexture, byte, 0).r;
-
-    return (texel & (1U << bit)) != 0U;
-}
-
 /**
  * Performs the raycasting and returns the final fragment color.
  */
 vec4 performRaycasting(in vec3 entryPoint, in vec3 exitPoint, in vec2 texCoords) {
     vec4 result = vec4(0.0);
     float firstHitT = -1.0;
-#ifdef ENABLE_ADAPTIVE_STEPSIZE
-    float samplingRateCompensationMultiplier = 1.0;
-#endif
 
     // calculate ray parameters
     vec3 direction = exitPoint.rgb - entryPoint.rgb;
@@ -121,59 +92,10 @@ vec4 performRaycasting(in vec3 entryPoint, in vec3 exitPoint, in vec2 texCoords)
         // compute sample position
         vec3 samplePosition = entryPoint.rgb + t * direction;
 
-        if (_hasBbv) {
-            if (! lookupInBbv(samplePosition)) {
-
-                // advance to the next evaluation point along the ray
-                t += 4.0*_samplingStepSize;
-
-
-#ifdef ENABLE_ADAPTIVE_STEPSIZE
-                samplingRateCompensationMultiplier = 1.0;
-#endif
-            continue;
-            }
-        }
-
         // lookup intensity and TF
         float intensity = getElement3DNormalized(_volume, _volumeTextureParams, samplePosition).a;
         vec4 color = lookupTF(_transferFunction, _transferFunctionParams, intensity);
 
-#ifdef ENABLE_ADAPTIVE_STEPSIZE
-        if (color.a <= 0.0) {
-            // we're within void, make the steps bigger
-            _inVoid = true;
-        }
-        else {
-            if (_inVoid) {
-                float formerT = t - _samplingStepSize;
-
-                // we just left the void, perform intersection refinement
-                for (float stepPower = 0.5; stepPower > 0.1; stepPower /= 2.0) {
-                    // compute refined sample position
-                    float newT = formerT + _samplingStepSize * stepPower;
-                    vec3 newSamplePosition = entryPoint.rgb + newT * direction;
-
-                    // lookup refined intensity + TF
-                    float newIntensity = getElement3DNormalized(_volume, _volumeTextureParams, newSamplePosition).a;
-                    vec4 newColor = lookupTF(_transferFunction, _transferFunctionParams, newIntensity);
-
-                    if (newColor.a <= 0.0) {
-                        // we're back in the void - look on the right-hand side
-                        formerT = newT;
-                    }
-                    else {
-                        // we're still in the matter - look on the left-hand side
-                        samplePosition = newSamplePosition;
-                        color = newColor;
-                        t -= _samplingStepSize * stepPower;
-                    }
-                }
-                _inVoid = false;
-            }
-        }
-#endif
-
 #ifdef ENABLE_SHADOWING
         // simple and expensive implementation of hard shadows
         if (color.a > 0.1) {
@@ -209,11 +131,7 @@ vec4 performRaycasting(in vec3 entryPoint, in vec3 exitPoint, in vec2 texCoords)
 #endif
 
             // accomodate for variable sampling rates
-#ifdef ENABLE_ADAPTIVE_STEPSIZE
-            color.a = 1.0 - pow(1.0 - color.a, _samplingStepSize * samplingRateCompensationMultiplier * SAMPLING_BASE_INTERVAL_RCP);
-#else
             color.a = 1.0 - pow(1.0 - color.a, _samplingStepSize * SAMPLING_BASE_INTERVAL_RCP);
-#endif
             result.rgb = mix(color.rgb, result.rgb, result.a);
             result.a = result.a + (1.0 -result.a) * color.a;
         }
@@ -232,13 +150,7 @@ vec4 performRaycasting(in vec3 entryPoint, in vec3 exitPoint, in vec2 texCoords)
         }
 
         // advance to the next evaluation point along the ray
-#ifdef ENABLE_ADAPTIVE_STEPSIZE
-        samplingRateCompensationMultiplier = (_inVoid ? 1.0 : 0.25);
-        t += _samplingStepSize * (_inVoid ? 1.0 : 0.125);
-        
-#else
         t += _samplingStepSize;
-#endif
     }
 
     // calculate depth value from ray parameter

modules/vis/processors/optimizedraycaster.cpp

+// ================================================================================================
+// 
+// This file is part of the CAMPVis Software Framework.
+// 
+// If not explicitly stated otherwise: Copyright (C) 2012, all rights reserved,
+//      Christian Schulte zu Berge <christian.szb@in.tum.de>
+//      Chair for Computer Aided Medical Procedures
+//      Technische Universität München
+//      Boltzmannstr. 3, 85748 Garching b. München, Germany
+// For a full list of authors and contributors, please refer to the file "AUTHORS.txt".
+// 
+// The licensing of this softare is not yet resolved. Until then, redistribution in source or
+// binary forms outside the CAMP chair is not permitted, unless explicitly stated in legal form.
+// However, the names of the original authors and the above copyright notice must retain in its
+// original state in any case.
+// 
+// Legal disclaimer provided by the BSD license:
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
+// IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY 
+// AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR 
+// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
+// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 
+// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 
+// OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+// POSSIBILITY OF SUCH DAMAGE.
+// 
+// ================================================================================================
+
+#include "optimizedraycaster.h"
+
+#include "core/tools/quadrenderer.h"
+#include "core/datastructures/renderdata.h"
+#include "core/pipeline/processordecoratorshading.h"
+
+#include <tbb/tbb.h>
+
+namespace campvis {
+    const std::string OptimizedRaycaster::loggerCat_ = "CAMPVis.modules.vis.OptimizedRaycaster";
+
+    OptimizedRaycaster::OptimizedRaycaster(IVec2Property* viewportSizeProp)
+        : RaycastingProcessor(viewportSizeProp, "modules/vis/glsl/optimizedraycaster.frag", true)
+        , p_targetImageID("targetImageID", "Output Image", "", DataNameProperty::WRITE)
+        , p_enableShadowing("EnableShadowing", "Enable Hard Shadows (Expensive!)", false, AbstractProcessor::INVALID_RESULT | AbstractProcessor::INVALID_SHADER | AbstractProcessor::INVALID_PROPERTIES)
+        , p_shadowIntensity("ShadowIntensity", "Shadow Intensity", .5f, .0f, 1.f)
+        , p_enableAdaptiveStepsize("EnableAdaptiveStepSize", "Enable Adaptive Step Size", true, AbstractProcessor::INVALID_RESULT | AbstractProcessor::INVALID_SHADER)
+        , p_useEmptySpaceSkipping("EnableEmptySpaceSkipping", "Enable Empty Space Skipping", false, AbstractProcessor::INVALID_RESULT | INVALID_BBV)
+        , _bbv(0)
+        , _t(0)
+    {
+        addDecorator(new ProcessorDecoratorShading());
+
+        addProperty(&p_targetImageID);
+        addProperty(&p_enableAdaptiveStepsize);
+        addProperty(&p_useEmptySpaceSkipping);
+
+        addProperty(&p_enableShadowing);
+        addProperty(&p_shadowIntensity);
+        p_shadowIntensity.setVisible(false);
+
+//         p_transferFunction.setInvalidationLevel(p_transferFunction.getInvalidationLevel() | INVALID_BBV);
+//         p_sourceImageID.setInvalidationLevel(p_sourceImageID.getInvalidationLevel() | INVALID_BBV);
+
+        decoratePropertyCollection(this);
+    }
+
+    OptimizedRaycaster::~OptimizedRaycaster() {
+    }
+
+    void OptimizedRaycaster::init() {
+        RaycastingProcessor::init();
+    }
+
+    void OptimizedRaycaster::deinit() {
+        delete _bbv;
+        delete _t;
+        RaycastingProcessor::deinit();
+    }
+
+    void OptimizedRaycaster::processImpl(DataContainer& data, ImageRepresentationGL::ScopedRepresentation& image) {
+        tgt::TextureUnit bbvUnit;
+
+        if (getInvalidationLevel() & INVALID_BBV) {
+            DataHandle dh = DataHandle(const_cast<ImageData*>(image->getParent())); // HACK HACK HACK
+            generateBbv(dh);
+
+//             tgt::Texture* batman = _bbv->exportToImageData();
+//             ImageData* robin = new ImageData(3, batman->getDimensions(), 1);
+//             ImageRepresentationGL::create(robin, batman);
+//             data.addData("All glory to the HYPNOTOAD!", robin);
+
+            validate(INVALID_BBV);
+        }
+
+        if (_t != 0 && p_useEmptySpaceSkipping.getValue()) {
+            // bind
+            bbvUnit.activate();
+            _t->bind();
+            _shader->setIgnoreUniformLocationError(true);
+            _shader->setUniform("_bbvTexture", bbvUnit.getUnitNumber());
+            _shader->setUniform("_bbvTextureParams._size", tgt::vec3(_t->getDimensions()));
+            _shader->setUniform("_bbvTextureParams._sizeRCP", tgt::vec3(1.f) / tgt::vec3(_t->getDimensions()));
+            _shader->setUniform("_bbvTextureParams._numChannels", static_cast<int>(1));
+
+            _shader->setUniform("_bbvBrickSize", static_cast<int>(_bbv->getBrickSize()));
+            _shader->setUniform("_hasBbv", true);
+            _shader->setIgnoreUniformLocationError(false);
+        }
+        else {
+            _shader->setUniform("_hasBbv", false);
+        }
+
+        FramebufferActivationGuard fag(this);
+        createAndAttachTexture(GL_RGBA8);
+//         createAndAttachTexture(GL_RGBA32F);
+//         createAndAttachTexture(GL_RGBA32F);
+        createAndAttachDepthTexture();
+
+//         static const GLenum buffers[] = { GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1 , GL_COLOR_ATTACHMENT2 };
+//         glDrawBuffers(3, buffers);
+
+        if (p_enableShadowing.getValue())
+            _shader->setUniform("_shadowIntensity", p_shadowIntensity.getValue());
+
+        glEnable(GL_DEPTH_TEST);
+        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+        QuadRdr.renderQuad();
+        glDisable(GL_DEPTH_TEST);
+        LGL_ERROR;
+
+        data.addData(p_targetImageID.getValue(), new RenderData(_fbo));
+    }
+
+    std::string OptimizedRaycaster::generateHeader() const {
+        std::string toReturn = RaycastingProcessor::generateHeader();
+        if (p_enableShadowing.getValue())
+            toReturn += "#define ENABLE_SHADOWING\n";
+        if (p_enableAdaptiveStepsize.getValue())
+            toReturn += "#define ENABLE_ADAPTIVE_STEPSIZE\n";
+        return toReturn;
+    }
+
+    void OptimizedRaycaster::updateProperties() {
+        p_shadowIntensity.setVisible(p_enableShadowing.getValue());
+        validate(AbstractProcessor::INVALID_PROPERTIES);
+    }
+
+    void OptimizedRaycaster::generateBbv(DataHandle dh) {
+        delete _bbv;
+        _bbv = 0;
+        delete _t;
+        _t = 0;
+
+        if (dh.getData() == 0) {
+            return;
+        }
+        else {
+            if (const ImageData* id = dynamic_cast<const ImageData*>(dh.getData())) {
+                if (const ImageRepresentationLocal* rep = id->getRepresentation<ImageRepresentationLocal>(true)) {
+            	    _bbv = new BinaryBrickedVolume(rep->getParent(), 2);
+
+                    GLubyte* tfBuffer = p_transferFunction.getTF()->getTexture()->downloadTextureToBuffer(GL_RGBA, GL_UNSIGNED_BYTE);
+                    size_t tfNumElements = p_transferFunction.getTF()->getTexture()->getDimensions().x;
+
+                    LDEBUG("Start computing brick visibilities...");
+                    // parallelly traverse the bricks
+                    // have minimum group size 8 to avoid race conditions (every 8 neighbor bricks write to the same byte)!
+                    tbb::parallel_for(tbb::blocked_range<size_t>(0, _bbv->getNumBrickIndices(), 8), [&] (const tbb::blocked_range<size_t>& range) {
+                        const tgt::vec2& tfIntensityDomain = p_transferFunction.getTF()->getIntensityDomain();
+
+                        for (size_t i = range.begin(); i != range.end(); ++i) {
+                            // for each brick, get all corresponding voxels in the reference volume
+                            std::vector<tgt::svec3> voxels = _bbv->getAllVoxelsForBrick(i);
+
+                            // traverse the voxels to check whether their intensities are mapped to some opacity
+                            for (size_t v = 0; v < voxels.size(); ++v