Improved VolumeExplorer:

* Fixed orientation of XY-slice (flipped along Y axis)
* Implemented background for raycasting result
* Fixed sum for volume rendering integral evaluation in simpleraycaster.frag

core/glsl/tools/background.frag

@@ -26,6 +26,11 @@ uniform vec4 _backgroundColor1;
 uniform vec4 _backgroundColor2;
 
 void renderBackground(in vec2 texCoords, out vec4 outColor) {
-        outColor = mix(_backgroundColor1, _backgroundColor2, 0.5 * (texCoords.x + texCoords.y));
-        gl_FragDepth = 1.0;
+    outColor = mix(_backgroundColor1, _backgroundColor2, 0.5 * (texCoords.x + texCoords.y));
+    gl_FragDepth = 1.0;
+}
+
+vec4 blendBackground(in vec2 texCoords, in vec4 outColor) {
+    vec4 backgroundColor = mix(_backgroundColor1, _backgroundColor2, 0.5 * (texCoords.x + texCoords.y));
+    return vec4(mix(backgroundColor.rgb, outColor.rgb, outColor.a), backgroundColor.a);
 }
\ No newline at end of file

modules/vis/glsl/simpleraycaster.frag

@@ -127,7 +127,7 @@ vec4 performRaycasting(in vec3 entryPoint, in vec3 exitPoint, in vec2 texCoords)
 
             // accomodate for variable sampling rates
             color.a = 1.0 - pow(1.0 - color.a, _samplingStepSize * SAMPLING_BASE_INTERVAL_RCP);
-            result.rgb = mix(color.rgb, result.rgb, result.a);
+            result.rgb = result.rgb + color.rgb * color.a  * (1.0 - result.a);
             result.a = result.a + (1.0 -result.a) * color.a;
         }
 

modules/vis/glsl/volumeexplorer.frag

+// ================================================================================================
+// 
+// This file is part of the CAMPVis Software Framework.
+// 
+// If not explicitly stated otherwise: Copyright (C) 2012-2013, 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".
+// 
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file 
+// except in compliance with the License. You may obtain a copy of the License at
+// 
+// http://www.apache.org/licenses/LICENSE-2.0
+// 
+// Unless required by applicable law or agreed to in writing, software distributed under the 
+// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, 
+// either express or implied. See the License for the specific language governing permissions 
+// and limitations under the License.
+// 
+// ================================================================================================
+
+in vec3 ex_TexCoord;
+out vec4 out_Color;
+
+#include "tools/background.frag"
+#include "tools/texture2d.frag"
+
+uniform sampler2D _colorTexture;
+uniform sampler2D _depthTexture;
+uniform TextureParameters2D _texParams;
+
+uniform bool _renderBackground = false;
+
+void main() {
+    out_Color = texture(_colorTexture, ex_TexCoord.xy);
+    gl_FragDepth = texture(_depthTexture, ex_TexCoord.xy).r;
+
+    if (_renderBackground) {
+        out_Color = blendBackground(ex_TexCoord.xy, out_Color);
+    }
+}

modules/vis/processors/sliceextractor.cpp

@@ -147,6 +147,9 @@ namespace campvis {
                 float ratioRatio = sliceRatio / renderTargetRatio;
                 tgt::mat4 modelMatrix = (ratioRatio > 1) ? tgt::mat4::createScale(tgt::vec3(1.f, 1.f / ratioRatio, 1.f)) : tgt::mat4::createScale(tgt::vec3(ratioRatio, 1.f, 1.f));
 
+                if (p_sliceOrientation.getValue() == XY_PLANE)
+                    modelMatrix.t11 *= -1;
+
                 // prepare OpenGL
                 _shader->activate();
                 decorateRenderProlog(data, _shader);
@@ -186,7 +189,7 @@ namespace campvis {
                         modelMatrix.t11 = 0.f;
                         modelMatrix.t03 = 0.f;
                         modelMatrix.t13 = 2.f * sliceTexCoord.y - 1.f;
-                        modelMatrix.t13 *= (ratioRatio > 1) ? 1.f / ratioRatio : 1.f;
+                        modelMatrix.t13 *= (ratioRatio > 1) ? -1.f / ratioRatio : -1.f;
                         _shader->setUniform("_modelMatrix", modelMatrix);
                         _shader->setUniform("_color", p_ySliceColor.getValue());
                         QuadRdr.renderQuad(GL_LINE_STRIP);

modules/vis/processors/volumeexplorer.cpp

@@ -32,6 +32,7 @@
 #include "core/datastructures/renderdata.h"
 
 #include "core/classification/simpletransferfunction.h"
+#include "core/pipeline/processordecoratorbackground.h"
 #include "core/tools/quadrenderer.h"
 
 namespace campvis {
@@ -57,6 +58,9 @@ namespace campvis {
         addProperty(&p_inputVolume);
         addProperty(&p_outputImage);
 
+        addDecorator(new ProcessorDecoratorBackground());
+        decoratePropertyCollection(this);
+        
         p_seProperties.addPropertyCollection(_sliceExtractor);
         _sliceExtractor.p_lqMode.setVisible(false);
         _sliceExtractor.p_sourceImageID.setVisible(false);
@@ -100,7 +104,7 @@ namespace campvis {
         _raycaster.init();
         _sliceExtractor.init();
 
-        _shader = ShdrMgr.load("core/glsl/passthrough.vert", "modules/vis/glsl/quadview.frag", "");
+        _shader = ShdrMgr.load("core/glsl/passthrough.vert", "modules/vis/glsl/volumeexplorer.frag", "");
         _shader->setAttributeLocation(0, "in_Position");
         _shader->setAttributeLocation(1, "in_TexCoord");
 
@@ -181,14 +185,20 @@ namespace campvis {
         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
         if (vrImage != 0) {
+            decorateRenderProlog(data, _shader);
+            _shader->setUniform("_renderBackground", true);
+
             vrImage->bind(_shader, colorUnit, depthUnit);
             float ratio = static_cast<float>(vrs.x) / static_cast<float>(rts.x);
             _shader->setUniform("_modelMatrix", tgt::mat4::createScale(tgt::vec3(vrs.x, vrs.y, .5f)));
             _shader->setUniform("_viewMatrix", tgt::mat4::createTranslation(tgt::vec3(srs.x, 0.f, 0.f)));
             _quad->render(GL_POLYGON);
+
+            _shader->setUniform("_renderBackground", false);
+            decorateRenderEpilog(_shader);
         }
-        if (xSliceImage != 0) {
-            xSliceImage->bind(_shader, colorUnit, depthUnit);
+        if (zSliceImage != 0) {
+            zSliceImage->bind(_shader, colorUnit, depthUnit);
             _shader->setUniform("_modelMatrix", tgt::mat4::createScale(tgt::vec3(srs.x, srs.y, .5f)));
             _shader->setUniform("_viewMatrix", tgt::mat4::createTranslation(tgt::vec3(0.f, 2.f * srs.y, 0.f)));
             _quad->render(GL_POLYGON);
@@ -199,8 +209,8 @@ namespace campvis {
             _shader->setUniform("_viewMatrix", tgt::mat4::createTranslation(tgt::vec3(0.f, srs.y, 0.f)));
             _quad->render(GL_POLYGON);
         }
-        if (zSliceImage != 0) {
-            zSliceImage->bind(_shader, colorUnit, depthUnit);
+        if (xSliceImage != 0) {
+            xSliceImage->bind(_shader, colorUnit, depthUnit);
             _shader->setUniform("_modelMatrix", tgt::mat4::createScale(tgt::vec3(srs.x, srs.y, .5f)));
             _shader->setUniform("_viewMatrix", tgt::mat4::createTranslation(tgt::vec3(0.f, 0.f, 0.f)));
             _quad->render(GL_POLYGON);

modules/vis/processors/volumeexplorer.h

@@ -31,7 +31,9 @@
 #include "core/eventhandlers/trackballnavigationeventlistener.h"
 #include "core/eventhandlers/transfuncwindowingeventlistener.h"
 
+#include "core/pipeline/abstractprocessordecorator.h"
 #include "core/pipeline/visualizationprocessor.h"
+
 #include "core/properties/datanameproperty.h"
 #include "core/properties/numericproperty.h"
 #include "core/properties/metaproperty.h"
@@ -49,7 +51,7 @@ namespace campvis {
     /**
      * Combines a volume raycaster and 3 slice views for explorative volume visualization.
      */
-    class VolumeExplorer : public VisualizationProcessor, public tgt::EventListener {
+    class VolumeExplorer : public VisualizationProcessor, public HasProcessorDecorators, public tgt::EventListener {
     public:
         /**
          * Constructs a new VolumeExplorer Processor