IpsviRaycaster cleanup and added some documentation.

core/glsl/tools/shading.frag

@@ -115,7 +115,7 @@ vec3 calculatePhongShading(in vec3 position, in LightSource light, in vec3 camer
  * \param   normal          Normal
  * \param   materialColor   Material color (used for all shading coefficients)
  */
-vec3 calculatePhongShading(in vec3 position, in LightSource light, in vec3 camera, in vec3 normal, in vec3 materialColor) {
+vec3 calculatePhongShading(in vec3 position, in vec3 ambientColorOverride, LightSource light, in vec3 camera, in vec3 normal, in vec3 materialColor) {
     vec3 N = normalize(normal);
     vec3 V = normalize(camera - position);
 
@@ -124,7 +124,7 @@ vec3 calculatePhongShading(in vec3 position, in LightSource light, in vec3 camer
     float d = length(L);
     L /= d;
 
-    vec3 toReturn = materialColor * light._ambientColor;   // ambient term
+    vec3 toReturn = materialColor * ambientColorOverride;   // ambient term
     toReturn += materialColor * getDiffuseTerm(light._diffuseColor, N, L);
     toReturn += materialColor * getSpecularTerm(light._specularColor, N, L, V, light._shininess);
     #ifdef PHONG_APPLY_ATTENUATION
@@ -133,6 +133,19 @@ vec3 calculatePhongShading(in vec3 position, in LightSource light, in vec3 camer
     return toReturn;
 }
 
+/**
+ * Computes the phong shading according to the given parameters.
+ * 
+ * \param   position        sample position
+ * \param   light           LightSource
+ * \param   camera          Camera position
+ * \param   normal          Normal
+ * \param   materialColor   Material color (used for all shading coefficients)
+ */
+vec3 calculatePhongShading(in vec3 position, in LightSource light, in vec3 camera, in vec3 normal, in vec3 materialColor) {
+    return calculatePhongShading(position, light._ambientColor, light, camera, normal, materialColor);
+}
+
 
 /**
  * Computes the phong shading intensity according to the given parameters.

modules/vis/glsl/ipsviraycaster.frag

@@ -90,6 +90,9 @@ ivec2 calcIcSamplePosition(vec3 worldPosition) {
     return ivec2(round(dot(worldProjected, _icRightVector)), round(dot(worldProjected, _icUpVector)));
 }
 
+// the composite function can be used for additional shadow ray integration
+// from the current sample to the position of the IC.
+// However, it's currently not used for performance reasons
 void composite(vec3 startPosition, vec3 endPosition, inout float opacity) {
     vec3 direction = endPosition - startPosition;
     float t = _samplingStepSize;
@@ -145,11 +148,6 @@ vec4 performRaycasting(in vec3 entryPoint, in vec3 exitPoint, in vec2 texCoords)
         // optimization: Only store/load when the icPosition has changed
         // otherwise we can reuse the variables from the previous sample
         if (icPositionPrev != icPosition) {
-            // if there is no updated illumination information to be saved, 
-            // carry over the old pixel
-            //if (! toBeSaved)
-            //    icOut = imageLoad(_icImageIn, icPositionPrev);
-
             // write illumination information
             if (toBeSaved)
                 imageStore(_icImageOut, icPositionPrev, vec4(icOut));
@@ -171,8 +169,7 @@ vec4 performRaycasting(in vec3 entryPoint, in vec3 exitPoint, in vec2 texCoords)
         // perform compositing
         if (color.a > 0.0) {
             // compute gradient (needed for shading and normals)
-            vec3 gradient = computeGradient(_volume, _volumeTextureParams, samplePosition);
-            color.rgb = calculatePhongShading(worldPos, _lightSource, _cameraPosition, gradient, color.rgb);
+            vec3 gradient = computeGradient(_volume, _volumeTextureParams, samplePosition);            
 
             // accomodate for variable sampling rates
             color.a = 1.0 - pow(1.0 - color.a, _samplingStepSize * SAMPLING_BASE_INTERVAL_RCP);
@@ -186,7 +183,8 @@ vec4 performRaycasting(in vec3 entryPoint, in vec3 exitPoint, in vec2 texCoords)
             toBeSaved = true;
 
             // apply shadowing
-            color.rgb *= (1.0 - icIn * _shadowIntensity); 
+            const vec3 ambientColorOverride = _lightSource._ambientColor * (1.0 - icIn * _shadowIntensity);
+            color.rgb = calculatePhongShading(worldPos, ambientColorOverride, _lightSource, _cameraPosition, gradient, color.rgb);
 
             // front-to-back compositing along view direction
             result.rgb = result.rgb + color.rgb * color.a  * (1.0 - result.a);
@@ -212,8 +210,6 @@ vec4 performRaycasting(in vec3 entryPoint, in vec3 exitPoint, in vec2 texCoords)
         t += _samplingStepSize / len;
     }
 
-    //if (! toBeSaved)
-    //    icOut = imageLoad(_icImageIn, icPositionPrev);
     if (toBeSaved)
         imageStore(_icImageOut, icPositionPrev, vec4(icOut));
 

modules/vis/processors/ipsviraycaster.h

@@ -45,7 +45,11 @@ namespace campvis {
     class VoxelHierarchyMapper;
 
     /**
-     * Performs a simple volume ray casting.
+     * Raycaster that implements the Image Plane Sweep Volume Illumation algorithm of Sundn et al.
+     * This raycasting processor supports real-time directional light shadowing and additionally
+     * uses the VoxelHierarchyMapper for optimized entry-exit points.
+     * 
+     * Requires OpenGL 4.4!
      */
     class CAMPVIS_MODULES_API IpsviRaycaster : public RaycastingProcessor {
     public:
@@ -71,7 +75,7 @@ namespace campvis {
         /// \see AbstractProcessor::getName()
         virtual const std::string getName() const { return getId(); };
         /// \see AbstractProcessor::getDescription()
-        virtual const std::string getDescription() const { return "Performs a simple volume ray casting."; };
+        virtual const std::string getDescription() const { return "Raycaster that implements the Image Plane Sweep Volume Illumation algorithm of Sundn et al."; };
         /// \see AbstractProcessor::getAuthor()
         virtual const std::string getAuthor() const { return "Christian Schulte zu Berge <christian.szb@in.tum.de>"; };
         /// \see AbstractProcessor::getProcessorState()
@@ -83,22 +87,19 @@ namespace campvis {
         virtual void deinit();
 
         DataNameProperty p_lightId;                 ///< Name/ID for the LightSource to use
-        IntProperty p_sweepLineWidth;
-        IVec2Property p_icTextureSize;
-        FloatProperty p_shadowIntensity;
-
-        IntProperty p_numLines;
+        IntProperty p_sweepLineWidth;               ///< Width of the sweep line in pixels
+        IVec2Property p_icTextureSize;              ///< Size of the Illumination Cache texture
+        FloatProperty p_shadowIntensity;            ///< Intensity of the shadowing effect
     
     protected:
         /// \see RaycastingProcessor::processImpl()
         virtual void processImpl(DataContainer& data, ImageRepresentationGL::ScopedRepresentation& image);
 
         void processDirectional(DataContainer& data, ImageRepresentationGL::ScopedRepresentation& image, const CameraData& camera, const LightSourceData& light);
-
         void processPointLight(DataContainer& data, ImageRepresentationGL::ScopedRepresentation& image, const CameraData& camera, const LightSourceData& light);
 
-        VoxelHierarchyMapper* _vhm;
-        cgt::Texture* _icTextures[2];
+        VoxelHierarchyMapper* _vhm;     ///< for optimizing entry/exit points
+        cgt::Texture* _icTextures[2];   ///< Illumination cache textures
 
         static const std::string loggerCat_;
     };