Volume raycasting jittering

- Added jitter to volume rendering, reducing artefacts
- Added tracking of more shader files to update the resolve shader

include/openspace/abuffer/abuffer.h

@@ -79,6 +79,9 @@ private:
 	std::vector<ghoul::filesystem::File*> _samplerFiles;
 	std::vector<std::string> _samplers;
 
+	// Development functionality to update shader for changes in several files
+	std::vector<ghoul::filesystem::File*> _shaderFiles;
+
 
 
 };		// ABuffer

shaders/ABuffer/abufferSort.hglsl

@@ -56,6 +56,10 @@ float pscLength(vec4 v1, vec4 v2) {
 	return length(vector.xyz)*pow(k,vector.w);
 }
 
+float permute(float i) {
+    return mod((62.0*i*i + i), 961.0); // permutation polynomial; 62=2*31; 961=31*31
+}
+
 void sort_fragments_list(uint frag_count) {
 	uint i,j;
 	ABufferStruct_t tmp;
@@ -91,6 +95,17 @@ void sort_fragments_list(uint frag_count) {
 					// volume_zlength[ii] = pscLength(_pos_(fragments[jj]), startPosition);
 					volumeStepSize[ii] = 1.0/(length(volume_direction[ii]*volume_dim[ii]));
 					// volume_length[ii] = pscLength(_pos_(fragments[jj]), startPosition);
+
+					if(volumeStepSize[ii] < volume_length[ii]) {
+						// jittering
+						float x = gl_FragCoord.x;
+	            		float y = gl_FragCoord.y;
+	            		float jitterValue = float(permute(x + permute(y))) / 961.0;
+	            		jitterValue *= 0.004;
+	            		vec3 frontPosNew = startColor + (jitterValue*volume_length[ii])*volume_direction[ii];
+	            		volume_position[ii] = frontPosNew;
+					}
+					
 					break;
 				}
 			}

shaders/pscstandard_fs.glsl

@@ -29,7 +29,8 @@ uniform sampler2D texture1;
 
 in vec2 vs_st;
 in vec4 vs_normal;
-in vec4 vs_position;
+in vec3 vs_position;
+in float s;
 
 #include "ABuffer/abufferStruct.hglsl"
 #include "ABuffer/abufferAddToBuffer.hglsl"
@@ -37,10 +38,11 @@ in vec4 vs_position;
 
 void main()
 {
-	float depth = pscDepth(vs_position);
+	vec4 position = vec4(vs_position,s);
+	float depth = pscDepth(position);
 	vec4 diffuse = texture(texture1, vs_st);
 
-	ABufferStruct_t frag = createGeometryFragment(diffuse, vs_position, depth);
+	ABufferStruct_t frag = createGeometryFragment(diffuse, position, depth);
 	addToBuffer(frag);
 
 	discard;

shaders/pscstandard_vs.glsl

@@ -31,13 +31,6 @@ uniform mat4 camrot;
 uniform vec2 scaling;
 uniform vec4 objpos;
 uniform float time;
-uniform sampler2D texture1;
-uniform sampler2D texture2;
-uniform sampler2D texture3;
-uniform float TessLevel;
-uniform bool Wireframe;
-uniform bool Lightsource;
-uniform bool UseTexture;
 
 layout(location = 0) in vec4 in_position;
 //in vec3 in_position;
@@ -47,10 +40,10 @@ layout(location = 2) in vec3 in_normal;
 out vec2 vs_st;
 out vec3 vs_stp;
 out vec4 vs_normal;
-out vec4 vs_position;
+out vec3 vs_position;
+out float s;
 
 const float k = 10.0;
-const float dgr_to_rad = 0.0174532925;
 
 vec4 psc_addition(vec4 v1, vec4 v2) {
 	float ds = v2.w - v1.w;
@@ -92,25 +85,27 @@ void main()
 	//vec4 lvp = ModelTransform * in_position;
 	
 	// PSC addition; local vertex position and the object power scaled world position
-	vs_position = psc_addition(vec4(local_vertex_pos,in_position.w),objpos);
-	//vs_position = psc_addition(lvp,objpos);
+	vec4 position = psc_addition(vec4(local_vertex_pos,in_position.w),objpos);
+	//position = psc_addition(lvp,objpos);
 	
 	// PSC addition; rotated and viewscaled vertex and the cmaeras negative position
-	vs_position = psc_addition(vs_position,vec4(-campos.xyz,campos.w));
+	position = psc_addition(position,vec4(-campos.xyz,campos.w));
 	
 	// rotate the camera
-	local_vertex_pos =  mat3(camrot) * vs_position.xyz;
-	vs_position = vec4(local_vertex_pos, vs_position.w);
-	//vs_position =  camrot* vs_position;
+	local_vertex_pos =  mat3(camrot) * position.xyz;
+	position = vec4(local_vertex_pos, position.w);
+	//position =  camrot* position;
 
 	// rescales the scene to fit inside the view frustum
 	// is set from the main program, but these are decent values
 	// scaling = vec2(1.0, -8.0);
 
 	// project using the rescaled coordinates,
-	//vec4 vs_position_rescaled = psc_scaling(vs_position, scaling);
-	vec4 vs_position_rescaled = psc_to_meter(vs_position, scaling);
-	vs_position = vs_position_rescaled;
+	//vec4 vs_position_rescaled = psc_scaling(position, scaling);
+	vec4 vs_position_rescaled = psc_to_meter(position, scaling);
+	position = vs_position_rescaled;
+	vs_position = vs_position_rescaled.xyz;
+	s = vs_position_rescaled.w;
 
 
 	// project the position to view space

src/abuffer/abuffer.cpp

@@ -62,6 +62,14 @@ ABuffer::~ABuffer() {
 
 	if(_resolveShader)
 		delete _resolveShader;
+
+	for(auto file: _samplerFiles) {
+		delete file;
+	}
+	for(auto file: _shaderFiles) {
+		delete file;
+	}
+
 }
 
 bool ABuffer::initializeABuffer() {
@@ -73,6 +81,17 @@ bool ABuffer::initializeABuffer() {
     };
     _fragmentShaderFile->setCallback(shaderCallback);
 
+    // Development functionality to update shader for changes in several files
+    auto addFunc = [this, shaderCallback](const std::string& path) {
+    	ghoul::filesystem::File* f = new ghoul::filesystem::File(path, false);
+    	f->setCallback(shaderCallback);
+    	_shaderFiles.push_back(f);
+    };
+    addFunc("${SHADERS}/ABuffer/abufferSort.hglsl");
+    addFunc("${SHADERS}/ABuffer/abufferAddToBuffer.hglsl");
+    addFunc("${SHADERS}/ABuffer/abufferStruct.hglsl");
+    
+
     _resolveShader = nullptr;
     generateShaderSource();
     updateShader();

src/abuffer/abufferSingleLinked.cpp

@@ -33,7 +33,6 @@
 #include <string>
 
 #define MAX_LAYERS 10
-#define BUFFER_OFFSET(i) ((char *)NULL + (i))
 
 namespace {
 	std::string _loggerCat = "ABufferSingleLinked";