Added properties to change the appearance of stars

include/openspace/rendering/stars/renderablestars.h

@@ -28,6 +28,7 @@
 #include <openspace/rendering/renderable.h>
 #include <openspace/properties/stringproperty.h>
 #include <openspace/properties/optionproperty.h>
+#include <openspace/properties/vectorproperty.h>
 
 #include <ghoul/opengl/programobject.h>
 #include <ghoul/opengl/texture.h>
@@ -69,12 +70,13 @@ private:
 	ghoul::opengl::Texture* _colorTexture;
 	bool _colorTextureIsDirty;
 
-
 	properties::OptionProperty _colorOption;
 	bool _dataIsDirty;
 
-	properties::FloatProperty _spriteBaseSize;
-	properties::FloatProperty _spriteResponseSize;
+    properties::Vec2Property _magnitudeClamp;
+    properties::FloatProperty _exponentialOffset;
+    properties::FloatProperty _exponentialDampening;
+    properties::FloatProperty _scaleFactor;
 
 	ghoul::opengl::ProgramObject* _program;
 	bool _programIsDirty;

shaders/modules/stars/star_ge.glsl

@@ -51,8 +51,11 @@ layout(location = 4) out vec2 texCoord;
 
 uniform mat4 projection;
 
-uniform float spriteBaseSize;
-uniform float spriteResponseSize;
+uniform vec2 magnitudeClamp;
+uniform float exponentialOffset;
+uniform float exponentialDampening;
+uniform float scaleFactor;
+
 
 // As soon as the scalegraph is in place, replace this by a dynamic calculation
 // of apparent magnitude in relation to the camera position ---abock
@@ -67,8 +70,10 @@ void main() {
 
     float M  = vs_brightness[0].z;
 
-    M = clamp(M, 1.0, 4.0);
-    float modifiedSpriteSize = exp((-5 - M) * 0.871);
+    // M = clamp(M, 1.0, 4.0);
+    M = clamp(M, magnitudeClamp[0], magnitudeClamp[1]);
+    // float modifiedSpriteSize = exp((-5 - M) * 0.871);
+    float modifiedSpriteSize = exp((-exponentialOffset - M) * exponentialDampening) * scaleFactor;
 
     for(int i = 0; i < 4; i++){
         vec4 p1     = gl_in[0].gl_Position;

src/rendering/stars/renderablestars.cpp

@@ -84,8 +84,16 @@ RenderableStars::RenderableStars(const ghoul::Dictionary& dictionary)
 	, _colorTextureIsDirty(true)
 	, _colorOption("colorOption", "Color Option")
 	, _dataIsDirty(true)
-	, _spriteBaseSize("spriteBaseSize", "Sprite Base Size", 0.1f, 0.f, 10.f)
-	, _spriteResponseSize("spriteResponseSize", "Sprite Response Size", 1.f, 0.f, 10.f)
+    , _magnitudeClamp(
+        "magnitudeClamp",
+        "Magnitude Clamping",
+        glm::vec2(1.f, 4.f),
+        glm::vec2(-15.f),
+        glm::vec2(15.f)
+      )
+    , _exponentialOffset("exponentialOffset", "Exponential Offset", 5.f, 0.f, 10.f)
+    , _exponentialDampening("exponentialDampening", "Exponential Dampening", 0.871f, 0.f, 1.f)
+    , _scaleFactor("scaleFactor", "Scale Factor", 1.f, 0.f, 10.f)
 	, _program(nullptr)
 	, _programIsDirty(false)
 	, _speckFile("")
@@ -114,14 +122,16 @@ RenderableStars::RenderableStars(const ghoul::Dictionary& dictionary)
 	addProperty(_colorOption);
 	_colorOption.onChange([&]{ _dataIsDirty = true;});
 
-	addProperty(_spriteBaseSize);
-	addProperty(_spriteResponseSize);
-
 	addProperty(_pointSpreadFunctionTexturePath);
 	_pointSpreadFunctionTexturePath.onChange([&]{ _pointSpreadFunctionTextureIsDirty = true;});
 
 	addProperty(_colorTexturePath);
 	_colorTexturePath.onChange([&]{ _colorTextureIsDirty = true; });
+
+    addProperty(_magnitudeClamp);
+    addProperty(_exponentialOffset);
+    addProperty(_exponentialDampening);
+    addProperty(_scaleFactor);
 }
 
 RenderableStars::~RenderableStars() {
@@ -181,13 +191,14 @@ void RenderableStars::render(const RenderData& data) {
 	_program->setUniform("projection", projectionMatrix);
 
 	_program->setUniform("colorOption", _colorOption);
+    _program->setUniform("magnitudeClamp", _magnitudeClamp);
+    _program->setUniform("exponentialOffset", _exponentialOffset);
+    _program->setUniform("exponentialDampening", _exponentialDampening);
+    _program->setUniform("scaleFactor", _scaleFactor);
 	
 	setPscUniforms(_program, &data.camera, data.position);
 	_program->setUniform("scaling", scaling);
 
-	_program->setUniform("spriteBaseSize", _spriteBaseSize);
-	_program->setUniform("spriteResponseSize", _spriteResponseSize);
-
 	ghoul::opengl::TextureUnit psfUnit;
 	psfUnit.activate();
 	if (_pointSpreadFunctionTexture)