Update renderable path to fade away with distance

data/scene/osirisrex/osirisrex/osirisrex.mod

@@ -235,32 +235,8 @@ return {
         },
         GuiName = "/Solar/OsirisRexPathSolar"
     },
-    {   
-        Name = "OsirisRexPathLocal",
-        Parent = "Bennu2",
-        Renderable = {
-            Type = "RenderablePath",
-            Body = "OSIRIS-REX",
-            Frame = "GALACTIC",
-            Observer = BENNU_BODY,
-            RGB = { 0.8, 0.0, 0.5},
-            TimeSteps = 900,
-            PointSteps = 4, -- Every fourth point is marked differently to show hours 
-            Textures = {
-                Type = "simple",
-                Color = "textures/glare_blue.png",
-                -- need to add different texture
-            },  
-            DrawLine = true,
-            
-            StartTime = "2016 SEP 8 12:00:00",
-            EndTime = "2023 SEP 24 12:00:00"
-        },
-        GuiName = "/Solar/OsirisRexPathLocal"
-    },
-]]
-
-    -- Asteroid Dance trail
+    ]]
+    -- Trail relative to Bennu
     {   
         Name = "OsirisRexTrailLocal",
         Parent = "Bennu2",

modules/base/rendering/renderablepath.cpp

@@ -59,7 +59,6 @@ namespace openspace {
 
 RenderablePath::RenderablePath(const ghoul::Dictionary& dictionary)
     : Renderable(dictionary)
-    , _lineFade("lineFade", "Line Fade", 0.75f, 0.f, 1.f)
     , _lineWidth("lineWidth", "Line Width", 2.f, 1.f, 20.f)
     , _drawLine("drawline", "Draw Line", false)
     , _programObject(nullptr)
@@ -90,7 +89,6 @@ RenderablePath::RenderablePath(const ghoul::Dictionary& dictionary)
         dictionary.getValue(keyDrawLine, drawLine);
     _drawLine = drawLine;
     addProperty(_drawLine);
-    addProperty(_lineFade);
     addProperty(_lineWidth);
     _distanceFade = 1.0;
 }
@@ -164,8 +162,6 @@ void RenderablePath::render(const RenderData& data) {
     _programObject->setUniform("projectionTransform", data.camera.projectionMatrix());
     _programObject->setUniform("pointSteps", _pointSteps);
     _programObject->setUniform("color", _lineColor);
-    _programObject->setUniform("lineFade", _lineFade);
-    _programObject->setUniform("numVertices", nPointsToDraw);
 
     if (_drawLine) {
         glLineWidth(_lineWidth);

modules/base/rendering/renderablepath.h

@@ -64,7 +64,6 @@ private:
 
     glm::vec3 _lineColor;
     glm::vec4 _lastPosition;
-    properties::FloatProperty _lineFade;
     properties::FloatProperty _lineWidth;
     properties::BoolProperty _drawLine;
 

modules/base/shaders/path_fs.glsl

@@ -30,6 +30,8 @@ in vec4 vs_pointColor;
 
 Fragment getFragment() {
 
+	if (vs_pointColor.a < 0.01)
+		discard;
     Fragment frag;
     frag.color = vs_pointColor;
     frag.depth = vs_positionScreenSpace.w;

modules/base/shaders/path_vs.glsl

@@ -30,8 +30,6 @@ uniform vec3 color;
 uniform mat4 modelViewTransform;
 uniform mat4 projectionTransform;
 uniform int pointSteps;
-uniform float lineFade;
-uniform int numVertices;
 
 out vec4 vs_positionScreenSpace;
 out vec4 vs_pointColor;
@@ -39,24 +37,26 @@ out vec4 vs_pointColor;
 #include "PowerScaling/powerScaling_vs.hglsl"
 
 void main() {    
-    vec4 positionClipSpace = projectionTransform * modelViewTransform * in_point_position;
+    vec4 positionCameraSpace = modelViewTransform * in_point_position;
+    vec4 positionClipSpace = projectionTransform * positionCameraSpace;
     vs_positionScreenSpace = z_normalization(positionClipSpace);
     
     gl_Position = vs_positionScreenSpace;
             
     if(mod(gl_VertexID, pointSteps) == 0) {
         vs_pointColor.rgb = color;
-        gl_PointSize = 10.0f;  
+        gl_PointSize = 5.0f;  
     }
     else {
         vs_pointColor.rgb = (color + vec3(0.6f, 0.6f, 0.6f)) / 2;
-        gl_PointSize = 5.f;  
-    }
-    if (lineFade == 0)
-        vs_pointColor.a = 1.0;
-    else
-    {
-        int threshHold = int(lineFade * numVertices);
-        vs_pointColor.a = float(gl_VertexID - threshHold) / (numVertices - threshHold);
+        gl_PointSize = 2.f;  
     }
+
+    // I don't like this random variable k defined in powerScalingMath.hglsl.
+    // Will ignore it and use 10 in protest of psc dependencies. /KB
+    // float maximumDistance = pow(k, 10);
+    float maximumDistance = pow(10, 10);
+    float distanceToCamera = length(positionCameraSpace.xyz);
+    
+    vs_pointColor.a = maximumDistance / (distanceToCamera/100);
 }