Issue #216: Allow changing colors for comet tails

src/celengine/body.cpp

@@ -1110,6 +1110,15 @@ void Body::setOrbitColor(const Color& c)
 }
 
 
+/*! Set the comet tail color
+ *
+ */
+void Body::setCometTailColor(const Color& c)
+{
+    cometTailColor = c;
+}
+
+
 /*! Set whether or not the object should be considered when calculating
  *  secondary illumination (e.g. planetshine.)
  */

src/celengine/body.h

@@ -327,6 +327,9 @@ class Body : public CatEntry
     Color getOrbitColor() const { return orbitColor; }
     void setOrbitColor(const Color&);
 
+    Color getCometTailColor() const { return cometTailColor; }
+    void setCometTailColor(const Color& c);
+
     int getOrbitClassification() const;
 
     enum
@@ -402,6 +405,7 @@ class Body : public CatEntry
     std::list<ReferenceMark*>* referenceMarks{ nullptr };
 
     Color orbitColor;
+    Color cometTailColor{ 0.5f, 0.5f, 0.75f };
 
     bool visible{ true };
     bool clickable{ true };

src/celengine/render.cpp

@@ -5562,7 +5562,8 @@ struct CometTailVertex
 
 static CometTailVertex cometTailVertices[CometTailSlices * MaxCometTailPoints];
 
-static void ProcessCometTailVertex(const CometTailVertex& v,
+static void ProcessCometTailVertex(const Color& cometTailColor,
+                                   const CometTailVertex& v,
                                    const Vector3f& viewDir,
                                    float fadeDistFromSun)
 {
@@ -5571,7 +5572,8 @@ static void ProcessCometTailVertex(const CometTailVertex& v,
 
     float fadeFactor = 0.5f - 0.5f * (float) tanh(fadeDistFromSun - 1.0f / fadeDistFromSun);
     float shade = abs(viewDir.dot(v.normal) * v.brightness * fadeFactor);
-    glColor4f(0.5f, 0.5f, 0.75f, shade);
+    glColor4f(cometTailColor.red(), cometTailColor.green(),
+              cometTailColor.blue(), shade);
     glVertex(v.point);
 }
 
@@ -5737,12 +5739,17 @@ void Renderer::renderCometTail(const Body& body,
         int n = i * nTailSlices;
         for (int j = 0; j < nTailSlices; j++)
         {
-            ProcessCometTailVertex(cometTailVertices[n + j], viewDir, fadeDistance);
-            ProcessCometTailVertex(cometTailVertices[n + j + nTailSlices],
+            ProcessCometTailVertex(body.getCometTailColor(),
+                                   cometTailVertices[n + j], viewDir,
+                                   fadeDistance);
+            ProcessCometTailVertex(body.getCometTailColor(),
+                                   cometTailVertices[n + j + nTailSlices],
                                    viewDir, fadeDistance);
         }
-        ProcessCometTailVertex(cometTailVertices[n], viewDir, fadeDistance);
-        ProcessCometTailVertex(cometTailVertices[n + nTailSlices],
+        ProcessCometTailVertex(body.getCometTailColor(),
+                               cometTailVertices[n], viewDir, fadeDistance);
+        ProcessCometTailVertex(body.getCometTailColor(),
+                               cometTailVertices[n + nTailSlices],
                                viewDir, fadeDistance);
         glEnd();
     }

src/celengine/solarsys.cpp

@@ -999,6 +999,13 @@ static Body* CreateBody(const string& name,
         }
     }
 
+    // Read comet tail color
+    Color cometTailColor;
+    if(planetData->getColor("TailColor", cometTailColor))
+    {
+        body->setCometTailColor(cometTailColor);
+    }
+
     bool clickable = true;
     if (planetData->getBoolean("Clickable", clickable))
     {