fix: Improve clouds by flattening dome (temporary test)

Author: twpol

Source/RunActivity/Viewer3D/Sky.cs

@@ -132,6 +132,7 @@ public class SkyPrimitive : RenderPrimitive
         public const float SkyRadius = 6020;
         public const float MoonRadius = 6010;
         public const float CloudsRadius = 6000;
+        public const float CloudsFlatness = 0.1f;
 
         public SkyElement Element;
 
@@ -175,7 +176,7 @@ public SkyPrimitive(RenderProcess renderProcess)
             var vertexIndex = 0;
             var indexIndex = 0;
             InitializeDomeVertexList(ref vertexIndex, SkyRadius);
-            InitializeDomeVertexList(ref vertexIndex, CloudsRadius);
+            InitializeDomeVertexList(ref vertexIndex, CloudsRadius, CloudsFlatness);
             InitializeDomeIndexList(ref indexIndex);
             InitializeMoonLists(ref vertexIndex, ref indexIndex);
             Debug.Assert(vertexIndex == VertexCount, $"Did not initialize all verticies; expected {VertexCount}, got {vertexIndex}");
@@ -223,10 +224,10 @@ public override void Draw(GraphicsDevice graphicsDevice)
             }
         }
 
-        void InitializeDomeVertexList(ref int index, float radius)
+        void InitializeDomeVertexList(ref int index, float radius, float flatness = 1)
         {
             // Single vertex at zenith
-            VertexList[index].Position = new Vector3(0, radius, 0);
+            VertexList[index].Position = new Vector3(0, radius * flatness, 0);
             VertexList[index].Normal = Vector3.Normalize(VertexList[index].Position);
             VertexList[index].TextureCoordinate = new Vector2(0.5f, 0.5f);
             index++;
@@ -236,7 +237,7 @@ void InitializeDomeVertexList(ref int index, float radius)
                 var stepCos = (float)Math.Cos(MathHelper.ToRadians(90f * step / DomeStepsMain));
                 var stepSin = (float)Math.Sin(MathHelper.ToRadians(90f * step / DomeStepsMain));
 
-                var y = radius * stepCos;
+                var y = radius * stepCos * flatness;
                 var d = radius * stepSin;
 
                 for (var side = 0; side < DomeSides; side++)