Fixed Cylinder, Cone, Geosphere subdivision

The automatic calculation of subdivisions of the Cone, Cylinder, Geosphere Mesh helper functions produced different subdivision counts, dependent on voxel size. This reduced the quality massively at smaller voxel sizes. (These functions were not used outside tests, as the Shape Kernel has more advanced functionality).

PicoGK_Utils.cs

@@ -326,12 +326,17 @@ static public Mesh mshCreateCylinder( Vector3? vecScale     = null,
 
             if (iSides <= 0)
             {
+                float fVoxA = fA / Library.fVoxelSizeMM;
+                float fVoxB = fB / Library.fVoxelSizeMM;
                 //Ramanujan's ellipse perimeter
                 //P ≈ π [ 3 (a + b) - √[(3a + b) (a + 3b) ]]
                 //P ≈ π(a + b) [ 1 + (3h) / (10 + √(4 - 3h) ) ], where h = (a - b)2/(a + b)2
 
-                float fP    = MathF.PI * (3.0f * (fA + fB) - MathF.Sqrt((3.0f * fA + fB) * (fA + 3.0f * fB)));
-                iSides      = 2 * (int)MathF.Ceiling(fP);
+                float fP    = float.Pi * (3.0f * (fVoxA + fVoxB)
+                                - float.Sqrt((3.0f * fVoxA + fVoxB)
+                                * (fVoxA + 3.0f * fVoxB)));
+
+                iSides      = 2 * (int) float.Ceiling(fP);
             }
 
             if (iSides < 3)
@@ -388,7 +393,13 @@ static public Mesh mshCreateCone(Vector3? vecScale = null,
 
             if (iSides <= 0)
             {
-                float fP = MathF.PI * (3.0f * (fA + fB) - MathF.Sqrt((3.0f * fA + fB) * (fA + 3.0f * fB)));
+                float fVoxA = fA / Library.fVoxelSizeMM;
+                float fVoxB = fB / Library.fVoxelSizeMM;
+
+                float fP =  float.Pi * (3.0f * (fVoxA + fVoxB)
+                            - float.Sqrt((3.0f * fVoxA + fVoxB)
+                            * (fVoxA + 3.0f * fVoxB)));
+
                 iSides = 2 * (int)MathF.Ceiling(fP);
             }
 
@@ -499,7 +510,10 @@ static public Mesh mshCreateGeoSphere(Vector3? vecScale = null,
 
             if (iSubdivisions <= 0)
             {
-                int iTargetTriangles = (int)MathF.Ceiling(fApproxEllipsoidSurfaceArea(vecRadii));
+                int iTargetTriangles = (int) MathF.Ceiling(
+                                    fApproxEllipsoidSurfaceArea(vecRadii)
+                                    / Library.fVoxelSizeMM
+                                    / Library.fVoxelSizeMM);
 
                 iSubdivisions = 1;
                 int iTriangles = 80;