/**
* @param pDieMesh a mesh of a Die to process
* @return a list of DieAreas based on all the triangles of the FIRST submesh.
*/
private static List <DieArea> convertMeshTrianglesToDieAreaInstances(Mesh pDieMesh)
{
List <DieArea> result = new List <DieArea>();
//get all mesh data
int[] triangleIndices = pDieMesh.GetTriangles(0);
int triangleIndicesLength = triangleIndices.Length;
Vector3[] vertices = pDieMesh.vertices;
Vector3[] normals = pDieMesh.normals;
//convert all mesh data into a list of areas
for (int i = 0; i < triangleIndicesLength; i += 3)
{
DieArea area = new DieArea();
int index1 = triangleIndices[i];
int index2 = triangleIndices[i + 1];
int index3 = triangleIndices[i + 2];
Vector3 vertex1 = vertices[index1];
Vector3 vertex2 = vertices[index2];
Vector3 vertex3 = vertices[index3];
//first calculate normal using cross product, this is not necessarily of length one....
area.normal = Vector3.Cross(vertex2 - vertex1, vertex3 - vertex1);
//now use that normal to calculate area of the triangle spanned by v1,v2,v3:
//the magnitude (or length) of the vector a×b, written as ∥a×b∥,
//is the area of the parallelogram spanned by a and b, half of it gives us the triangle
//a = v2-v1 here and b = v3-v1 (see Wikipedia)
area.area = area.normal.magnitude / 2;
//now normalize the normal since we like'm at length 1, size matters! ;).
area.normal.Normalize();
//average the centerpoint
area.centerPoint = (vertex1 + vertex2 + vertex3) / 3.0f;
//lastly add the result to our area list
result.Add(area);
}
return(result);
}
/**
* @param pAreasToCombine a list of all areas to search through for areas with similar normals
* @param pMaxAreaSize (out parameter) the size of the biggest area found
* @return a list of combined areas that all have unique normals
*/
private static List <DieArea> combineDieAreasWithSimilarNormals(List <DieArea> pAreasToCombine, out float pMaxAreaSize)
{
//process all areas so that we are left with
//combined areas that all have a unique normal
List <DieArea> uniqueAreas = new List <DieArea>();
float maxAreaSize = 0;
for (int i = 0; i < pAreasToCombine.Count; i++)
{
DieArea currentArea = pAreasToCombine[i];
DieArea similarArea = findAreaWithSimilarNormal(uniqueAreas, currentArea.normal);
if (similarArea == null)
{
//if there was no area that had a similar normal, create one:
similarArea = new DieArea();
similarArea.area = currentArea.area;
similarArea.centerPoint = currentArea.centerPoint;
similarArea.normal = currentArea.normal;
similarArea.areaCount = 1;
uniqueAreas.Add(similarArea);
}
else
{
//if there already was an area in the uniqueArea list with a similar normal
//combine it with the data for the current area
similarArea.area += currentArea.area;
//calculcate the new centerpoint using the weighted average of the previous centerpoint with the new one
similarArea.centerPoint = (similarArea.centerPoint * similarArea.areaCount + currentArea.centerPoint) / (similarArea.areaCount + 1);
similarArea.areaCount++;
}
//to be able to do the cutoff calculation in a later step we need to
//keep track of the maximum area size thus far
maxAreaSize = Mathf.Max(maxAreaSize, similarArea.area);
}
pMaxAreaSize = maxAreaSize;
return(uniqueAreas);
}
