public static void CalculateTargetPositionForPairContraction(ref MeshPairContraction pair, Vector3[] verts, Quadric[] vertQuadrics)
{
Vector3 v0 = verts[pair.v0], v1 = verts[pair.v1];
Quadric Q0 = vertQuadrics[pair.v0], Q1 = vertQuadrics[pair.v1];
Quadric Q = Q0 + Q1;
if (Q.Optimize(ref pair.contractedPosition, 1e-12))
{
pair.error = Q.Evaluate(pair.contractedPosition);
}
else
{
double ei = Q.Evaluate(v0), ej = Q.Evaluate(v1);
if (ei < ej)
{
pair.error = ei;
pair.contractedPosition = v0;
}
else
{
pair.error = ej;
pair.contractedPosition = v1;
}
}
}
public static MinHeap <MeshPairContraction> GeneratePairContractions(MeshIndexTriangle[] indexTris, Vector3[] verts, Quadric[] vertQuadrics)
{
List <MeshPairContraction> pairContractions = new List <MeshPairContraction>();
foreach (MeshIndexTriangle tri in indexTris)
{
MeshPairContraction e0 = new MeshPairContraction(tri.v0, tri.v1),
e1 = new MeshPairContraction(tri.v1, tri.v2),
e2 = new MeshPairContraction(tri.v2, tri.v0);
if (!pairContractions.Contains(e0))
{
pairContractions.Add(e0);
}
if (!pairContractions.Contains(e1))
{
pairContractions.Add(e1);
}
if (!pairContractions.Contains(e2))
{
pairContractions.Add(e2);
}
}
//Calculate point that each pair contraction will contract to if it is to be done
CalculateTargetPositionForAllPairContractions(ref pairContractions, verts, vertQuadrics);
MinHeap <MeshPairContraction> heap = new MinHeap <MeshPairContraction>(pairContractions);
return(heap);
}
public static void CalculateTargetPositionForAllPairContractions(ref List <MeshPairContraction> pairContractions, Vector3[] verts, Quadric[] vertQuadrics)
{
for (int i = 0; i < pairContractions.Count; i++)
{
MeshPairContraction pair = pairContractions[i];
CalculateTargetPositionForPairContraction(ref pair, verts, vertQuadrics);
pairContractions[i] = pair;
}
}
public static void ComputeContraction(ref MeshPairContraction pair, MeshIndexTriangle[] indexTris, List <int>[] trisAttachedToVerts)
{
//This contains a list of all tris that will be changed by this contraction; boolean indicates whether they will be removed or not
Dictionary <int, bool> trisToChange = new Dictionary <int, bool>();
pair.deformedFaces.Clear();
pair.deletedFaces.Clear();
//Iterate through every triangle attached to vertex 0 of this pair and add them to the dict
foreach (int triIndex in trisAttachedToVerts[pair.v0])
{
if (indexTris[triIndex] != null)
{
trisToChange.Add(triIndex, false);
}
}
//Iterate through tris attached to vert 1...
foreach (int triIndex in trisAttachedToVerts[pair.v1])
{
if (indexTris[triIndex] == null)
{
continue;
}
//if the tri is already there, it will become degenerate during this contraction and should be removed
if (trisToChange.ContainsKey(triIndex))
{
trisToChange[triIndex] = true;
}
//else, add it and it will simply be deformed
else
{
trisToChange.Add(triIndex, false);
}
}
//Now, divide them into the appropriate lists
foreach (KeyValuePair <int, bool> triIndex in trisToChange)
{
if (triIndex.Value)
{
pair.deletedFaces.Add(triIndex.Key);
}
else
{
pair.deformedFaces.Add(triIndex.Key);
}
}
}
public static int DecimateVertices(int targetFaces, ref MinHeap <MeshPairContraction> pairContractions, ref Vector3[] verts, ref MeshIndexTriangle[] indexTris, ref List <int>[] trisAttachedToVerts, ref Quadric[] vertQuadrics)
{
int validFaces = indexTris.Length;
int counter = 1;
StringBuilder debug = new StringBuilder();
debug.AppendLine("Target Faces: " + targetFaces);
try
{
while (validFaces > targetFaces)
{
debug.AppendLine("Iteration: " + counter + " Faces: " + validFaces);
//Get the pair contraction with the least error associated with it
MeshPairContraction pair = pairContractions.ExtractDominating();
debug.AppendLine("Contraction between vertices at indicies: " + pair.v0 + " and " + pair.v1);
debug.AppendLine("Tris attached to v0: " + trisAttachedToVerts[pair.v0].Count + " Tris attached to v1: " + trisAttachedToVerts[pair.v1].Count);
//Get faces that will be deleted / changed by contraction
ComputeContraction(ref pair, indexTris, trisAttachedToVerts);
//Act on faces, delete extra vertex, change all references to second vertex
validFaces -= ApplyContraction(ref pair, ref pairContractions, ref verts, ref indexTris, ref trisAttachedToVerts, ref vertQuadrics);
counter++;
}
for (int i = 0; i < indexTris.Length; i++)
{
MeshIndexTriangle tri = indexTris[i];
if (tri == null)
{
continue;
}
if (trisAttachedToVerts[tri.v0] == null)
{
debug.AppendLine("Tri at index " + i + " points to nonexistent vertex at index " + tri.v0);
}
if (trisAttachedToVerts[tri.v1] == null)
{
debug.AppendLine("Tri at index " + i + " points to nonexistent vertex at index " + tri.v1);
}
if (trisAttachedToVerts[tri.v2] == null)
{
debug.AppendLine("Tri at index " + i + " points to nonexistent vertex at index " + tri.v2);
}
}
debug.AppendLine("Final: Faces: " + validFaces);
}
catch (Exception e)
{
debug.AppendLine("Error: " + e.Message);
debug.AppendLine("Stack trace");
debug.AppendLine(e.StackTrace);
}
Debug.Log(debug.ToString());
return(validFaces);
}
public static int ApplyContraction(ref MeshPairContraction pair, ref MinHeap <MeshPairContraction> pairContractions, ref Vector3[] verts, ref MeshIndexTriangle[] indexTris, ref List <int>[] trisAttachedToVerts, ref Quadric[] vertQuadrics)
{
int removedFaces = pair.deletedFaces.Count;
//Move v0, clear v1
verts[pair.v0] = pair.contractedPosition;
verts[pair.v1] = Vector3.zero;
foreach (int triIndex in trisAttachedToVerts[pair.v1])
{
if (!pair.deletedFaces.Contains(triIndex) && !trisAttachedToVerts[pair.v0].Contains(triIndex))
{
trisAttachedToVerts[pair.v0].Add(triIndex);
}
}
//Clear out all the tris attached to a non-existent vertex
trisAttachedToVerts[pair.v1] = null;
//Accumulate quadrics, clear unused one
vertQuadrics[pair.v0] += vertQuadrics[pair.v1];
vertQuadrics[pair.v1] = new Quadric();
//Adjust deformed triangles
foreach (int changedTri in pair.deformedFaces)
{
MeshIndexTriangle tri = indexTris[changedTri];
if (tri.v0.Equals(pair.v1))
{
tri.v0 = pair.v0;
}
else if (tri.v1.Equals(pair.v1))
{
tri.v1 = pair.v0;
}
else
{
tri.v2 = pair.v0;
}
indexTris[changedTri] = tri;
}
//Clear deleted triangles
foreach (int deletedTri in pair.deletedFaces)
{
indexTris[deletedTri] = null;
}
List <MeshPairContraction> pairList = pairContractions.ToList();
for (int i = 0; i < pairContractions.Count; i++)
{
MeshPairContraction otherPair = pairList[i];
if (otherPair.v0.Equals(pair.v1))
{
otherPair.v0 = pair.v0;
}
else if (otherPair.v1.Equals(pair.v1))
{
otherPair.v1 = pair.v0;
}
pairList[i] = otherPair;
}
int count = pairList.Count;
for (int i = 0; i < count; i++)
{
MeshPairContraction iItem = pairList[i];
for (int j = i + 1; j < count; j++)
{
if (pairList[j].Equals(iItem))
{
pairList.RemoveAt(j); //Remove duplicate element
count--; //Reduce length to iterate over
j--; //Make sure not to skip over a duplicate
}
}
if (iItem.v1 == iItem.v0)
{
pairList.RemoveAt(i); //Remove degenerate edge
count--; //Reduce length to iterate over
i--; //Make sure not to skip over a duplicate
continue;
}
CalculateTargetPositionForPairContraction(ref iItem, verts, vertQuadrics);
pairList[i] = iItem;
}
pairContractions = new MinHeap <MeshPairContraction>(pairList);
return(removedFaces);
}
