/*
* Cuts the given object using the provided NDPlane. This function returns a List of Meshes
* which is the final mesh cut by the NDPlane. At most, this function will return 2 meshes.
*/
public static List <Mesh> CutObject(GameObject obj, NDPlane plane)
{
List <Mesh> newMeshes = new List <Mesh>();
if (plane == null)
{
return(newMeshes);
}
MeshFilter renderer = obj.GetComponent <MeshFilter>();
if (renderer == null)
{
return(newMeshes);
}
Mesh sharedMesh = renderer.sharedMesh;
if (sharedMesh == null)
{
return(newMeshes);
}
Vector3[] vertices = sharedMesh.vertices;
Vector2[] uv = sharedMesh.uv;
int[] indices = sharedMesh.triangles;
// the primary buffers which will be used to construct a new mesh
List <Vector3> upperHull = new List <Vector3>();
List <Vector3> lowerHull = new List <Vector3>();
List <int> upperIndices = new List <int>();
List <int> lowerIndices = new List <int>();
List <Vector2> upperUV = new List <Vector2>();
List <Vector2> lowerUV = new List <Vector2>();
List <Vector3> closingHull = new List <Vector3>();
List <Vector2> closingHullUV = new List <Vector2>();
List <int> closingHullIndices = new List <int>();
int indicesCount = indices.Length;
for (int index = 0; index < indicesCount; index += 3)
{
// get the first triangles
Vector3 tri1 = vertices[indices[index]];
Vector3 tri2 = vertices[indices[index + 1]];
Vector3 tri3 = vertices[indices[index + 2]];
// get the first triangle UV's
Vector2 tri1uva = uv[indices[index]];
Vector2 tri1uvb = uv[indices[index + 1]];
Vector2 tri1uvc = uv[indices[index + 2]];
// clear our temporary Buffers
tmpLowerHull.Clear();
tmpUpperHull.Clear();
tmpIntersectionPt.Clear();
tmpIntersectionUv.Clear();
tmpLowerHullUV.Clear();
tmpUpperHullUV.Clear();
tmpLowerIndices.Clear();
tmpUpperIndices.Clear();
// intersect the first triangle
plane.IntersectTriangleHull(ref tri1,
ref tri2,
ref tri3,
ref tri1uva,
ref tri1uvb,
ref tri1uvc,
tmpLowerHull,
tmpLowerHullUV,
tmpUpperHull,
tmpUpperHullUV,
tmpIntersectionPt,
tmpIntersectionUv);
// add intersection point into overall buffers
tmpLowerHull.AddRange(tmpIntersectionPt);
tmpUpperHull.AddRange(tmpIntersectionPt);
tmpLowerHullUV.AddRange(tmpIntersectionUv);
tmpUpperHullUV.AddRange(tmpIntersectionUv);
closingHull.AddRange(tmpIntersectionPt);
// triangulate the temporary buffers and get the indices
Triangulator.TriangulateNDSlice(tmpLowerHull, tmpLowerIndices, lowerHull.Count);
Triangulator.TriangulateNDSlice(tmpUpperHull, tmpUpperIndices, upperHull.Count);
// add to the final buffers
upperHull.AddRange(tmpUpperHull);
lowerHull.AddRange(tmpLowerHull);
upperIndices.AddRange(tmpUpperIndices);
lowerIndices.AddRange(tmpLowerIndices);
upperUV.AddRange(tmpUpperHullUV);
lowerUV.AddRange(tmpLowerHullUV);
}
List <Vector3> finalClosingHull = new List <Vector3>();
// generate the closing hull (if any)
if (closingHull.Count > 0)
{
Triangulator.TriangulateHullPt(closingHull, finalClosingHull, closingHullIndices, closingHullUV, plane.Normal);
}
if (upperIndices.Count > 0)
{
Mesh newMesh = new Mesh();
newMesh.subMeshCount = 2;
// close the hull
int count = upperHull.Count;
upperHull.AddRange(finalClosingHull);
upperUV.AddRange(closingHullUV);
newMesh.SetVertices(upperHull);
newMesh.SetTriangles(upperIndices, 0);
newMesh.SetUVs(0, upperUV);
// set the closing hull UV's
int triCount = closingHullIndices.Count;
if (triCount > 0)
{
List <int> finalTriangles = new List <int>();
for (int i = 0; i < triCount; i += 3)
{
finalTriangles.Add(closingHullIndices[i] + count);
finalTriangles.Add(closingHullIndices[i + 2] + count);
finalTriangles.Add(closingHullIndices[i + 1] + count);
}
newMesh.SetTriangles(finalTriangles, 1);
}
newMesh.RecalculateNormals();
newMeshes.Add(newMesh);
}
if (lowerIndices.Count > 0)
{
Mesh newMesh = new Mesh();
newMesh.subMeshCount = 2;
// close the hull
int count = lowerHull.Count;
lowerHull.AddRange(finalClosingHull);
lowerUV.AddRange(closingHullUV);
newMesh.SetVertices(lowerHull);
newMesh.SetTriangles(lowerIndices, 0);
newMesh.SetUVs(0, lowerUV);
// set the closing hull UV's
int triCount = closingHullIndices.Count;
if (triCount > 0)
{
List <int> finalTriangles = new List <int>();
for (int i = 0; i < triCount; i += 3)
{
finalTriangles.Add(closingHullIndices[i] + count);
finalTriangles.Add(closingHullIndices[i + 1] + count);
finalTriangles.Add(closingHullIndices[i + 2] + count);
}
newMesh.SetTriangles(finalTriangles, 1);
}
newMesh.RecalculateNormals();
newMeshes.Add(newMesh);
}
return(newMeshes);
}
