/**
* Slice the gameobject mesh (if any) using the Plane, which will generate
* a maximum of 2 other Meshes.
* This function will recalculate new UV coordinates to ensure textures are applied
* properly.
* Returns null if no intersection has been found or the GameObject does not contain
* a valid mesh to cut.
*/
public static SlicedHull Slice(Mesh sharedMesh, Plane pl, TextureRegion region, int crossIndex)
{
if (sharedMesh == null)
{
return(null);
}
SlicedMeshDetails sliceDetails = SliceMesh(sharedMesh, pl);
// check if slicing actually occured
for (int i = 0; i < sliceDetails.slices.Length; i++)
{
// check if at least one of the submeshes was sliced. If so, stop checking
// because we need to go through the generation step
if (sliceDetails.slices[i] != null && sliceDetails.slices[i].isValid)
{
return(CreateFrom(sliceDetails.slices, CreateFrom(sliceDetails.crossHull, pl.normal, region), crossIndex));
}
}
// no slicing occured, just return null to signify
return(null);
}
private static List <Vector3> EdgeLoop(Mesh sharedMesh, Plane pl)
{
if (sharedMesh == null)
{
return(null);
}
SlicedMeshDetails sliceDetails = SliceMesh(sharedMesh, pl);
// check if slicing actually occured
for (int i = 0; i < sliceDetails.slices.Length; i++)
{
// check if at least one of the submeshes was sliced. If so, stop checking
// because we need to go through the generation step
if (sliceDetails.slices[i] != null && sliceDetails.slices[i].isValid)
{
return(sliceDetails.crossHull);
}
}
// no slicing occured, just return null to signify
return(null);
}
/**
* Slice the mesh, and return sliced mesh details
**/
private static SlicedMeshDetails SliceMesh(Mesh sharedMesh, Plane pl)
{
SlicedMeshDetails details = new SlicedMeshDetails();
Vector3[] verts = sharedMesh.vertices;
Vector2[] uv = sharedMesh.uv;
Vector3[] norm = sharedMesh.normals;
Vector4[] tan = sharedMesh.tangents;
int submeshCount = sharedMesh.subMeshCount;
// each submesh will be sliced and placed in its own array structure
SlicedSubmesh[] slices = new SlicedSubmesh[submeshCount];
// the cross section hull is common across all submeshes
List <Vector3> crossHull = new List <Vector3>();
// we reuse this object for all intersection tests
IntersectionResult result = new IntersectionResult();
// see if we would like to split the mesh using uv, normals and tangents
bool genUV = verts.Length == uv.Length;
bool genNorm = verts.Length == norm.Length;
bool genTan = verts.Length == tan.Length;
// iterate over all the submeshes individually. vertices and indices
// are all shared within the submesh
for (int submesh = 0; submesh < submeshCount; submesh++)
{
int[] indices = sharedMesh.GetTriangles(submesh);
int indicesCount = indices.Length;
SlicedSubmesh mesh = new SlicedSubmesh();
// loop through all the mesh vertices, generating upper and lower hulls
// and all intersection points
for (int index = 0; index < indicesCount; index += 3)
{
int i0 = indices[index + 0];
int i1 = indices[index + 1];
int i2 = indices[index + 2];
Triangle newTri = new Triangle(verts[i0], verts[i1], verts[i2]);
// generate UV if available
if (genUV)
{
newTri.SetUV(uv[i0], uv[i1], uv[i2]);
}
// generate normals if available
if (genNorm)
{
newTri.SetNormal(norm[i0], norm[i1], norm[i2]);
}
// generate tangents if available
if (genTan)
{
newTri.SetTangent(tan[i0], tan[i1], tan[i2]);
}
// slice this particular triangle with the provided
// plane
if (newTri.Split(pl, result))
{
int upperHullCount = result.upperHullCount;
int lowerHullCount = result.lowerHullCount;
int interHullCount = result.intersectionPointCount;
for (int i = 0; i < upperHullCount; i++)
{
mesh.upperHull.Add(result.upperHull[i]);
}
for (int i = 0; i < lowerHullCount; i++)
{
mesh.lowerHull.Add(result.lowerHull[i]);
}
for (int i = 0; i < interHullCount; i++)
{
crossHull.Add(result.intersectionPoints[i]);
}
}
else
{
SideOfPlane side = pl.SideOf(verts[i0]);
if (side == SideOfPlane.UP || side == SideOfPlane.ON)
{
mesh.upperHull.Add(newTri);
}
else
{
mesh.lowerHull.Add(newTri);
}
}
}
// register into the index
slices[submesh] = mesh;
}
details.slices = slices;
details.crossHull = crossHull;
return(details);
}
