// Slice mesh along plane intersection
public static void SliceMesh(GameObject obj, CustomPlane plane, bool isConvex)
{
// original GameObject data
Transform objTransform = obj.transform;
Mesh objMesh = obj.GetComponent<MeshFilter>().mesh;
Vector3[] meshVerts = objMesh.vertices;
int[] meshTris = objMesh.triangles;
Vector2[] meshUVs = objMesh.uv;
// Slice mesh data
slice1Verts = new List<Vector3>();
slice2Verts = new List<Vector3>();
slice1Tris = new List<int>();
slice2Tris = new List<int>();
slice1UVs = new List<Vector2>();
slice2UVs = new List<Vector2>();
lineLoop = new List<Line>();
// Loop through triangles
for(int i = 0; i < meshTris.Length / 3; i++) {
// Define triangle
Vector3[] triVertsLocal = new Vector3[3];
Vector3[] triVertsWorld = new Vector3[3];
Vector2[] triUVs = new Vector2[3];
for(int j = 0; j < 3; j++) {
int meshIndexor = (i + 1) * 3 - (3 - j);
triVertsLocal[j] = meshVerts[meshTris[meshIndexor]]; // local model space vertices
triVertsWorld[j] = objTransform.TransformPoint(triVertsLocal[j]); // world space vertices
triUVs[j] = meshUVs[meshTris[meshIndexor]]; // original uv coordinates
}
// Side test: (0) = intersecting plane; (+) = above plane; (-) = below plane;
float vert1Side = plane.GetSide(triVertsWorld[0]);
float vert2Side = plane.GetSide(triVertsWorld[1]);
float vert3Side = plane.GetSide(triVertsWorld[2]);
// assign triangles that do not intersect plane
if(vert1Side > 0 && vert2Side > 0 && vert3Side > 0) { // Slice 1
for(int j = 0; j < triVertsLocal.Length; j++) {
slice1Verts.Add(triVertsLocal[j]);
slice1Tris.Add(slice1Verts.Count - 1);
slice1UVs.Add(triUVs[j]);
}
} else if(vert1Side < 0 && vert2Side < 0 && vert3Side < 0) { // Slice 2
for(int j = 0; j < triVertsLocal.Length; j++) {
slice2Verts.Add(triVertsLocal[j]);
slice2Tris.Add(slice2Verts.Count - 1);
slice2UVs.Add(triUVs[j]);
}
} else if(vert1Side == 0 || vert2Side == 0 || vert3Side == 0) {
Debug.Log ("Point-Plane Intersection");
return;
} else { // Intersecting Triangles
Vector3[] slicedTriVerts = new Vector3[5];
Vector2[] slicedTriUVs = new Vector2[5];
Vector3[] triVertsWorld2 = new Vector3[3];
int[] vertOrder; // triangle vertex-order CW vs. CCW
if(vert1Side * vert2Side > 0) {
int[] triOrder = {2,0,1};
for(int j = 0; j < triOrder.Length; j++) {
slicedTriVerts[j] = triVertsLocal[triOrder[j]];
slicedTriUVs[j] = triUVs[triOrder[j]];
triVertsWorld2[j] = triVertsWorld[triOrder[j]];
}
vertOrder = vertOrderCW;
} else if(vert1Side * vert3Side > 0) {
int[] triOrder = {1,0,2};
for(int j = 0; j < triOrder.Length; j++) {
slicedTriVerts[j] = triVertsLocal[triOrder[j]];
slicedTriUVs[j] = triUVs[triOrder[j]];
triVertsWorld2[j] = triVertsWorld[triOrder[j]];
}
vertOrder = vertOrderCCW;
} else {
int[] triOrder = {0,1,2};
for(int j = 0; j < triOrder.Length; j++) {
slicedTriVerts[j] = triVertsLocal[triOrder[j]];
slicedTriUVs[j] = triUVs[triOrder[j]];
triVertsWorld2[j] = triVertsWorld[triOrder[j]];
}
vertOrder = vertOrderCW;
}
// Points of Intersection
Vector3 poi1 = plane.VectorPlanePOI(triVertsWorld2[0], (triVertsWorld2[1] - triVertsWorld2[0]).normalized);
Vector3 poi2 = plane.VectorPlanePOI(triVertsWorld2[0], (triVertsWorld2[2] - triVertsWorld2[0]).normalized);
slicedTriVerts[3] = objTransform.InverseTransformPoint(poi1);
slicedTriVerts[4] = objTransform.InverseTransformPoint(poi2);
lineLoop.Add(new Line(slicedTriVerts[3], slicedTriVerts[4], poi1, poi2));
// POI UVs
float t1 = Vector3.Distance(slicedTriVerts[0], slicedTriVerts[3]) / Vector3.Distance(slicedTriVerts[0], slicedTriVerts[1]);
float t2 = Vector3.Distance(slicedTriVerts[0], slicedTriVerts[4]) / Vector3.Distance(slicedTriVerts[0], slicedTriVerts[2]);
slicedTriUVs[3] = Vector2.Lerp(slicedTriUVs[0], slicedTriUVs[1], t1);
slicedTriUVs[4] = Vector2.Lerp(slicedTriUVs[0], slicedTriUVs[2], t2);
// Add bisected triangle to slice respectively
if(plane.GetSide(triVertsWorld2[0]) > 0) {
// Slice 1
for(int j = 0; j < 3; j++) {
slice1Verts.Add(slicedTriVerts[vertOrder[j]]);
slice1Tris.Add(slice1Verts.Count - 1);
slice1UVs.Add(slicedTriUVs[vertOrder[j]]);
}
// Slice 2
for(int j = 3; j < 9; j++) {
slice2Verts.Add(slicedTriVerts[vertOrder[j]]);
slice2Tris.Add(slice2Verts.Count - 1);
slice2UVs.Add(slicedTriUVs[vertOrder[j]]);
}
} else {
// Slice 2
for(int j = 0; j < 3; j++) {
slice2Verts.Add(slicedTriVerts[vertOrder[j]]);
slice2Tris.Add(slice2Verts.Count - 1);
slice2UVs.Add(slicedTriUVs[vertOrder[j]]);
}
// Slice 1
for(int j = 3; j < 9; j++) {
slice1Verts.Add(slicedTriVerts[vertOrder[j]]);
slice1Tris.Add(slice1Verts.Count - 1);
slice1UVs.Add(slicedTriUVs[vertOrder[j]]);
}
}
}
}
if(lineLoop.Count > 0) {
// Fill convex mesh
if(isConvex) {
Vector3 normal = plane.normal;
do {
Polygon polygon = new Polygon(lineLoop, normal);
Vector3 polygonNormal = (polygon.isClockWise) ? normal : -normal;
TriangulatePolygon(polygon.edges, polygonNormal, polygon.isClockWise);
} while(lineLoop.Count != 0);
}
// Build Meshes
if(slice1Verts.Count > 0) {
BuildSlice(obj, objTransform, slice1Verts.ToArray(), slice1Tris.ToArray(), slice1UVs.ToArray());
}
if(slice2Verts.Count > 0) {
BuildSlice(obj, objTransform, slice2Verts.ToArray(), slice2Tris.ToArray(), slice2UVs.ToArray());
}
// Delete original
GameObject.Destroy(obj);
}
}
// Slice mesh along plane intersection
public static void SliceMesh(GameObject obj, CustomPlane plane, bool isConvex)
{
// original GameObject data
Transform objTransform = obj.transform;
Mesh objMesh = obj.GetComponent <MeshFilter>().mesh;
Vector3[] meshVerts = objMesh.vertices;
int[] meshTris = objMesh.triangles;
Vector2[] meshUVs = objMesh.uv;
// Slice mesh data
slice1Verts = new List <Vector3>();
slice2Verts = new List <Vector3>();
slice1Tris = new List <int>();
slice2Tris = new List <int>();
slice1UVs = new List <Vector2>();
slice2UVs = new List <Vector2>();
lineLoop = new List <Line>();
// Loop through triangles
for (int i = 0; i < meshTris.Length / 3; i++)
{
// Define triangle
Vector3[] triVertsLocal = new Vector3[3];
Vector3[] triVertsWorld = new Vector3[3];
Vector2[] triUVs = new Vector2[3];
for (int j = 0; j < 3; j++)
{
int meshIndexor = (i + 1) * 3 - (3 - j);
triVertsLocal[j] = meshVerts[meshTris[meshIndexor]]; // local model space vertices
triVertsWorld[j] = objTransform.TransformPoint(triVertsLocal[j]); // world space vertices
triUVs[j] = meshUVs[meshTris[meshIndexor]]; // original uv coordinates
}
// Side test: (0) = intersecting plane; (+) = above plane; (-) = below plane;
float vert1Side = plane.GetSide(triVertsWorld[0]);
float vert2Side = plane.GetSide(triVertsWorld[1]);
float vert3Side = plane.GetSide(triVertsWorld[2]);
// assign triangles that do not intersect plane
if (vert1Side > 0 && vert2Side > 0 && vert3Side > 0) // Slice 1
{
for (int j = 0; j < triVertsLocal.Length; j++)
{
slice1Verts.Add(triVertsLocal[j]);
slice1Tris.Add(slice1Verts.Count - 1);
slice1UVs.Add(triUVs[j]);
}
}
else if (vert1Side < 0 && vert2Side < 0 && vert3Side < 0) // Slice 2
{
for (int j = 0; j < triVertsLocal.Length; j++)
{
slice2Verts.Add(triVertsLocal[j]);
slice2Tris.Add(slice2Verts.Count - 1);
slice2UVs.Add(triUVs[j]);
}
}
else if (vert1Side == 0 || vert2Side == 0 || vert3Side == 0)
{
Debug.Log("Point-Plane Intersection");
return;
}
else // Intersecting Triangles
{
Vector3[] slicedTriVerts = new Vector3[5];
Vector2[] slicedTriUVs = new Vector2[5];
Vector3[] triVertsWorld2 = new Vector3[3];
int[] vertOrder; // triangle vertex-order CW vs. CCW
if (vert1Side * vert2Side > 0)
{
int[] triOrder = { 2, 0, 1 };
for (int j = 0; j < triOrder.Length; j++)
{
slicedTriVerts[j] = triVertsLocal[triOrder[j]];
slicedTriUVs[j] = triUVs[triOrder[j]];
triVertsWorld2[j] = triVertsWorld[triOrder[j]];
}
vertOrder = vertOrderCW;
}
else if (vert1Side * vert3Side > 0)
{
int[] triOrder = { 1, 0, 2 };
for (int j = 0; j < triOrder.Length; j++)
{
slicedTriVerts[j] = triVertsLocal[triOrder[j]];
slicedTriUVs[j] = triUVs[triOrder[j]];
triVertsWorld2[j] = triVertsWorld[triOrder[j]];
}
vertOrder = vertOrderCCW;
}
else
{
int[] triOrder = { 0, 1, 2 };
for (int j = 0; j < triOrder.Length; j++)
{
slicedTriVerts[j] = triVertsLocal[triOrder[j]];
slicedTriUVs[j] = triUVs[triOrder[j]];
triVertsWorld2[j] = triVertsWorld[triOrder[j]];
}
vertOrder = vertOrderCW;
}
// Points of Intersection
Vector3 poi1 = plane.VectorPlanePOI(triVertsWorld2[0], (triVertsWorld2[1] - triVertsWorld2[0]).normalized);
Vector3 poi2 = plane.VectorPlanePOI(triVertsWorld2[0], (triVertsWorld2[2] - triVertsWorld2[0]).normalized);
slicedTriVerts[3] = objTransform.InverseTransformPoint(poi1);
slicedTriVerts[4] = objTransform.InverseTransformPoint(poi2);
lineLoop.Add(new Line(slicedTriVerts[3], slicedTriVerts[4], poi1, poi2));
// POI UVs
float t1 = Vector3.Distance(slicedTriVerts[0], slicedTriVerts[3]) / Vector3.Distance(slicedTriVerts[0], slicedTriVerts[1]);
float t2 = Vector3.Distance(slicedTriVerts[0], slicedTriVerts[4]) / Vector3.Distance(slicedTriVerts[0], slicedTriVerts[2]);
slicedTriUVs[3] = Vector2.Lerp(slicedTriUVs[0], slicedTriUVs[1], t1);
slicedTriUVs[4] = Vector2.Lerp(slicedTriUVs[0], slicedTriUVs[2], t2);
// Add bisected triangle to slice respectively
if (plane.GetSide(triVertsWorld2[0]) > 0)
{
// Slice 1
for (int j = 0; j < 3; j++)
{
slice1Verts.Add(slicedTriVerts[vertOrder[j]]);
slice1Tris.Add(slice1Verts.Count - 1);
slice1UVs.Add(slicedTriUVs[vertOrder[j]]);
}
// Slice 2
for (int j = 3; j < 9; j++)
{
slice2Verts.Add(slicedTriVerts[vertOrder[j]]);
slice2Tris.Add(slice2Verts.Count - 1);
slice2UVs.Add(slicedTriUVs[vertOrder[j]]);
}
}
else
{
// Slice 2
for (int j = 0; j < 3; j++)
{
slice2Verts.Add(slicedTriVerts[vertOrder[j]]);
slice2Tris.Add(slice2Verts.Count - 1);
slice2UVs.Add(slicedTriUVs[vertOrder[j]]);
}
// Slice 1
for (int j = 3; j < 9; j++)
{
slice1Verts.Add(slicedTriVerts[vertOrder[j]]);
slice1Tris.Add(slice1Verts.Count - 1);
slice1UVs.Add(slicedTriUVs[vertOrder[j]]);
}
}
}
}
if (lineLoop.Count > 0)
{
// Fill convex mesh
if (isConvex)
{
Vector3 normal = plane.normal;
do
{
Polygon polygon = new Polygon(lineLoop, normal);
Vector3 polygonNormal = (polygon.isClockWise) ? normal : -normal;
TriangulatePolygon(polygon.edges, polygonNormal, polygon.isClockWise);
} while(lineLoop.Count != 0);
}
// Build Meshes
if (slice1Verts.Count > 0)
{
BuildSlice(obj, objTransform, slice1Verts.ToArray(), slice1Tris.ToArray(), slice1UVs.ToArray());
}
if (slice2Verts.Count > 0)
{
BuildSlice(obj, objTransform, slice2Verts.ToArray(), slice2Tris.ToArray(), slice2UVs.ToArray());
}
// Delete original
GameObject.Destroy(obj);
}
}
