// Split this Face with given Plane
public bool Split(Plane inPlane, out CSGFace outFront, out CSGFace outBack)
{
outFront = new CSGFace();
outBack = new CSGFace();
float[] distance = new float[vertices.Length + 1];
EPlaneSide[] side = new EPlaneSide[vertices.Length + 1];
for (int i = 0; i < vertices.Length; ++i)
{
distance[i] = inPlane.GetDistanceToPoint(vertices[i]);
side[i] = Side(inPlane, vertices[i]);
}
distance[vertices.Length] = distance[0];
side[vertices.Length] = side[0];
for (int i = 0; i < vertices.Length; ++i)
{
// if we lie on plane, add them to both
if (side[i] == EPlaneSide.Side_Planar)
{
outFront.AddVertex(vertices[i], uv[i]);
outBack.AddVertex(vertices[i], uv[i]);
// nothing todo with this vertex
continue;
}
// if we are on the front, add it to front face
if (side[i] == EPlaneSide.Side_Front)
{
outFront.AddVertex(vertices[i], uv[i]);
}
// if we are on the back, add it to the back side
else if (side[i] == EPlaneSide.Side_Back)
{
outBack.AddVertex(vertices[i], uv[i]);
}
// check if the next vertex is planar or on the same side, then we do not split
if (side[i + 1] == EPlaneSide.Side_Planar || side[i] == side[i + 1])
{
continue;
}
// create split point
Vector3 nextVector = vertices[(i + 1) % vertices.Length];
Vector2 nextUV = uv[(i + 1) % uv.Length];
Vector3 newVector, newUV;
// if we were on the front
if (side[i] == EPlaneSide.Side_Front)
{
float t = distance[i] / (distance[i] - distance[i + 1]);
newVector = vertices[i] + t * (nextVector - vertices[i]);
newUV = uv[i] + t * (nextUV - uv[i]);
}
else // back side...
{
float t = distance[i + 1] / (distance[i + 1] - distance[i]);
newVector = nextVector + t * (vertices[i] - nextVector);
newUV = nextUV + t * (uv[i] - nextUV);
}
// split points are added
// add to front
outFront.AddVertex(newVector, newUV);
// add to back
outBack.AddVertex(newVector, newUV);
}
// Debugging checks
if (outFront.vertices.Length < 3 || outBack.vertices.Length < 3)
{
Debug.Log("Degenerate Faces");
}
// todo...
outFront.material = material;
//
outBack.material = material;
return(true);
}
/// <summary>
/// Splits the face in a back and front part.
/// </summary>
/// <param name="face"></param>
/// <param name="splittingPlane"></param>
/// <returns></returns>
private EPlaneSide splitFaceByPlane(
Face face
, Plane splittingPlane
, out Face frontFace_, out Face backFace_
, float epsilon = 1e-3f//CLIP_EPSILON
)
{
var numVertices = face.vertices.Count;
var dists = new float[numVertices + 1];
var sides = new EPlaneSide[numVertices + 1];
// First, classify all points. This allows us to avoid any bisection if possible
var counts = new int[3]; // 'on', 'back' and 'front'
var faceStatus = (int)EPlaneSide.On;
// determine sides for each point
for (int i = 0; i < numVertices; i++)
{
var vertex = face.vertices[i];
var d = splittingPlane.GetDistanceToPoint(vertex);
dists[i] = d;
var side = (d > +epsilon)
? EPlaneSide.Front
: (d < -epsilon) ? EPlaneSide.Back : EPlaneSide.On;
sides[i] = side;
faceStatus |= (int)side;
counts[(int)side]++;
}
sides[numVertices] = sides[0];
dists[numVertices] = dists[0];
//
if (faceStatus != (int)EPlaneSide.Split)
{
backFace_ = face;
frontFace_ = face;
return((EPlaneSide)faceStatus);
}
Debug.DebugBreak();//AAA
// Straddles the splitting plane - we must clip.
//mxBIBREF("'float-Time Collision Detection' by Christer Ericson (2005), 8.3.4 Splitting Polygons Against a Plane, PP.369-373");
var MAX_VERTS = 32;
var backVerts = new Vector3[MAX_VERTS];
var frontVerts = new Vector3[MAX_VERTS];
var numFront = 0;
var numBack = 0;
// Test all edges (a, b) starting with edge from last to first Vector3
Vector3 vA = face.vertices[numVertices - 1];
float distA = dists[numVertices - 1];
EPlaneSide sideA = sides[numVertices - 1];
// Loop over all edges given by Vector3 pair (n - 1, n)
for (int i = 0; i < numVertices; i++)
{
Vector3 vB = face.vertices[i];
float distB = dists[i];
EPlaneSide sideB = sides[i];
if (sideB == EPlaneSide.Front)
{
if (sideA == EPlaneSide.Back)
{
// Edge (a, b) straddles, output intersection point to both sides
// always calculate the split going from the same side or minor epsilon issues can happen
Vector3 v = getIntersectionPoint(vB, vA, distB, distA);
Debug.Assert(classifyPoint(v, splittingPlane, epsilon) == EPlaneSide.On);
frontVerts[numFront++] = backVerts[numBack++] = v;
}
// In all three cases, output b to the front side
frontVerts[numFront++] = vB;
}
else if (sideB == EPlaneSide.Back)
{
if (sideA == EPlaneSide.Front)
{
// Edge (a, b) straddles plane, output intersection point
Vector3 v = getIntersectionPoint(vA, vB, distA, distB);
Debug.Assert(classifyPoint(v, splittingPlane, epsilon) == EPlaneSide.On);
frontVerts[numFront++] = backVerts[numBack++] = v;
}
else if (sideA == EPlaneSide.On)
{
// Output a when edge (a, b) goes from ‘on’ to ‘behind’ plane
backVerts[numBack++] = vA;
}
// In all three cases, output b to the back side
backVerts[numBack++] = vB;
}
else
{
// b is on the plane. In all three cases output b to the front side
frontVerts[numFront++] = vB;
// In one case, also output b to back side
if (sideA == EPlaneSide.Back)
{
backVerts[numBack++] = vB;
}
}
// Keep b as the starting point of the next edge
vA = vB;
distA = distB;
sideA = sideB;
}
//
frontFace_ = new Face();
frontFace_.vertices = frontVerts.ToList();
backFace_ = new Face();
backFace_.vertices = backVerts.ToList();
Debug.Assert(faceStatus == (int)EPlaneSide.Split);
return(EPlaneSide.Split);
}
// Split this Face with given Plane
public bool Split( Plane inPlane, out Face outFront, out Face outBack )
{
outFront = new Face();
outBack = new Face();
float[] distance = new float[vertices.Length + 1];
EPlaneSide[] side = new EPlaneSide[vertices.Length + 1];
for( int i = 0; i < vertices.Length; ++i )
{
distance[i] = inPlane.GetDistanceToPoint( vertices[i] );
side[i] = Side( inPlane, vertices[i] );
}
distance[vertices.Length] = distance[0];
side[vertices.Length] = side[0];
for( int i = 0; i < vertices.Length; ++i )
{
// if we lie on plane, add them to both
if( side[i] == EPlaneSide.Side_Planar )
{
outFront.AddVertex( vertices[i], uv[i] );
outBack.AddVertex( vertices[i], uv[i] );
// nothing todo with this vertex
continue;
}
// if we are on the front, add it to front face
if( side[i] == EPlaneSide.Side_Front )
{
outFront.AddVertex( vertices[i], uv[i] );
}
// if we are on the back, add it to the back side
else if( side[i] == EPlaneSide.Side_Back )
{
outBack.AddVertex( vertices[i], uv[i] );
}
// check if the next vertex is planar or on the same side, then we do not split
if( side[i+1] == EPlaneSide.Side_Planar || side[i] == side[i+1] )
continue;
// create split point
Vector3 nextVector = vertices[ (i+1) % vertices.Length];
Vector2 nextUV = uv[ (i+1) % uv.Length];
Vector3 newVector, newUV;
// if we were on the front
if( side[i] == EPlaneSide.Side_Front )
{
float t = distance[i] / (distance[i] - distance[i+1]);
newVector = vertices[i] + t * (nextVector - vertices[i]);
newUV = uv[i] + t * (nextUV - uv[i]);
}
else // back side...
{
float t = distance[i+1] / (distance[i+1] - distance[i]);
newVector = nextVector + t * (vertices[i] - nextVector);
newUV = nextUV + t * (uv[i] - nextUV);
}
// split points are added
// add to front
outFront.AddVertex( newVector, newUV );
// add to back
outBack.AddVertex( newVector, newUV );
}
// Debugging checks
if( outFront.vertices.Length < 3 || outBack.vertices.Length < 3 )
Debug.Log("Degenerate Faces");
// todo...
outFront.material = material;
//
outBack.material = material;
return true;
}
