bool FKConvexElem::HullFromPlanes(const TArray<FPlane>& InPlanes, const TArray<FVector>& SnapVerts)
{
// Start by clearing this convex.
Reset();
float TotalPolyArea = 0;
for(int32 i=0; i<InPlanes.Num(); i++)
{
FPoly Polygon;
Polygon.Normal = InPlanes[i];
FVector AxisX, AxisY;
Polygon.Normal.FindBestAxisVectors(AxisX,AxisY);
const FVector Base = InPlanes[i] * InPlanes[i].W;
new(Polygon.Vertices) FVector(Base + AxisX * HALF_WORLD_MAX + AxisY * HALF_WORLD_MAX);
new(Polygon.Vertices) FVector(Base - AxisX * HALF_WORLD_MAX + AxisY * HALF_WORLD_MAX);
new(Polygon.Vertices) FVector(Base - AxisX * HALF_WORLD_MAX - AxisY * HALF_WORLD_MAX);
new(Polygon.Vertices) FVector(Base + AxisX * HALF_WORLD_MAX - AxisY * HALF_WORLD_MAX);
for(int32 j=0; j<InPlanes.Num(); j++)
{
if(i != j)
{
if(!Polygon.Split(-FVector(InPlanes[j]), InPlanes[j] * InPlanes[j].W))
{
Polygon.Vertices.Empty();
break;
}
}
}
// Do nothing if poly was completely clipped away.
if(Polygon.Vertices.Num() > 0)
{
TotalPolyArea += Polygon.Area();
// Add vertices of polygon to convex primitive.
for(int32 j=0; j<Polygon.Vertices.Num(); j++)
{
// We try and snap the vert to on of the ones supplied.
int32 NearestVert = INDEX_NONE;
float NearestDistSqr = BIG_NUMBER;
for(int32 k=0; k<SnapVerts.Num(); k++)
{
const float DistSquared = (Polygon.Vertices[j] - SnapVerts[k]).SizeSquared();
if( DistSquared < NearestDistSqr )
{
NearestVert = k;
NearestDistSqr = DistSquared;
}
}
// If we have found a suitably close vertex, use that
if( NearestVert != INDEX_NONE && NearestDistSqr < LOCAL_EPS )
{
const FVector localVert = SnapVerts[NearestVert];
AddVertexIfNotPresent(VertexData, localVert);
}
else
{
const FVector localVert = Polygon.Vertices[j];
AddVertexIfNotPresent(VertexData, localVert);
}
}
}
}
// If the collision volume isn't closed, return an error so the model can be discarded
if(TotalPolyArea < 0.001f)
{
UE_LOG(LogPhysics, Log, TEXT("Total Polygon Area invalid: %f"), TotalPolyArea );
return false;
}
// We need at least 4 vertices to make a convex hull with non-zero volume.
// We shouldn't have the same vertex multiple times (using AddVertexIfNotPresent above)
if(VertexData.Num() < 4)
{
return true;
}
// Check that not all vertices lie on a line (ie. find plane)
// Again, this should be a non-zero vector because we shouldn't have duplicate verts.
bool bFound = false;
FVector Dir2, Dir1;
Dir1 = VertexData[1] - VertexData[0];
Dir1.Normalize();
for(int32 i=2; i<VertexData.Num() && !bFound; i++)
{
Dir2 = VertexData[i] - VertexData[0];
Dir2.Normalize();
// If line are non-parallel, this vertex forms our plane
if((Dir1 | Dir2) < (1.f - LOCAL_EPS))
{
bFound = true;
}
}
if(!bFound)
{
return true;
}
// Now we check that not all vertices lie on a plane, by checking at least one lies off the plane we have formed.
FVector Normal = Dir1 ^ Dir2;
Normal.Normalize();
const FPlane Plane(VertexData[0], Normal);
bFound = false;
for(int32 i=2; i<VertexData.Num() ; i++)
{
if(Plane.PlaneDot(VertexData[i]) > LOCAL_EPS)
{
bFound = true;
break;
}
}
// If we did not find a vert off the line - discard this hull.
if(!bFound)
{
return true;
}
// calc bounding box of verts
UpdateElemBox();
// We can continue adding primitives (mesh is not horribly broken)
return true;
}
