Hello again
I've an xref which is an exploded polyface mesh so it consists of triangular faces. I am writing code to calculate levels on a line using the triangles in the mesh. I've written one version which works but which was slow - for every point in the polyline it looked through every triangle in the mesh until it found which triangle the point was in then interpolated the level. So I thought I could speed it up by reducing the number of triangles to loop through by finding which ones cut the polyline and then I only have to loop through these. Problem is that my code doesn't work - it says every triangle in the mesh intersects with the line.
Code follows (this is just the bit to find to filter the triangles, not the interpolation bits):
Sub LevelFromTria2()
Dim objPLine As AcadLWPolyline
Dim objTria As Acad3DFace
Dim varCoords As Variant '
Dim objBlock As AcadBlock
Dim lngCount As Long
Dim objTriaSides As AcadLWPolyline
Dim varIntPoints As Variant
Dim dblTriaSidesCoords(0 To 5) As Double
Dim varPnt As Variant
On Error Resume Next '* Do so that if layer exists no error
ThisDrawing.Layers.Add ("Temp Triangles")
On Error GoTo 0
ThisDrawing.Utility.GetEntity objPLine, varPnt, "Select polyline: "
Set objBlock = ThisDrawing.Blocks("draw tria exploded")
'* Go through all the items in the xref
For lngCount = 0 To objBlock.Count - 1
'* See if the item is a 3d face
If objBlock.Item(lngCount).ObjectName = "AcDbFace" Then
'* If it is get the face element
Set objTria = objBlock.Item(lngCount)
'* See if the face intersects with the polyline
varIntPoints = objTria.IntersectWith(objPLine, acExtendNone)
'* If it does, draw the triangle - TEMP MEASURE TO SEE IF IT IS FINDING THE RIGHT TRIANGLES
If VarType(varIntPoints) <> vbEmpty Then
'* Get co-ords of the 3d face
varCoords = objTria.Coordinates
'* Set up 2d coords for the triangle edge
dblTriaSidesCoords(0) = varCoords(0)
dblTriaSidesCoords(1) = varCoords(1)
dblTriaSidesCoords(2) = varCoords(3)
dblTriaSidesCoords(3) = varCoords(4)
dblTriaSidesCoords(4) = varCoords(6)
dblTriaSidesCoords(5) = varCoords(7)
'* Add a LW polyline to show the triangle which intersects with the polyline
Set objTriaSides = ThisDrawing.ModelSpace.AddLightWeightPolyline(dblTriaSidesCoords)
objTriaSides.Closed = True
objTriaSides.Layer = "Temp Triangles"
objTriaSides.color = acMagenta
objTriaSides.Update
End If
End If
Next lngCount
End Sub
Attached is the drawing I am testing this on. The line I am trying to get levels on is the yellow line - so pick this when prompted.
I'm thinking I've got something wrong with the intersect method. Rather than using the face itself I've also tried making a LW polyline from it and that doesn't work either.
Any suggestions as to how to get the above to work would be much appreciated. (Or if you have another concept for speeding up the way it gets levels onto the line from the triangulation I'd be interested to hear that too!)
Thanks
Jon
