Get Gradient At Projected Point On Surface Edge    

This command offsets an edge point in the specified direction, then projects a point onto the selected surface. The surface U direction is determined here, then the point is projected back to the reference B-Spline. The command returns the normal vector of the surface as well as the U and V direction vectors of the surface at the projected point on the spline. The edge offset avoids ambiguous surface UV directions directly on the surface edge.

 

Input Arguments

 

0

Point Name

Point to Project

Reference point (on b-spline) used for analysis.

1

Collection Object Name

B-Spline Name

Reference B-Spline from Surface edge used for projection.

2

Collection Object Name

Surface Name

Reference Surface used for projection.

3

Vector

Edge Offset Direction

Working direction to offset Point to Project such that it will intersect the surface.

4

Double

Edge Offset Distance

Distance to offset the Point to Project such that it

will intersect the surface.

3

Boolean

Generate output vector lines?

Option to construct lines defining the surface vec- tor at the point projection.

 

Return Arguments

 

3

Vector

Projected Point

XYZ location of the projected Point

4

Vector

Normal Vector

Normal vector for the surface direction at the projected point

5

Vector

U Direction

The U direction vector at the projected point

6

Vector

V Direction

The V direction vector at the projected point

 

Returned Status

 

SUCCESS

The point was projected successfully and direction vectors obtained

FAILURE

No point or surfaces could be found, or the point was projected to the surface edge after offsetting (try changing Edge Offset Distance).

 

Remarks

If Argument 3 is True, three lines will be created. The names of the lines will be based on the point name from Argu- ment 0; [Collection]_[Group]_[Target] Projected [Direction Description], where [Direction Description] is Normal, U-Direction, or V-Direction.

All vectors returned are in the working frame.

The input point is likely generated by laying out points on the surface edge spline. The input point is first offset along the Edge Offset Direction by the Edge Offset Distance, then it is projected to the surface to find the U and V surface directions. This projected point is further projected along the V direction back to the B-Spline. This results in the

 

returned Projected Point being different than the Point to Project, and the U-direction is only approximate as deter- mined at the offset point projected onto the surface. The Normal vector will be correct relative to the V-direction at the returned point on the B-Spline, but will be approximate relative to the B-Spline in the U-direction.