Thu, 12/05/2002 - 22:05

Forums:

Hi,

First of all, thanks Serge for the helpful reply to the last post !

Using the UV parameters for a surface, I would like the user to be able to move a vector along a U or V curve of a surface.

Can anyone please advise me on how to get a vector to latch the UV surface.

The second related question is - any idea of how to obtain the UV parametric co-ordinates at a point where my vector is on the UV surface.

Thanks a million,

Best regards,

Suds

Fri, 12/06/2002 - 15:14

Hi,

you can see the class "GeomLProp_SLProps" or

"BrepLProp_SLProps".

By the way, would you like to explain again, what means "move a vector along a U or V curve of a surface".

Regards,

Du

Mon, 12/09/2002 - 20:47

Du,

Thanks for your suggestions.

>you can see the class "GeomLProp_SLProps" or

"BrepLProp_SLProps".

I did use the U parameter of a curve to display a mid-point for selection in combination with the vertex selection filter. But I find it inefficient in comparison to the stock filters provided with OC. I wonder if the solution would be to create new filter classes. Would appreciate anyone's thoughts on if this would be the right way about it.

>By the way, would you like to explain again, what means "move a vector along a U or V curve of a surface".

Suppose we have the UV of a surface displayed, I want to use a unit vector to provide a positioning solution to any operation I may want to perform at any point on the surface. So, if I latch the vector onto the UV surface, then by moving the up/down, left/right keys, I step from one point to the next along the U or V curve. The user can re-set the UVs displayed according to a step size so that he can get the vector to the correct position. Then I can create a CAD object or operation aligned and postioned according to this vector.

I don't know if I've been able to convey the idea properly, but in modelling in 3D space, it would be easy for positioning new features, if we use a vector for locational & orientation information.

Cheers,

Suds

Wed, 12/11/2002 - 19:12

Hi, Suds,

I ve written a NC simulation based on UV parameters interrogation of sculptured surface ( but I m not sure, it is same as you :) ). The basic idea is: Compute the point on the surface, then get the relative curvature and principle direction, then using the gp_Trsf or Handle_Geom_Tranformation to translate the milling cutter. You get only the original coordinate of cutter (or Trihedron, vector) and the current direction, you can use the transformation in you own programs.

Regards,

Du