Point - direction type line
Point - direction type line
(OP)
Could you please explain how this is done by CATIA?
1. There is surface (S) and a point (P) on it. Also a line (L) that goes through the point (P).
2. In command line - point-direction type, select inputs above such that the surface (S) is the support and the line (L) is the direction...
3. Finally will be a computed curve on the supprot. But how is this curve made by CATIA? This is not made by a projection.
1. There is surface (S) and a point (P) on it. Also a line (L) that goes through the point (P).
2. In command line - point-direction type, select inputs above such that the surface (S) is the support and the line (L) is the direction...
3. Finally will be a computed curve on the supprot. But how is this curve made by CATIA? This is not made by a projection.





RE: Point - direction type line
Are you referring to a line normal (perpendicular) to a surface through a point?
My other question is whether you ask for the mathematics behind the generation of the line normal to a surface, or the methodology in CATIA to achieve that?
CATIA v5 — user & trainer
ANSYS — user (beginner)
RE: Point - direction type line
Thanks for your care about the subject.
Not normal, the line is used as the direction and would have any component of x, y, z.
Actuallay I'd like to know the methodoloy to achieve the computed curve on the surface.
RE: Point - direction type line
S(x,y,z)=0
It can also be described as S(x,y,z)=f(x,y)-z=0
thus:
z=f(x,y)
so the parapendicular vector can be described as below:
n^=[df/dx,df/dy,1]*lambda
where
d/dx - partial differention
lambda - variable (used to normalize lenght of vector)
For specified point You need find values of those differentions
LukaszSz. Poland, Warsaw University of Technology, Faculty of Power and Aeronautical Engineering : MEchanical Engineering. BsC - 2013
RE: Point - direction type line
RE: Point - direction type line
If Yours part is not large (doesn't contain lot of surfaces) You can do loop through all surfaces and check if oSurface (as below) is same as one of the listed surfaces
here is the example code
(as input select surface)
CODE -->
anyway, bolded condition isn't working for me so i'm comparising names
LukaszSz. Poland, Warsaw University of Technology, Faculty of Power and Aeronautical Engineering : MEchanical Engineering. BsC - 2013
RE: Point - direction type line
Thank you but I'm not researching about how the normal vector is computed at a point on surface. I'm just researching which way the laid down curve on the surfac support is achieved, when using a point-direction line but with a surface support.
@ TibiX
You know, to know how CATIA works is my aim. I'm not running into a trouble in a design.
Not bad have a look here:
http://www.3dcadforums.com/catia-forum/6831-surfac...
RE: Point - direction type line
vector L (x,y,z) from line is projected on surface as vector L'(u,v) at point O, line passing by point O on support is define by all point P on S with OP = K x L'
What I noticed:
on a cylinder surface S I create point P
at P I create a line L1 with a compass direction
then I create line L2 on support S with direction L1
using develop I bring L2 on a plane and when I analyze it, it is a line.
if I project L1 on S I have P1, when I develop P1 (as I did with L2), the result is a curve.
Hope this is clear to someone
indocti discant et ament meminisse periti