Align to Normal

THE POST BELOW IS MORE THAN 5 YEARS OLD. RELATED SUPPORT INFORMATION MIGHT BE OUTDATED OR DEPRECATED

On 16/03/2005 at 07:53, xxxxxxxx wrote:

User Information:
Cinema 4D Version:   9.1 
Platform:   Windows  ; Mac  ;  Mac OSX  ; 
Language(s) :     C++  ;

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Hi,

I have a problem. I get the normal of a polygon with CalcFaceNormal(). Then I construct a rotation matrix out of it and set it to an object to align it to that normal.

Works fine so far, but the normal gives me headaches. If I rotate the polygon around 1 axis, the whole normal changes (so all 3 components), which means the constructed matrix has rotations in other axis too, which results in the object to rotate around other axis although the normal has only been rotated around 1 axis.

Anybody knows how to solve this? Any ideas?

Thank you very much!
Katachi

THE POST BELOW IS MORE THAN 5 YEARS OLD. RELATED SUPPORT INFORMATION MIGHT BE OUTDATED OR DEPRECATED

On 17/03/2005 at 11:45, xxxxxxxx wrote:

you need to construct your matrix with an upvector. if you need your object to stick to the surface then you could try using !(padr[vadr[0]]-padr[vadr[2]]) as your upvector, this will ensure (provided the winding doesn't change) that you have a constant relative upvector

then just construct your matrix as follows:

mat.v3=normal;
mat.v2=upvector;
mat.v1=normal%upvector;
(you might wanna do cross products on the other two afterwards just to make sure that the matrix is orthogonal)

THE POST BELOW IS MORE THAN 5 YEARS OLD. RELATED SUPPORT INFORMATION MIGHT BE OUTDATED OR DEPRECATED

On 17/03/2005 at 11:48, xxxxxxxx wrote:

Ah! Good idea with using the points as upvector! (why didn´t I think of this? :)
The matrix construction is clear.

Thanks!