Re: [Plib-devel] Releasing PLIB 1.2 *soon*.

[<Va...@t-...>]

Steve Baker wrote:
> 
> A not-normalized normal is a vector and a normalized vector is
> a normal - so I find the names a bit confusing.

A normal is a vector that decribes the 'direction' of a plane. So if
  you have got a 4th number you could write the plane equation 
  (A x1 + B x2 + C x3 + D = 0 with A, B and C defining the normal)

A normalized vector is a unit vector (i.e. legth == 1.0).

This was that I thought of. But you are right it's confusing, it
should be e.g. sgProjectOnUnitVector3

> I'm not quite sure what you intend these to do

With this misunderstanding it's obvious that you don't know it...

> but how about
> 
> sgProjectVec3OntoPlane

this would be the sgProjectOnNormal3 as the normal is defining the plane

> sgProjectNormal3OntoPlane

this wouldn't make sense as the resuld would be a zero vector...

Yesterdy I've sent you the code (+ a patch a short time after I've sent
the code) privately. It comes with descriptions of the functions. But
please change the names to something less confusing (and update the
CVS as I don't have SSH). For the interested here are the descriptions:

// sgProjectOn[Normalized]VecX ( sgVecX dst, const sgVecX src1, const
sgVecX src2 )
// 
// calculate the projection of src2 onto src1:
//         _ 
//         /|
//  src2 /  :
//     /    :
//   /      :
//  -------->-------------->
//     dst      src1
//
//        src1 o src2
//  dst = ----------- * src1
//        ( src1 )^2


// sgProjectOnNormal3 ( sgVec3 dst, const sgVec3 src1, const sgVec3 src2
)
//
// calculate the projection of src2 onto a plane that is specified by
src1,
// its normal vector
//
// This works by calculating temp, a vector that lies on the plane and
has the
// direction of the projected vector and then do the same stuff as above
//
//                                      temp o src2
// temp = ( src1 x src2 ) x src1; dst = ----------- * temp
//                                      ( temp )^2

CU,
Christian