GenRotateMatrix
Section: C Library Functions (3)
Updated: IRIT Version 6.0
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NAME
GenRotateMatrix()
SYNOPSIS
geom_lib/convex.c:102
void GenRotateMatrix(MatrixType Mat, VectorType Dir)
DESCRIPTION
Routine to prepare a transformation martix to rotate such that Dir is
parallel to the Z axes. Used by the convex decomposition to rotate the
polygons to be XY plane parallel.
Algorithm: form a 4 by 4 matrix from Dir as follows:
| Tx Ty Tz 0 | A transformation which takes the coord
| Bx By Bz 0 | system into T, N & B as required.
[X Y Z 1] * | Nx Ny Nz 0 |
| 0 0 0 1 |
N is exactly Dir, but we got freedom on T & B which must be on
a plane perpendicular to N and perpendicular between them but thats all!
T is therefore selected using this (heuristic ?) algorithm:
Let P be the axis of which the absolute N coefficient is the smallest.
Let B be (N cross P) and T be (B cross N).
PARAMETERS:
Mat: To place the constructed homogeneous transformation.
Dir: To derive a transformation such that Dir goes to Z axis.
FUNCTION RETURN VALUE
void
ORIGIN
(C) Copyright 1989/90-95 Gershon Elber, Technion, IIT
Index
- NAME
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- SYNOPSIS
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- DESCRIPTION
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- PARAMETERS:
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- FUNCTION RETURN VALUE
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- ORIGIN
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