:DECOMPOSE

source files: [xc]tfm.[ch]

SYNTAX

(SEND <tfm> :DECOMPOSE)

DESCRIPTION

Decompose a non-degenerate 4x4 transformation matrix <tfm> into the sequence of transformations that produced it. If the matrix can be decomposed, the call will return a property list with the following attributes:

:SCALE (x y z)

Scaling factors relative to the X, Y, and Z axes.

:SHEAR (x/y x/z y/z)

Three shear factors: X relative to Y, X relative to Z, and Y relative to Z. These correspond to the first, second, and fourth coefficients of the :SHEAR method.

:ROTATE (x y z)

Angles of rotation about the X, Y, and Z axes respectively, specified in radians.

:MOVE (x y z)

Translation in X, Y, and Z directions.

:PERSPECTIVE (x y z w)

Four perspective coefficients. (Skandha doesn't currently have a way to add perspective to a transform matrix directly, so these four values will probably be zero all the time.)

If the matrix is singular and can't be decomposed, this call will return NIL.

Note that the order in which these separate transformations are applied matters. To reconstruct the original matrix <tfm>, the components should be applied in the following order:

[Sx][Sy][Sz][Shearx/y][Sx/z][Sz/y][Rx][Ry][Rz][Tx][Ty][Tz][P(x,y,z,w)]