shz_mat4x4_inverse_block_triangular

void shz_mat4x4_inverse_block_triangular(const shz_mat4x4_t* mtx, shz_mat4x4_t* out) SHZ_NOEXCEPT;

Computes the inverse of a 4x4 matrix in block-triangular form.

Parameters

Name	Type	Description
mtx	const shz_mat4x4_t *
out	shz_mat4x4_t *

Returns

Nothing (void).

Details

This is a special-case faster optimization for 4x4 matrices which take the form:

A = [ M   b ]
    [ 0   w ]

Where A is 4x4, M is 3x3, b is 3x1, and the bottom row is (0, 0, 0, w) with w != 0. For this block-triangular form, det(A) = det(M) * w. Then

inv(A) = [ inv(M)        -inv(M) * b / w ]
         [   0                 1/w       ]

Notes

• A regular 3D transform matrix is already in this form.
• shz_mat4x4_inverse() will dynamically check whether to use this optimization.

Naming and requirements

• shz_mat4x4_t and shz_mat2x2_t arguments must be 8-byte aligned. Unaligned data goes through the float[16] parameters of the _unaligned routines.

Availability

• C++ equivalent: shz::mat4x4::inverse_block_triangular
• Type-generic form: none
• Back-ends: SH4: shared C implementation · SW: portable C · SPU: shared C implementation
• Defined in: sh4zam/shz_matrix.h:844
• Module: Matrix, section "Miscellaneous"