compositor: drop inverse matrix from weston_transform

Remove the inverse matrix member from struct weston_transform. It is
easier (and probably faster, too) to create and store only forward
transformation matrices in a list, multiply them once, and then invert
the final matrix, rather than creating both forward and inverse
matrices, and multiplying both.

Add a stub for the 4x4 matrix inversion function.

Signed-off-by: Pekka Paalanen <ppaalanen@gmail.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/src/matrix.c b/src/matrix.c
index c71471f1..941e9584 100644
--- a/src/matrix.c
+++ b/src/matrix.c
@@ -100,3 +100,10 @@ weston_matrix_transform(struct weston_matrix *matrix, struct weston_vector *v)
 
 	*v = t;
 }
+
+WL_EXPORT int
+weston_matrix_invert(struct weston_matrix *inverse,
+		     const struct weston_matrix *matrix)
+{
+	return -1; /* fail */
+}