In order to apply the zoom transformation to the output matrix, Weston was
doing the following:
• Create a temporary matrix to hold the translation
• Invert the translation matrix using weston_matrix_invert into
another temporary matrix
• Scale that matrix by the scale factor
• Multiply the current matrix with the temporary matrix
Using weston_matrix_invert to invert a translation matrix is over the top.
Instead we can just negate the values we pass to weston_matrix_translate.
Matrix multiplication is associative so creating a temporary matrix to hold the
scale and translation transform should be equivalent to just applying them
directly to the output matrix.
---
src/compositor.c | 13 ++++---------
1 file changed, 4 insertions(+), 9 deletions(-)
diff --git a/src/compositor.c b/src/compositor.c
index fd2decb..f836cf7 100644
--- a/src/compositor.c
+++ b/src/compositor.c
@@ -3186,8 +3186,6 @@ WL_EXPORT void
weston_output_update_matrix(struct weston_output *output)
{
float magnification;
- struct weston_matrix camera;
- struct weston_matrix modelview;
weston_matrix_init(&output->matrix);
weston_matrix_translate(&output->matrix,
@@ -3202,14 +3200,11 @@ weston_output_update_matrix(struct weston_output
*output)
if (output->zoom.active) {
magnification = 1 / (1 - output->zoom.spring_z.current);
- weston_matrix_init(&camera);
- weston_matrix_init(&modelview);
weston_output_update_zoom(output);
- weston_matrix_translate(&camera, output->zoom.trans_x,
- -output->zoom.trans_y, 0);
- weston_matrix_invert(&modelview, &camera);
- weston_matrix_scale(&modelview, magnification, magnification,
1.0);
- weston_matrix_multiply(&output->matrix, &modelview);
+ weston_matrix_translate(&output->matrix, -output->zoom.trans_x,
+ output->zoom.trans_y, 0);
+ weston_matrix_scale(&output->matrix, magnification,
+ magnification, 1.0);
}
output->dirty = 0;
--
1.9.0
_______________________________________________
wayland-devel mailing list
wayland-devel@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/wayland-devel
