matrix: Introduce weston_coord

All through weston we have code that passes int x, y or
float x, y or wl_fixed_t x, y pairs. These pairs are frequently
converted to/from wl_fixed_t and other types.

We also have struct vec2d and struct weston_geometry which also
contain coordinate pairs.

Let's create a family of coordinate vector structures for coordinate
pairs and use it anywhere we sensibly can.

This has a few benefits - it helps remove intermediate conversion
between fixed/float/int types. It lets us roll the homogenous
coordinate normalization bits into helper functions instead of
needing them open coded throughout the source.

Possibly most importantly, it also allows us to do some compile time
validation of what coordinate space we're working in.

Signed-off-by: Derek Foreman <derek.foreman@collabora.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/shared/matrix.c b/shared/matrix.c
index f41abe76..472f299a 100644
--- a/shared/matrix.c
+++ b/shared/matrix.c
@@ -126,6 +126,22 @@ weston_matrix_transform(const struct weston_matrix *matrix,
 	*v = t;
 }
 
+WL_EXPORT struct weston_coord
+weston_matrix_transform_coord(const struct weston_matrix *matrix,
+			      struct weston_coord c)
+{
+	struct weston_coord out;
+	struct weston_vector t = { { c.x, c.y, 0.0, 1.0 } };
+
+	weston_matrix_transform(matrix, &t);
+
+	assert(fabsf(t.f[3]) > 1e-6);
+
+	out.x = t.f[0] / t.f[3];
+	out.y = t.f[1] / t.f[3];
+	return out;
+}
+
 static inline void
 swap_rows(double *a, double *b)
 {