[mutter/gbsneto/graphene-matrix: 1/57] cogl/matrix: Multiply using graphene matrices

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 19da440e7cedead0eb01a10792c92a18937ea54e
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Thu Sep 10 10:34:15 2020 -0300

    cogl/matrix: Multiply using graphene matrices
    
    At this point, we are still only changing CoglMatrix APIs internally,
    and it should still produce the same output as before. To achieve this,
    exploit the fact that graphene matrices are row-major with row vectors,
    which allows us to multiply as B x A (the reverse order) instead of
    A x B, and that results in the same matrix that Cogl would generate.
    
    By doing this, no consumer of this API needs to be changed for now.
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1439

 cogl/cogl/cogl-matrix.c | 32 +++++++++++---------------------
 1 file changed, 11 insertions(+), 21 deletions(-)
---
diff --git a/cogl/cogl/cogl-matrix.c b/cogl/cogl/cogl-matrix.c
index 4f65b16cf9..d191bed9e9 100644
--- a/cogl/cogl/cogl-matrix.c
+++ b/cogl/cogl/cogl-matrix.c
@@ -326,32 +326,22 @@ matrix_multiply_array_with_flags (CoglMatrix *result,
     matrix_multiply4x4 ((float *)result, (float *)result, array);
 }
 
-/* Joins both flags and marks the type and inverse as dirty.  Calls
- * matrix_multiply3x4() if both matrices are 3D, or matrix_multiply4x4()
- * otherwise.
- */
-static void
-_cogl_matrix_multiply (CoglMatrix *result,
-                       const CoglMatrix *a,
-                       const CoglMatrix *b)
-{
-  result->flags = (a->flags |
-                   b->flags |
-                   MAT_DIRTY_TYPE |
-                   MAT_DIRTY_INVERSE);
-
-  if (TEST_MAT_FLAGS(result, MAT_FLAGS_3D))
-    matrix_multiply3x4 ((float *)result, (float *)a, (float *)b);
-  else
-    matrix_multiply4x4 ((float *)result, (float *)a, (float *)b);
-}
-
 void
 cogl_matrix_multiply (CoglMatrix *result,
                      const CoglMatrix *a,
                      const CoglMatrix *b)
 {
-  _cogl_matrix_multiply (result, a, b);
+  graphene_matrix_t res;
+  graphene_matrix_t ma;
+  graphene_matrix_t mb;
+
+  cogl_matrix_to_graphene_matrix (a, &ma);
+  cogl_matrix_to_graphene_matrix (b, &mb);
+  graphene_matrix_multiply (&mb, &ma, &res);
+  graphene_matrix_to_cogl_matrix (&res, result);
+
+  result->flags = a->flags | b->flags | MAT_DIRTY_TYPE | MAT_DIRTY_INVERSE;
+
   _COGL_MATRIX_DEBUG_PRINT (result);
 }