[mutter/gbsneto/graphene-frustrum: 4/19] clutter: Use graphene_matrix_inverse()

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

commit 335610bb1a3ccb05b021f9d264fc1e51d3411659
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Sun Oct 11 13:30:25 2020 -0300

    clutter: Use graphene_matrix_inverse()
    
    Instead of our own implementation that upscales, then downscales back,
    use graphene_matrix_inverse() directly. This is possible after switching
    to a z-near value that doesn't have problems with float precision.
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1489

 clutter/clutter/clutter-actor.c |  5 ++---
 clutter/clutter/clutter-stage.c |  4 ++--
 cogl/cogl/cogl-graphene.c       | 35 -----------------------------------
 cogl/cogl/cogl-graphene.h       | 16 ----------------
 cogl/cogl/cogl-matrix-stack.c   |  4 ++--
 5 files changed, 6 insertions(+), 58 deletions(-)
---
diff --git a/clutter/clutter/clutter-actor.c b/clutter/clutter/clutter-actor.c
index 2e19e24f72..9034545231 100644
--- a/clutter/clutter/clutter-actor.c
+++ b/clutter/clutter/clutter-actor.c
@@ -3165,9 +3165,8 @@ ensure_valid_actor_transform (ClutterActor *actor)
   graphene_matrix_init_identity (&priv->transform);
 
   CLUTTER_ACTOR_GET_CLASS (actor)->apply_transform (actor, &priv->transform);
-  priv->has_inverse_transform =
-    cogl_graphene_matrix_get_inverse (&priv->transform,
-                                      &priv->inverse_transform);
+  priv->has_inverse_transform = graphene_matrix_inverse (&priv->transform,
+                                                         &priv->inverse_transform);
 
   priv->transform_valid = TRUE;
 }
diff --git a/clutter/clutter/clutter-stage.c b/clutter/clutter/clutter-stage.c
index 2f362f29c5..ac6f500a31 100644
--- a/clutter/clutter/clutter-stage.c
+++ b/clutter/clutter/clutter-stage.c
@@ -2068,8 +2068,8 @@ clutter_stage_set_perspective (ClutterStage       *stage,
                                     priv->perspective.aspect,
                                     priv->perspective.z_near,
                                     priv->perspective.z_far);
-  cogl_graphene_matrix_get_inverse (&priv->projection,
-                                    &priv->inverse_projection);
+  graphene_matrix_inverse (&priv->projection,
+                           &priv->inverse_projection);
 
   _clutter_stage_dirty_projection (stage);
   clutter_actor_queue_redraw (CLUTTER_ACTOR (stage));
diff --git a/cogl/cogl/cogl-graphene.c b/cogl/cogl/cogl-graphene.c
index 90e1f5b86b..d9bd3bd42c 100644
--- a/cogl/cogl/cogl-graphene.c
+++ b/cogl/cogl/cogl-graphene.c
@@ -274,38 +274,3 @@ cogl_graphene_matrix_project_points (const graphene_matrix_t *matrix,
                          n_points);
     }
 }
-
-gboolean
-cogl_graphene_matrix_get_inverse (const graphene_matrix_t *matrix,
-                                  graphene_matrix_t       *inverse)
-{
-  graphene_matrix_t scaled;
-  graphene_matrix_t m;
-  gboolean invertible;
-  float pivot = G_MAXFLOAT;
-  float v[16];
-  float scale;
-
-  graphene_matrix_init_from_matrix (&m, matrix);
-  graphene_matrix_to_float (&m, v);
-
-  pivot = MIN (pivot, v[0]);
-  pivot = MIN (pivot, v[5]);
-  pivot = MIN (pivot, v[10]);
-  pivot = MIN (pivot, v[15]);
-  scale = 1.f / pivot;
-
-  graphene_matrix_init_scale (&scaled, scale, scale, scale);
-
-  /* Float precision is a limiting factor */
-  graphene_matrix_multiply (&m, &scaled, &m);
-
-  invertible = graphene_matrix_inverse (&m, inverse);
-
-  if (invertible)
-    graphene_matrix_multiply (&scaled, inverse, inverse);
-  else
-    graphene_matrix_init_identity (inverse);
-
-  return invertible;
-}
diff --git a/cogl/cogl/cogl-graphene.h b/cogl/cogl/cogl-graphene.h
index 4a561f6d84..4206297108 100644
--- a/cogl/cogl/cogl-graphene.h
+++ b/cogl/cogl/cogl-graphene.h
@@ -163,22 +163,6 @@ cogl_graphene_matrix_project_points (const graphene_matrix_t *matrix,
                                      void                    *points_out,
                                      int                      n_points);
 
-/**
- * cogl_graphene_matrix_get_inverse:
- * @matrix: A 4x4 transformation matrix
- * @inverse: (out): The destination for a 4x4 inverse transformation matrix
- *
- * Gets the inverse transform of a given matrix and uses it to initialize
- * a new #graphene_matrix_t.
- *
- * Return value: %TRUE if the inverse was successfully calculated or %FALSE
- *   for degenerate transformations that can't be inverted (in this case the
- *   @inverse matrix will simply be initialized with the identity matrix)
- */
-COGL_EXPORT gboolean
-cogl_graphene_matrix_get_inverse (const graphene_matrix_t *matrix,
-                                  graphene_matrix_t       *inverse);
-
 G_END_DECLS
 
 #endif /* COGL_GRAPHENE_H */
diff --git a/cogl/cogl/cogl-matrix-stack.c b/cogl/cogl/cogl-matrix-stack.c
index 3f68830681..4e132baf5c 100644
--- a/cogl/cogl/cogl-matrix-stack.c
+++ b/cogl/cogl/cogl-matrix-stack.c
@@ -358,9 +358,9 @@ cogl_matrix_stack_get_inverse (CoglMatrixStack   *stack,
   graphene_matrix_t *internal = cogl_matrix_stack_get (stack, &matrix);
 
   if (internal)
-    return cogl_graphene_matrix_get_inverse (internal, inverse);
+    return graphene_matrix_inverse (internal, inverse);
   else
-    return cogl_graphene_matrix_get_inverse (&matrix, inverse);
+    return graphene_matrix_inverse (&matrix, inverse);
 }
 
 /* In addition to writing the stack matrix into the give @matrix