[mutter/gbsneto/graphene-matrix: 19/22] texture-tower: Use graphene APIs

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

commit 79767de3948036919723b8d62c0668884e400969
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Fri Sep 11 19:40:00 2020 -0300

    texture-tower: Use graphene APIs
    
    A boring one, with the exception that row and column needed to be
    swapped. For the sake of consistency, the variable names were also
    synchronized with the values they hold, so e.g. xy → yx, etc.
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1439

 src/compositor/meta-texture-tower.c | 44 ++++++++++++++++++-------------------
 1 file changed, 22 insertions(+), 22 deletions(-)
---
diff --git a/src/compositor/meta-texture-tower.c b/src/compositor/meta-texture-tower.c
index 87c9ff3de4..cb7b997262 100644
--- a/src/compositor/meta-texture-tower.c
+++ b/src/compositor/meta-texture-tower.c
@@ -281,17 +281,17 @@ get_paint_level (ClutterPaintContext *paint_context,
   cogl_framebuffer_get_projection_matrix (framebuffer, &projection);
   cogl_framebuffer_get_modelview_matrix (framebuffer, &modelview);
 
-  cogl_matrix_multiply (&pm, &projection, &modelview);
-
-  xx = cogl_matrix_get_value (&pm, 0, 0);
-  xy = cogl_matrix_get_value (&pm, 0, 1);
-  xw = cogl_matrix_get_value (&pm, 0, 3);
-  yx = cogl_matrix_get_value (&pm, 1, 0);
-  yy = cogl_matrix_get_value (&pm, 1, 1);
-  yw = cogl_matrix_get_value (&pm, 1, 3);
-  wx = cogl_matrix_get_value (&pm, 3, 0);
-  wy = cogl_matrix_get_value (&pm, 3, 1);
-  ww = cogl_matrix_get_value (&pm, 3, 3);
+  graphene_matrix_multiply (&modelview, &projection, &pm);
+
+  xx = graphene_matrix_get_value (&pm, 0, 0);
+  xy = graphene_matrix_get_value (&pm, 0, 1);
+  xw = graphene_matrix_get_value (&pm, 0, 3);
+  yx = graphene_matrix_get_value (&pm, 1, 0);
+  yy = graphene_matrix_get_value (&pm, 1, 1);
+  yw = graphene_matrix_get_value (&pm, 1, 3);
+  wx = graphene_matrix_get_value (&pm, 3, 0);
+  wy = graphene_matrix_get_value (&pm, 3, 1);
+  ww = graphene_matrix_get_value (&pm, 3, 3);
 
   cogl_framebuffer_get_viewport4fv (framebuffer, v);
   viewport_width = v[2];
@@ -300,9 +300,9 @@ get_paint_level (ClutterPaintContext *paint_context,
   u0 = width / 2.;
   v0 = height / 2.;
 
-  xc = xx * u0 + xy * v0 + xw;
-  yc = yx * u0 + yy * v0 + yw;
-  wc = wx * u0 + wy * v0 + ww;
+  xc = xx * u0 + yx * v0 + wx;
+  yc = xy * u0 + yy * v0 + wy;
+  wc = xw * u0 + yw * v0 + ww;
 
   /* We'll simplify the equations below for a bit of micro-optimization.
    * The commented out code is the unsimplified version.
@@ -315,10 +315,10 @@ get_paint_level (ClutterPaintContext *paint_context,
   // with respect to u, v, using
   // d(a/b)/dx = da/dx * (1/b) - a * db/dx / (b^2)
 
-  dxdu = 0.5 * viewport_width * (xx - wx * (xc/wc)) / wc;
-  dxdv = 0.5 * viewport_width * (xy - wy * (xc/wc)) / wc;
-  dydu = 0.5 * viewport_height * (yx - wx * (yc/wc)) / wc;
-  dydv = 0.5 * viewport_height * (yy - wy * (yc/wc)) / wc;
+  dxdu = 0.5 * viewport_width * (xx - xw * (xc/wc)) / wc;
+  dxdv = 0.5 * viewport_width * (yx - yw * (xc/wc)) / wc;
+  dydu = 0.5 * viewport_height * (xy - xw * (yc/wc)) / wc;
+  dydv = 0.5 * viewport_height * (yy - yw * (yc/wc)) / wc;
 
   // Compute the inverse partials as the matrix inverse
   det = dxdu * dydv - dxdv * dydu;
@@ -337,10 +337,10 @@ get_paint_level (ClutterPaintContext *paint_context,
   */
 
   /* dxdu * wc, etc */
-  dxdu_ = 0.5 * viewport_width * (xx - wx * (xc/wc));
-  dxdv_ = 0.5 * viewport_width * (xy - wy * (xc/wc));
-  dydu_ = 0.5 * viewport_height * (yx - wx * (yc/wc));
-  dydv_ = 0.5 * viewport_height * (yy - wy * (yc/wc));
+  dxdu_ = 0.5 * viewport_width * (xx - xw * (xc/wc));
+  dxdv_ = 0.5 * viewport_width * (yx - yw * (xc/wc));
+  dydu_ = 0.5 * viewport_height * (xy - xw * (yc/wc));
+  dydv_ = 0.5 * viewport_height * (yy - yw * (yc/wc));
 
   /* det * wc^2 */
   det_ = dxdu_ * dydv_ - dxdv_ * dydu_;