[mutter/gbsneto/graphene-matrix: 13/41] Don't access CoglMatrix struct fields

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

commit e4e298b008bcfc79c23bdcb4af16e124bddaa37f
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Wed Sep 9 22:16:25 2020 -0300

    Don't access CoglMatrix struct fields
    
    Instead, use the new cogl_matrix_get_value() API.
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1439

 clutter/clutter/clutter-stage.c                    |  7 ++--
 src/compositor/meta-texture-tower.c                | 37 +++++++++++++++-------
 .../clutter/interactive/test-cogl-offscreen.c      |  2 +-
 3 files changed, 31 insertions(+), 15 deletions(-)
---
diff --git a/clutter/clutter/clutter-stage.c b/clutter/clutter/clutter-stage.c
index e4c129eada..70eeda3b83 100644
--- a/clutter/clutter/clutter-stage.c
+++ b/clutter/clutter/clutter-stage.c
@@ -673,6 +673,7 @@ _cogl_util_get_eye_planes_for_screen_poly (float *polygon,
   Vector4 *poly;
   graphene_vec3_t b;
   graphene_vec3_t c;
+  float wz, ww;
   int count;
 
   tmp_poly = g_alloca (sizeof (Vector4) * n_vertices * 2);
@@ -693,7 +694,9 @@ _cogl_util_get_eye_planes_for_screen_poly (float *polygon,
    * frustum; coordinates range from [-Wc,Wc] left to right on the
    * x-axis and [Wc,-Wc] top to bottom on the y-axis.
    */
-  Wc = DEPTH * projection->wz + projection->ww;
+  wz = cogl_matrix_get_value (projection, 3, 2);
+  ww = cogl_matrix_get_value (projection, 3, 3);
+  Wc = DEPTH * wz + ww;
 
 #define CLIP_X(X) ((((float)X - viewport[0]) * (2.0 / viewport[2])) - 1) * Wc
 #define CLIP_Y(Y) ((((float)Y - viewport[1]) * (2.0 / viewport[3])) - 1) * -Wc
@@ -706,7 +709,7 @@ _cogl_util_get_eye_planes_for_screen_poly (float *polygon,
       tmp_poly[i].w = Wc;
     }
 
-  Wc = DEPTH * 2 * projection->wz + projection->ww;
+  Wc = DEPTH * 2 * wz + ww;
 
   /* FIXME: technically we don't need to project all of the points
    * twice, it would be enough project every other point since
diff --git a/src/compositor/meta-texture-tower.c b/src/compositor/meta-texture-tower.c
index b0df9ed06a..408c0c2e94 100644
--- a/src/compositor/meta-texture-tower.c
+++ b/src/compositor/meta-texture-tower.c
@@ -249,6 +249,9 @@ get_paint_level (ClutterPaintContext *paint_context,
 {
   CoglFramebuffer *framebuffer;
   CoglMatrix projection, modelview, pm;
+  float xx, xy, xw;
+  float yx, yy, yw;
+  float wx, wy, ww;
   float v[4];
   double viewport_width, viewport_height;
   double u0, v0;
@@ -280,6 +283,16 @@ get_paint_level (ClutterPaintContext *paint_context,
 
   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);
+
   cogl_framebuffer_get_viewport4fv (framebuffer, v);
   viewport_width = v[2];
   viewport_height = v[3];
@@ -287,9 +300,9 @@ get_paint_level (ClutterPaintContext *paint_context,
   u0 = width / 2.;
   v0 = height / 2.;
 
-  xc = pm.xx * u0 + pm.xy * v0 + pm.xw;
-  yc = pm.yx * u0 + pm.yy * v0 + pm.yw;
-  wc = pm.wx * u0 + pm.wy * v0 + pm.ww;
+  xc = xx * u0 + xy * v0 + xw;
+  yc = yx * u0 + yy * v0 + yw;
+  wc = wx * u0 + wy * v0 + ww;
 
   /* We'll simplify the equations below for a bit of micro-optimization.
    * The commented out code is the unsimplified version.
@@ -302,10 +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 * (pm.xx - pm.wx * (xc/wc)) / wc;
-  dxdv = 0.5 * viewport_width * (pm.xy - pm.wy * (xc/wc)) / wc;
-  dydu = 0.5 * viewport_height * (pm.yx - pm.wx * (yc/wc)) / wc;
-  dydv = 0.5 * viewport_height * (pm.yy - pm.wy * (yc/wc)) / wc;
+  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;
 
   // Compute the inverse partials as the matrix inverse
   det = dxdu * dydv - dxdv * dydu;
@@ -324,10 +337,10 @@ get_paint_level (ClutterPaintContext *paint_context,
   */
 
   /* dxdu * wc, etc */
-  dxdu_ = 0.5 * viewport_width * (pm.xx - pm.wx * (xc/wc));
-  dxdv_ = 0.5 * viewport_width * (pm.xy - pm.wy * (xc/wc));
-  dydu_ = 0.5 * viewport_height * (pm.yx - pm.wx * (yc/wc));
-  dydv_ = 0.5 * viewport_height * (pm.yy - pm.wy * (yc/wc));
+  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));
 
   /* det * wc^2 */
   det_ = dxdu_ * dydv_ - dxdv_ * dydu_;
@@ -340,7 +353,7 @@ get_paint_level (ClutterPaintContext *paint_context,
   lambda = 0.5 * M_LOG2E * log (rho_sq * wc * wc / det_sq) + LOD_BIAS;
 
 #if 0
-  g_print ("%g %g %g\n", 0.5 * viewport_width * pm.xx / pm.ww, 0.5 * viewport_height * pm.yy / pm.ww, 
lambda);
+  g_print ("%g %g %g\n", 0.5 * viewport_width * xx / ww, 0.5 * viewport_height * yy / ww, lambda);
 #endif
 
   if (lambda <= 0.)
diff --git a/src/tests/clutter/interactive/test-cogl-offscreen.c 
b/src/tests/clutter/interactive/test-cogl-offscreen.c
index 8580fb45a4..d8c3f92997 100644
--- a/src/tests/clutter/interactive/test-cogl-offscreen.c
+++ b/src/tests/clutter/interactive/test-cogl-offscreen.c
@@ -232,7 +232,7 @@ setup_viewport (CoglFramebuffer *framebuffer,
    */
 
   cogl_framebuffer_get_projection_matrix (framebuffer, &projection_matrix);
-  z_camera = 0.5 * projection_matrix.xx;
+  z_camera = 0.5 * cogl_matrix_get_value (&projection_matrix, 0, 0);
 
   cogl_matrix_init_identity (&mv_matrix);
   cogl_matrix_translate (&mv_matrix, -0.5f, -0.5f, -z_camera);