[mutter/gbsneto/graphene2: 19/45] cogl/matrix: Change semantincs of cogl_matrix_get_array

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

commit 54f9bebeb8a0cf20b076d9d019bf57768247f597
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Fri Feb 22 15:06:34 2019 -0300

    cogl/matrix: Change semantincs of cogl_matrix_get_array
    
    CoglMatrix.get_array() returns the column-major CoglMatrix itself,
    since the first fields of the matrix is effectively an array of
    floats, and we can just pretend it is. Of course, it basically
    ignores any C-specific type checking.
    
    WIP

 cogl/cogl/cogl-matrix.c                          | 11 +++++---
 cogl/cogl/cogl-matrix.h                          |  8 +++---
 cogl/cogl/driver/gl/cogl-clip-stack-gl.c         | 10 +++++--
 cogl/cogl/driver/gl/cogl-pipeline-progend-glsl.c | 34 +++++++++++++++---------
 cogl/tests/conform/test-pipeline-uniforms.c      |  4 +--
 cogl/tests/conform/test-snippets.c               |  4 ++-
 6 files changed, 45 insertions(+), 26 deletions(-)
---
diff --git a/cogl/cogl/cogl-matrix.c b/cogl/cogl/cogl-matrix.c
index 99b2eb056..d658c2560 100644
--- a/cogl/cogl/cogl-matrix.c
+++ b/cogl/cogl/cogl-matrix.c
@@ -1996,10 +1996,11 @@ cogl_matrix_free (CoglMatrix *matrix)
   g_slice_free (CoglMatrix, matrix);
 }
 
-const float *
-cogl_matrix_get_array (const CoglMatrix *matrix)
+void
+cogl_matrix_get_array (const CoglMatrix *matrix,
+                       float *array)
 {
-  return (float *)matrix;
+  memcpy (array, matrix, sizeof (float) * 16);
 }
 
 void
@@ -2291,13 +2292,15 @@ void
 cogl_matrix_transpose (CoglMatrix *matrix)
 {
   float new_values[16];
+  float values[16];
 
   /* We don't need to do anything if the matrix is the identity matrix */
   if (!(matrix->flags & MAT_DIRTY_TYPE) &&
       matrix->type == COGL_MATRIX_TYPE_IDENTITY)
     return;
 
-  _cogl_matrix_util_transposef (new_values, cogl_matrix_get_array (matrix));
+  cogl_matrix_get_array (matrix, values);
+  _cogl_matrix_util_transposef (new_values, values);
 
   cogl_matrix_init_from_array (matrix, new_values);
 }
diff --git a/cogl/cogl/cogl-matrix.h b/cogl/cogl/cogl-matrix.h
index 1eb897443..bf6e97c53 100644
--- a/cogl/cogl/cogl-matrix.h
+++ b/cogl/cogl/cogl-matrix.h
@@ -508,13 +508,13 @@ cogl_matrix_init_from_array (CoglMatrix *matrix,
 /**
  * cogl_matrix_get_array:
  * @matrix: A 4x4 transformation matrix
+ * @array: the array to copy the contents of @matrix to.
  *
  * Casts @matrix to a float array which can be directly passed to OpenGL.
- *
- * Return value: a pointer to the float array
  */
-const float *
-cogl_matrix_get_array (const CoglMatrix *matrix);
+void
+cogl_matrix_get_array (const CoglMatrix *matrix,
+                       float *array);
 
 /**
  * cogl_matrix_init_from_quaternion:
diff --git a/cogl/cogl/driver/gl/cogl-clip-stack-gl.c b/cogl/cogl/driver/gl/cogl-clip-stack-gl.c
index 9a3a2cee2..1954808ed 100644
--- a/cogl/cogl/driver/gl/cogl-clip-stack-gl.c
+++ b/cogl/cogl/driver/gl/cogl-clip-stack-gl.c
@@ -84,9 +84,15 @@ flush_matrix_to_gl_builtin (CoglContext    *ctx,
     }
 
   if (is_identity)
-    GE (ctx, glLoadIdentity ());
+    {
+      GE (ctx, glLoadIdentity ());
+    }
   else
-    GE (ctx, glLoadMatrixf (cogl_matrix_get_array (matrix)));
+    {
+      float array[16];
+      cogl_matrix_get_array (matrix, array);
+      GE (ctx, glLoadMatrixf (array));
+    }
 #endif
 }
 
diff --git a/cogl/cogl/driver/gl/cogl-pipeline-progend-glsl.c 
b/cogl/cogl/driver/gl/cogl-pipeline-progend-glsl.c
index 1f9baa9be..819825232 100644
--- a/cogl/cogl/driver/gl/cogl-pipeline-progend-glsl.c
+++ b/cogl/cogl/driver/gl/cogl-pipeline-progend-glsl.c
@@ -440,10 +440,10 @@ update_constants_cb (CoglPipeline *pipeline,
       (state->update_all || unit_state->dirty_texture_matrix))
     {
       const CoglMatrix *matrix;
-      const float *array;
+      float array[16];
 
       matrix = _cogl_pipeline_get_layer_matrix (pipeline, layer_index);
-      array = cogl_matrix_get_array (matrix);
+      cogl_matrix_get_array (matrix, array);
       GE (ctx, glUniformMatrix4fv (unit_state->texture_matrix_uniform,
                                    1, FALSE, array));
       unit_state->dirty_texture_matrix = FALSE;
@@ -965,6 +965,8 @@ _cogl_pipeline_progend_glsl_pre_paint (CoglPipeline *pipeline,
 
   if (modelview_changed || projection_changed)
     {
+      float array[16];
+
       if (program_state->mvp_uniform != -1)
         need_modelview = need_projection = TRUE;
       else
@@ -992,16 +994,22 @@ _cogl_pipeline_progend_glsl_pre_paint (CoglPipeline *pipeline,
         }
 
       if (projection_changed && program_state->projection_uniform != -1)
-        GE (ctx, glUniformMatrix4fv (program_state->projection_uniform,
-                                     1, /* count */
-                                     FALSE, /* transpose */
-                                     cogl_matrix_get_array (&projection)));
+        {
+          cogl_matrix_get_array (&projection, array);
+          GE (ctx, glUniformMatrix4fv (program_state->projection_uniform,
+                                       1, /* count */
+                                       FALSE, /* transpose */
+                                       array));
+        }
 
       if (modelview_changed && program_state->modelview_uniform != -1)
-        GE (ctx, glUniformMatrix4fv (program_state->modelview_uniform,
-                                     1, /* count */
-                                     FALSE, /* transpose */
-                                     cogl_matrix_get_array (&modelview)));
+        {
+          cogl_matrix_get_array (&modelview, array);
+          GE (ctx, glUniformMatrix4fv (program_state->modelview_uniform,
+                                       1, /* count */
+                                       FALSE, /* transpose */
+                                       array));
+        }
 
       if (program_state->mvp_uniform != -1)
         {
@@ -1010,11 +1018,12 @@ _cogl_pipeline_progend_glsl_pre_paint (CoglPipeline *pipeline,
              avoiding the matrix multiplication */
           if (cogl_matrix_entry_is_identity (modelview_entry))
             {
+              cogl_matrix_get_array (&projection, array);
               GE (ctx,
                   glUniformMatrix4fv (program_state->mvp_uniform,
                                       1, /* count */
                                       FALSE, /* transpose */
-                                      cogl_matrix_get_array (&projection)));
+                                      array));
             }
           else
             {
@@ -1023,11 +1032,12 @@ _cogl_pipeline_progend_glsl_pre_paint (CoglPipeline *pipeline,
               cogl_matrix_multiply (&combined,
                                     &projection,
                                     &modelview);
+              cogl_matrix_get_array (&combined, array);
               GE (ctx,
                   glUniformMatrix4fv (program_state->mvp_uniform,
                                       1, /* count */
                                       FALSE, /* transpose */
-                                      cogl_matrix_get_array (&combined)));
+                                      array));
             }
         }
     }
diff --git a/cogl/tests/conform/test-pipeline-uniforms.c b/cogl/tests/conform/test-pipeline-uniforms.c
index ab447b1e5..e04bc8240 100644
--- a/cogl/tests/conform/test-pipeline-uniforms.c
+++ b/cogl/tests/conform/test-pipeline-uniforms.c
@@ -242,9 +242,7 @@ paint_matrix_pipeline (CoglPipeline *pipeline)
   cogl_matrix_transpose (matrices + 3);
 
   for (i = 0; i < 4; i++)
-    memcpy (matrix_floats + i * 16,
-            cogl_matrix_get_array (matrices + i),
-            sizeof (float) * 16);
+    cogl_matrix_get_array (matrices + i, matrix_floats + i * 16);
 
   /* Set the first three matrices as transposed */
   uniform_location =
diff --git a/cogl/tests/conform/test-snippets.c b/cogl/tests/conform/test-snippets.c
index 9b19b221b..944fe953d 100644
--- a/cogl/tests/conform/test-snippets.c
+++ b/cogl/tests/conform/test-snippets.c
@@ -492,6 +492,7 @@ test_vertex_transform_hook (TestState *state)
   CoglSnippet *snippet;
   CoglMatrix identity_matrix;
   CoglMatrix matrix;
+  float array[16];
   int location;
 
   /* Test the vertex transform hook */
@@ -513,12 +514,13 @@ test_vertex_transform_hook (TestState *state)
   /* Copy the current projection matrix to a uniform */
   cogl_framebuffer_get_projection_matrix (test_fb, &matrix);
   location = cogl_pipeline_get_uniform_location (pipeline, "pmat");
+  cogl_matrix_get_array (&matrix, array);
   cogl_pipeline_set_uniform_matrix (pipeline,
                                     location,
                                     4, /* dimensions */
                                     1, /* count */
                                     FALSE, /* don't transpose */
-                                    cogl_matrix_get_array (&matrix));
+                                    array);
 
   /* Replace the real projection matrix with the identity. This should
      mess up the drawing unless the snippet replacement is working */