[Cogl] [PATCH 1/3] texture-2d-slice: Fix the foreach_sub_texture_in_region implementation

[Neil Roberts]

There were a few problems with the sub texture iterating code of
sliced textures which were causing some conformance tests to fail when
NPOT textures are disabled:

• The spans are stored in un-normalized coordinates and the
  coordinates passed to the foreach function are normalized. The
  function was trying to un-normalize them before passing them to the
  span iterator code but it was using the wrong factor which was
  causing it to actually doubley normalize them.

• The shim function to renormalize the coordinates before passing them
  to the callback was renormalizing the sub-texture coordinates
  instead of the virtual coordinates. The sub-texture coordinates are
  already in the right scale for whatever is the underlying texture so
  we don't need to touch them. Instead we need to normalize the
  virtual coordinates because these are coming from the un-normalized
  coordinates that we passed to the span iterating code.

• The normalize factors passed to the span iterating were always 1.
  The code uses this normalizing factor to round the incoming
  coordinates to the nearest multiple of a full texture. It divides
  the coordinates by the factor rather than multiplying so it looks
  like we should be passing the virtual texture size here.
---
 cogl/cogl-texture-2d-sliced.c     | 28 +++++++++++++++++-----------
 tests/conform/test-conform-main.c |  4 ++--
 2 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/cogl/cogl-texture-2d-sliced.c b/cogl/cogl-texture-2d-sliced.c
index 6d1f530..96df692 100644
--- a/cogl/cogl-texture-2d-sliced.c
+++ b/cogl/cogl-texture-2d-sliced.c
@@ -75,15 +75,18 @@ re_normalize_sub_texture_coords_cb (CoglTexture *sub_texture,
                                     void *user_data)
 {
   ForeachData *data = user_data;
+  /* The coordinates passed to the span iterating code were
+   * un-normalized so we need to renormalize them before passing them
+   * on */
   float re_normalized_coords[4] =
     {
-      sub_texture_coords[0] * data->x_normalize_factor,
-      sub_texture_coords[1] * data->y_normalize_factor,
-      sub_texture_coords[2] * data->x_normalize_factor,
-      sub_texture_coords[3] * data->y_normalize_factor
+      meta_coords[0] * data->x_normalize_factor,
+      meta_coords[1] * data->y_normalize_factor,
+      meta_coords[2] * data->x_normalize_factor,
+      meta_coords[3] * data->y_normalize_factor
     };
 
-  data->callback (sub_texture, re_normalized_coords, meta_coords,
+  data->callback (sub_texture, sub_texture_coords, re_normalized_coords,
                   data->user_data);
 }
 
@@ -115,19 +118,22 @@ _cogl_texture_2d_sliced_foreach_sub_texture_in_region (
   data.x_normalize_factor = 1.0f / tex_2ds->width;
   data.y_normalize_factor = 1.0f / tex_2ds->height;
 
-  un_normalized_coords[0] = virtual_tx_1 * data.x_normalize_factor;
-  un_normalized_coords[1] = virtual_ty_1 * data.y_normalize_factor;
-  un_normalized_coords[2] = virtual_tx_2 * data.x_normalize_factor;
-  un_normalized_coords[3] = virtual_ty_2 * data.y_normalize_factor;
+  un_normalized_coords[0] = virtual_tx_1 * tex_2ds->width;
+  un_normalized_coords[1] = virtual_ty_1 * tex_2ds->height;
+  un_normalized_coords[2] = virtual_tx_2 * tex_2ds->width;
+  un_normalized_coords[3] = virtual_ty_2 * tex_2ds->height;
 
+  /* Note that the normalize factors passed here are the reciprocal of
+   * the factors calculated above because the span iterating code
+   * normalizes by dividing by the factor instead of multiplying */
   _cogl_texture_spans_foreach_in_region (x_spans,
                                          tex_2ds->slice_x_spans->len,
                                          y_spans,
                                          tex_2ds->slice_y_spans->len,
                                          textures,
                                          un_normalized_coords,
-                                         1, /* x_normalize_factor */
-                                         1, /* y_normalize_factor */
+                                         tex_2ds->width,
+                                         tex_2ds->height,
                                          COGL_PIPELINE_WRAP_MODE_REPEAT,
                                          COGL_PIPELINE_WRAP_MODE_REPEAT,
                                          re_normalize_sub_texture_coords_cb,
diff --git a/tests/conform/test-conform-main.c b/tests/conform/test-conform-main.c
index c49ea58..5acf2e5 100644
--- a/tests/conform/test-conform-main.c
+++ b/tests/conform/test-conform-main.c
@@ -63,7 +63,7 @@ main (int argc, char **argv)
 
   ADD_TEST (test_sparse_pipeline, 0, 0);
 
-  ADD_TEST (test_npot_texture, 0, TEST_REQUIREMENT_NPOT);
+  ADD_TEST (test_npot_texture, 0, 0);
   UNPORTED_TEST (test_multitexture);
   UNPORTED_TEST (test_texture_mipmaps);
   ADD_TEST (test_sub_texture, 0, 0);
@@ -74,7 +74,7 @@ main (int argc, char **argv)
   ADD_TEST (test_texture_3d, TEST_REQUIREMENT_TEXTURE_3D, 0);
   ADD_TEST (test_wrap_modes, 0, 0);
   UNPORTED_TEST (test_texture_pixmap_x11);
-  ADD_TEST (test_texture_get_set_data, 0, TEST_REQUIREMENT_NPOT);
+  ADD_TEST (test_texture_get_set_data, 0, 0);
   ADD_TEST (test_texture_mipmap_get_set, 0, 0);
   ADD_TEST (test_atlas_migration, 0, 0);
   ADD_TEST (test_read_texture_formats, 0, 0);
-- 
1.7.11.3.g3c3efa5