[Cogl] [PATCH 2/3] Also flip the virtual coordinates when iterating spans

[Robert Bragg]

This looks good to land to me:

Reviewed-by: Robert Bragg <robert at linux.intel.com>

thanks,
- Robert

On Tue, Dec 11, 2012 at 2:56 PM, Neil Roberts <neil at linux.intel.com> wrote:
> _cogl_texture_spans_foreach_in_region first swaps over the texture
> coordinates if they are flipped so that it can always iterate in a
> positive direction. It sets a flag so that it will remember that the
> coordinates are flipped. Before invoking the callback it is meant to
> reflip the coordinates so that the callee doesn't need to be aware of
> the flipping. However it was only flipping the sub-texture coordinates
> and not the virtual coordinates. This was causing sliced textures to
> draw their slice rectangles with the wrong geometry.
> test-backface-culling was failing because of this.
> ---
>  cogl/cogl-texture.c               | 15 +++++++++------
>  tests/conform/test-conform-main.c |  2 +-
>  2 files changed, 10 insertions(+), 7 deletions(-)
>
> diff --git a/cogl/cogl-texture.c b/cogl/cogl-texture.c
> index 1c9da68..15d7bbd 100644
> --- a/cogl/cogl-texture.c
> +++ b/cogl/cogl-texture.c
> @@ -1180,6 +1180,7 @@ _cogl_texture_spans_foreach_in_region (CoglSpan *x_spans,
>    CoglSpanIter iter_x;
>    CoglSpanIter iter_y;
>    float slice_coords[4];
> +  float span_virtual_coords[4];
>
>    /* Iterate the y axis of the virtual rectangle */
>    for (_cogl_span_iter_begin (&iter_y,
> @@ -1196,11 +1197,15 @@ _cogl_texture_spans_foreach_in_region (CoglSpan *x_spans,
>          {
>            slice_coords[1] = iter_y.intersect_end;
>            slice_coords[3] = iter_y.intersect_start;
> +          span_virtual_coords[1] = iter_y.intersect_end;
> +          span_virtual_coords[3] = iter_y.intersect_start;
>          }
>        else
>          {
>            slice_coords[1] = iter_y.intersect_start;
>            slice_coords[3] = iter_y.intersect_end;
> +          span_virtual_coords[1] = iter_y.intersect_start;
> +          span_virtual_coords[3] = iter_y.intersect_end;
>          }
>
>        /* Map the current intersection to normalized slice coordinates */
> @@ -1219,17 +1224,20 @@ _cogl_texture_spans_foreach_in_region (CoglSpan *x_spans,
>            _cogl_span_iter_next (&iter_x))
>          {
>            CoglTexture *span_tex;
> -          float span_virtual_coords[4];
>
>            if (iter_x.flipped)
>              {
>                slice_coords[0] = iter_x.intersect_end;
>                slice_coords[2] = iter_x.intersect_start;
> +              span_virtual_coords[0] = iter_x.intersect_end;
> +              span_virtual_coords[2] = iter_x.intersect_start;
>              }
>            else
>              {
>                slice_coords[0] = iter_x.intersect_start;
>                slice_coords[2] = iter_x.intersect_end;
> +              span_virtual_coords[0] = iter_x.intersect_start;
> +              span_virtual_coords[2] = iter_x.intersect_end;
>              }
>
>            /* Map the current intersection to normalized slice coordinates */
> @@ -1239,11 +1247,6 @@ _cogl_texture_spans_foreach_in_region (CoglSpan *x_spans,
>           /* Pluck out the cogl texture for this span */
>            span_tex = textures[iter_y.index * n_x_spans + iter_x.index];
>
> -          span_virtual_coords[0] = iter_x.intersect_start;
> -          span_virtual_coords[1] = iter_y.intersect_start;
> -          span_virtual_coords[2] = iter_x.intersect_end;
> -          span_virtual_coords[3] = iter_y.intersect_end;
> -
>            callback (COGL_TEXTURE (span_tex),
>                      slice_coords,
>                      span_virtual_coords,
> diff --git a/tests/conform/test-conform-main.c b/tests/conform/test-conform-main.c
> index 5acf2e5..8e30b84 100644
> --- a/tests/conform/test-conform-main.c
> +++ b/tests/conform/test-conform-main.c
> @@ -58,7 +58,7 @@ main (int argc, char **argv)
>    ADD_TEST (test_path, 0, 0);
>    ADD_TEST (test_depth_test, 0, 0);
>    ADD_TEST (test_color_mask, 0, 0);
> -  ADD_TEST (test_backface_culling, 0, TEST_REQUIREMENT_NPOT);
> +  ADD_TEST (test_backface_culling, 0, 0);
>    ADD_TEST (test_layer_remove, 0, 0);
>
>    ADD_TEST (test_sparse_pipeline, 0, 0);
> --
> 1.7.11.3.g3c3efa5
>
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