[Mesa-dev] [PATCH v3] meta/GetTexSubImage: Account for GL_PACK_SKIP_IMAGES on compressed textures

[Kenneth Graunke]

From: Eduardo Lima Mitev <elima at igalia.com>

This option was being ignored when packing compressed 3D and cube textures.

Fixes CTS test (on gen8+):
* GL45-CTS.gtf32.GL3Tests.packed_pixels.packed_pixels_pixelstore

v2: Drop API checks.
v3 (Ken): Just apply the existing code in more cases.
---
 src/mesa/drivers/common/meta.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

Hey Eduardo,

It looks like the existing code already tries to handle SkipImages - but
we weren't applying it for 3D and cubemap textures.  I found a spec quote
in the narrative for GetTexImage that indicates we need to do it for those
as well.

What do you think of this version?  I preserved your authorship as I wanted
you to get the credit for this bugfix - I just typed it up so that I could
make sure it actually fixed the test, and since I had it typed up, I figured
I'd send it out to save you some time...

 --Ken

diff --git a/src/mesa/drivers/common/meta.c b/src/mesa/drivers/common/meta.c
index 5ab1e6c..99c85cf 100644
--- a/src/mesa/drivers/common/meta.c
+++ b/src/mesa/drivers/common/meta.c
@@ -3243,8 +3243,20 @@ _mesa_meta_GetTexSubImage(struct gl_context *ctx,
 
       for (slice = 0; slice < depth; slice++) {
          void *dst;
-         if (texImage->TexObject->Target == GL_TEXTURE_2D_ARRAY
-             || texImage->TexObject->Target == GL_TEXTURE_CUBE_MAP_ARRAY) {
+         /* Section 8.11.4 (Texture Image Queries) of the GL 4.5 spec says:
+          *
+          *    "For three-dimensional, two-dimensional array, cube map array,
+          *     and cube map textures pixel storage operations are applied as
+          *     if the image were two-dimensional, except that the additional
+          *     pixel storage state values PACK_IMAGE_HEIGHT and
+          *     PACK_SKIP_IMAGES are applied. The correspondence of texels to
+          *     memory locations is as defined for TexImage3D in section 8.5."
+          */
+         switch (texImage->TexObject->Target) {
+         case GL_TEXTURE_3D:
+         case GL_TEXTURE_2D_ARRAY:
+         case GL_TEXTURE_CUBE_MAP:
+         case GL_TEXTURE_CUBE_MAP_ARRAY: {
             /* Setup pixel packing.  SkipPixels and SkipRows will be applied
              * in the decompress_texture_image() function's call to
              * glReadPixels but we need to compute the dest slice's address
@@ -3255,9 +3267,11 @@ _mesa_meta_GetTexSubImage(struct gl_context *ctx,
             packing.SkipRows = 0;
             dst = _mesa_image_address3d(&packing, pixels, width, height,
                                         format, type, slice, 0, 0);
+            break;
          }
-         else {
+         default:
             dst = pixels;
+            break;
          }
          result = decompress_texture_image(ctx, texImage, slice,
                                            xoffset, yoffset, width, height,
-- 
2.10.2