[Mesa-dev] [PATCH] meta: add pixel pack operations in glGetTexImage

[Brian Paul]

On 02/10/2012 02:39 PM, Anuj Phogat wrote:
> This patch adds the pixel pack operations in glGetTexImage for
> compressed textures with unsigned, normalized values. It also
> fixes the failures in intel oglconform pxstore-gettex due to
> following sub test cases:
>
>   - Test all mipmaps with byte swapping enabled
>   - Test all small mipmaps with all allowable alignment values
>   - Test subimage packing for all mipmap levels
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=40864
>
> Note: This is a candidate for stable branches
>
> Signed-off-by: Anuj Phogat<anuj.phogat at gmail.com>
> ---
>   src/mesa/drivers/common/meta.c |   55 +++++++++++++++++++++++++++++++++++++--
>   1 files changed, 52 insertions(+), 3 deletions(-)
>
> diff --git a/src/mesa/drivers/common/meta.c b/src/mesa/drivers/common/meta.c
> index aa5fef8..97c1912 100644
> --- a/src/mesa/drivers/common/meta.c
> +++ b/src/mesa/drivers/common/meta.c
> @@ -53,6 +53,7 @@
>   #include "main/pixel.h"
>   #include "main/pbo.h"
>   #include "main/polygon.h"
> +#include "main/pack.h"
>   #include "main/readpix.h"
>   #include "main/scissor.h"
>   #include "main/shaderapi.h"
> @@ -3438,6 +3439,14 @@ _mesa_meta_GetTexImage(struct gl_context *ctx,
>                          GLenum format, GLenum type, GLvoid *pixels,
>                          struct gl_texture_image *texImage)
>   {
> +   GLuint row;
> +   GLfloat *srcRow;
> +   void *tempImage, *dest;
> +   const GLuint width = texImage->Width;
> +   const GLuint height = texImage->Height;
> +   const GLint tempRowLength = 0;
> +   GLbitfield transferOps = 0x0;
> +
>      /* We can only use the decompress-with-blit method here if the texels are
>       * unsigned, normalized values.  We could handle signed and unnormalized
>       * with floating point renderbuffers...
> @@ -3445,14 +3454,54 @@ _mesa_meta_GetTexImage(struct gl_context *ctx,
>      if (_mesa_is_format_compressed(texImage->TexFormat)&&
>          _mesa_get_format_datatype(texImage->TexFormat)
>          == GL_UNSIGNED_NORMALIZED) {
> +
>         struct gl_texture_object *texObj = texImage->TexObject;
> -      const GLuint slice = 0; /* only 2D compressed textures for now */
> +      /* only 2D compressed textures for now */
> +      const GLuint slice = 0;
> +      const int dimensions = 2;
> +
> +      if (format == GL_LUMINANCE ||
> +          format == GL_LUMINANCE_ALPHA) {
> +         transferOps |= IMAGE_CLAMP_BIT;
> +      }
> +
> +      /* Allocate a temporary 2D RGBA float buffer */
> +      tempImage = malloc(width * height * 4 * sizeof(GLfloat));
> +      if (tempImage == NULL) {
> +         _mesa_error(ctx, GL_OUT_OF_MEMORY, "glGetTexImage");
> +         return;
> +      }
> +
>         /* Need to unlock the texture here to prevent deadlock... */
>         _mesa_unlock_texture(ctx, texObj);
> -      decompress_texture_image(ctx, texImage, slice, format, type, pixels,
> -                               ctx->Pack.RowLength);
> +
> +      /* Decompress in to temporary buffer with format = GL_RGBA,
> +       * type = GL_FLOAT and RowLength = 0 then pack in to user
> +       * supplied buffer
> +       */
> +      decompress_texture_image(ctx, texImage, slice, GL_RGBA, GL_FLOAT,
> +                               tempImage, tempRowLength);
>         /* ... and relock it */
>         _mesa_lock_texture(ctx, texObj);
> +
> +      srcRow = (GLfloat*) tempImage;
> +      for (row = 0; row<  height; row++) {
> +         dest = _mesa_image_address(dimensions,&ctx->Pack, pixels,
> +                                    width, height, format, type,
> +                                    0, row, 0);
> +         if (_mesa_is_integer_format(format)) {

I don't think the format can be integer-valued at this point if we 
tested for datatype = GL_UNSIGNED_NORMALIZED above.


> +            _mesa_pack_rgba_span_int(ctx, width, (GLuint (*)[4]) srcRow,
> +                                     format, type, dest);
> +         }
> +         else {
> +            _mesa_pack_rgba_span_float(ctx, width, (GLfloat (*)[4]) srcRow,
> +                                       format, type, dest,&ctx->Pack,
> +                                       transferOps);
> +         }
> +         srcRow += width * 4;
> +      }
> +
> +      free(tempImage);
>      }
>      else {
>         _mesa_get_teximage(ctx, format, type, pixels, texImage);


If the main problem here is the pixel store/pack operations, I think 
that another fix is much simpler:

First, let's remove the destRowLength parameter to 
decompress_texture_image().  We're just passing ctx->Pack.RowLength 
but then we assign that value to ctx->Pack.RowLength at line 3412. 
That's pointless.

Then, instead of calling _mesa_meta_begin(ctx, MESA_META_ALL) at line 
3277, use (MESA_META_ALL & ~MESA_META_PIXEL_STORE).  The current pixel 
store params will stay in effect and _mesa_ReadPixels() call at line 
3413 will apply them for us.

BTW, I think we could avoid some FBO resizing/reallocating if we 
change line 3295 to read:

  if (width > decompress->Width || height > decompress->Height) {


-Brian