[Cogl] [PATCH 3/4] gles: Support the GL_EXT_texture_format_BGRA8888 extension

[Robert Bragg]

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

On Thu, Mar 22, 2012 at 5:32 PM, Neil Roberts <neil at linux.intel.com> wrote:

> This extension allows an application to upload data in BGRA format. We
> can use this to avoid a conversion in Cogl whenever it is given BGRA
> data. This is quite useful when uploading data generated by Cairo
> because at least on little-endian architectures that ends up as BGRA.
>
> The patch just makes the pixel_format_to_gl implementation return
> GL_BGRA_EXT for the data format and internal format whenever
> COGL_PIXEL_FORMAT_BGRA_8888{,_PRE} is used.
>
> A small caveat with this patch is that once a texture is created as
> GL_BGRA, when later using glTexSubImage2D to update the texture it
> must always be given data as GL_BGRA. Currently this just works out
> because we store the internal format of a texture as a CoglPixelFormat
> and we already swizzle the data if it does not match exactly on GLES.
> However if we later switch to using a different enum for internal
> formats then we might lose the ability to store the component ordering
> so we'll have to think of another way to do this.
> ---
>  cogl/cogl-internal.h         |    3 ++-
>  cogl/cogl-texture.c          |    9 +++++++++
>  cogl/driver/gles/cogl-gles.c |   21 +++++++++++++++++++--
>  3 files changed, 30 insertions(+), 3 deletions(-)
>
> diff --git a/cogl/cogl-internal.h b/cogl/cogl-internal.h
> index 9019859..4f53cc3 100644
> --- a/cogl/cogl-internal.h
> +++ b/cogl/cogl-internal.h
> @@ -100,7 +100,8 @@ typedef enum
>   COGL_PRIVATE_FEATURE_PBOS = 1L<<5,
>   COGL_PRIVATE_FEATURE_VBOS = 1L<<6,
>   COGL_PRIVATE_FEATURE_EXT_PACKED_DEPTH_STENCIL = 1L<<7,
> -  COGL_PRIVATE_FEATURE_OES_PACKED_DEPTH_STENCIL = 1L<<8
> +  COGL_PRIVATE_FEATURE_OES_PACKED_DEPTH_STENCIL = 1L<<8,
> +  COGL_PRIVATE_FEATURE_TEXTURE_FORMAT_BGRA8888 = 1L<<9
>  } CoglPrivateFeatureFlags;
>
>  /* Sometimes when evaluating pipelines, either during comparisons or
> diff --git a/cogl/cogl-texture.c b/cogl/cogl-texture.c
> index 27cbb64..ab07f91 100644
> --- a/cogl/cogl-texture.c
> +++ b/cogl/cogl-texture.c
> @@ -166,6 +166,15 @@ _cogl_texture_determine_internal_format
> (CoglPixelFormat src_format,
>         return src_format;
>     }
>   else
> +    /* XXX: It might be nice to make this match the component ordering
> +       of the source format when the formats are otherwise the same
> +       because on GL there is no way to specify the ordering of the
> +       internal format. However when using GLES with the
> +       GL_EXT_texture_format_BGRA8888 the order of the internal format
> +       becomes important because it must exactly match the format of
> +       the uploaded data. That means that if someone creates a texture
> +       with some RGBA data and then later tries to upload BGRA data we
> +       do actually have to swizzle the components */
>     return dst_format;
>  }
>
> diff --git a/cogl/driver/gles/cogl-gles.c b/cogl/driver/gles/cogl-gles.c
> index d4c5968..102a19f 100644
> --- a/cogl/driver/gles/cogl-gles.c
> +++ b/cogl/driver/gles/cogl-gles.c
> @@ -69,6 +69,22 @@ _cogl_driver_pixel_format_to_gl (CoglContext *context,
>       gltype = GL_UNSIGNED_BYTE;
>       break;
>
> +    case COGL_PIXEL_FORMAT_BGRA_8888:
> +    case COGL_PIXEL_FORMAT_BGRA_8888_PRE:
> +      /* There is an extension to support this format */
> +      if ((context->private_feature_flags &
> +           COGL_PRIVATE_FEATURE_TEXTURE_FORMAT_BGRA8888))
> +        {
> +          /* For some reason the extension says you have to specify
> +             BGRA for the internal format too */
> +          glintformat = GL_BGRA_EXT;
> +          glformat = GL_BGRA_EXT;
> +          gltype = GL_UNSIGNED_BYTE;
> +          required_format = format;
> +          break;
> +        }
> +      /* flow through */
> +
>       /* Just one 24-bit ordering supported */
>     case COGL_PIXEL_FORMAT_RGB_888:
>     case COGL_PIXEL_FORMAT_BGR_888:
> @@ -81,8 +97,6 @@ _cogl_driver_pixel_format_to_gl (CoglContext *context,
>       /* Just one 32-bit ordering supported */
>     case COGL_PIXEL_FORMAT_RGBA_8888:
>     case COGL_PIXEL_FORMAT_RGBA_8888_PRE:
> -    case COGL_PIXEL_FORMAT_BGRA_8888:
> -    case COGL_PIXEL_FORMAT_BGRA_8888_PRE:
>     case COGL_PIXEL_FORMAT_ARGB_8888:
>     case COGL_PIXEL_FORMAT_ARGB_8888_PRE:
>     case COGL_PIXEL_FORMAT_ABGR_8888:
> @@ -276,6 +290,9 @@ _cogl_driver_update_features (CoglContext *context,
>   if (_cogl_check_extension ("GL_OES_packed_depth_stencil", gl_extensions))
>     private_flags |= COGL_PRIVATE_FEATURE_OES_PACKED_DEPTH_STENCIL;
>
> +  if (_cogl_check_extension ("GL_EXT_texture_format_BGRA8888",
> gl_extensions))
> +    private_flags |= COGL_PRIVATE_FEATURE_TEXTURE_FORMAT_BGRA8888;
> +
>   /* Cache features */
>   context->private_feature_flags |= private_flags;
>   context->feature_flags |= flags;
> --
> 1.7.3.16.g9464b
>
> _______________________________________________
> Cogl mailing list
> Cogl at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/cogl
>
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