[Mesa-dev] [PATCH v3] mesa: handle a bunch of formats in IMPLEMENTATION_COLOR_READ_*

[Tomeu Vizoso]

On 31 May 2018 at 00:25, Eric Anholt <eric at anholt.net> wrote:
> Tomeu Vizoso <tomeu.vizoso at collabora.com> writes:
>
>> Virgl could save a lot of work converting buffers in the host side
>> between formats if Mesa supported a bunch of other formats when reading
>> pixels.
>>
>> This commit adds cases to handle specific formats so that the values
>> reported by the two calls match more closely the underlying native
>> formats.
>>
>> In GLES is important that IMPLEMENTATION_COLOR_READ_* return the native
>> format and data type because the spec only allows reading with those,
>> besides GL_RGBA or GL_RGBA_INTEGER.
>>
>> Additionally, because virgl currently doesn't implement such
>> conversions, this commit fixes several tests in
>> dEQP-GLES3.functional.fbo.color.clear.*, when using virgl in the guest
>> side.
>>
>> The logic is based on knowledge that is shared with
>> _mesa_format_matches_format_and_type() but we cannot assert that the
>> results match as we don't have all the starting information at both
>> points. So leave the assert out and hope CI comes soon to save us all.
>>
>> v2: * Let R10G10B10A2_UINT fall back to GL_RGBA_INTEGER (Eric Anholt)
>>     * Assert with _mesa_format_matches_format_and_type (Eric Anholt)
>>
>> v3: * Remove the assert, as it won't be reliable (Eric Anholt)
>>
>> Signed-off-by: Tomeu Vizoso <tomeu.vizoso at collabora.com>
>> ---
>>  src/mesa/main/framebuffer.c | 68 +++++++++++++++++++++++--------------
>>  1 file changed, 43 insertions(+), 25 deletions(-)
>>
>> diff --git a/src/mesa/main/framebuffer.c b/src/mesa/main/framebuffer.c
>> index 8e751b453b75..b1a544b5646d 100644
>> --- a/src/mesa/main/framebuffer.c
>> +++ b/src/mesa/main/framebuffer.c
>> @@ -834,18 +834,52 @@ _mesa_get_color_read_format(struct gl_context *ctx,
>>     }
>>     else {
>>        const mesa_format format = fb->_ColorReadBuffer->Format;
>> -      const GLenum data_type = _mesa_get_format_datatype(format);
>> +      GLenum data_type;
>> +      GLuint comps;
>>
>> -      if (format == MESA_FORMAT_B8G8R8A8_UNORM)
>> +      _mesa_uncompressed_format_to_type_and_comps(format, &data_type, &comps);
>> +
>> +      switch (format) {
>> +      case MESA_FORMAT_RGBA_UINT8:
>> +         return GL_RGBA_INTEGER;
>> +      case MESA_FORMAT_B8G8R8A8_UNORM:
>>           return GL_BGRA;
>> -      else if (format == MESA_FORMAT_B5G6R5_UNORM)
>> +      case MESA_FORMAT_B5G6R5_UNORM:
>> +      case MESA_FORMAT_R11G11B10_FLOAT:
>>           return GL_RGB;
>> -      else if (format == MESA_FORMAT_R_UNORM8)
>> +      case MESA_FORMAT_RG_FLOAT32:
>> +      case MESA_FORMAT_RG_FLOAT16:
>> +      case MESA_FORMAT_R8G8_UNORM:
>> +         return GL_RG;
>> +      case MESA_FORMAT_RG_SINT32:
>> +      case MESA_FORMAT_RG_UINT32:
>> +      case MESA_FORMAT_RG_SINT16:
>> +      case MESA_FORMAT_RG_UINT16:
>> +      case MESA_FORMAT_RG_SINT8:
>> +      case MESA_FORMAT_RG_UINT8:
>> +         return GL_RG_INTEGER;
>> +      case MESA_FORMAT_R_FLOAT32:
>> +      case MESA_FORMAT_R_FLOAT16:
>> +      case MESA_FORMAT_R_UNORM8:
>>           return GL_RED;
>> +      case MESA_FORMAT_R_SINT32:
>> +      case MESA_FORMAT_R_UINT32:
>> +      case MESA_FORMAT_R_SINT16:
>> +      case MESA_FORMAT_R_UINT16:
>> +      case MESA_FORMAT_R_SINT8:
>> +      case MESA_FORMAT_R_UINT8:
>> +         return GL_RED_INTEGER;
>> +      default:
>> +         break;
>> +      }
>>
>>        switch (data_type) {
>>        case GL_UNSIGNED_INT:
>> +      case GL_UNSIGNED_INT_2_10_10_10_REV:
>> +      case GL_UNSIGNED_SHORT:
>
> Formats like MESA_FORMAT_R_UNORM16 return GL_UNSIGNED_SHORT, but they
> should be returning GL_RGBA, right?  Similar for SNORM, and similar for BYTE
> cases.  Maybe _mesa_format_is_integer() could help you here?

You are right that it shouldn't be GL_RGBA_INTEGER as per the current
code, but I think it should be GL_RED and not GL_RGBA.

I will add those Mesa formats to the switch case, as
_mesa_format_is_integer() isn't enough to tell.

Thanks,

Tomeu

>
>>        case GL_INT:
>> +      case GL_SHORT:
>> +      case GL_BYTE:
>>           return GL_RGBA_INTEGER;
>>        default:
>>           return GL_RGBA;
>
>
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