[virglrenderer-devel] [PATCH] virgl: Add method to query supported MSAA samples and positions

[Jakob Bornecrantz]

On 2018-06-25 15:57, Gert Wollny wrote:
> Query the number of supported samples and the sample position and
> store these to the caps.v2 structure. We support only up to 16 samples.
> This implementation requires a GL host backend.
> 


This patch uses functions that are not available in GLES causing qemu to 
crash on startup with this patch applied.

vrend_formats also seems to have two space as indentations instead of 
the rest of the files 3, not sure what is the way forward here.

Cheers, Jakob.


> Signed-off-by: Gert Wollny <gert.wollny at collabora.com>
> ---
> This patch needs another patch against mesa/virgl.
> 
>   src/virgl_hw.h       |  1 +
>   src/vrend_formats.c  | 48 +++++++++++++++++++++++++++++++++++++++++++-
>   src/vrend_renderer.c |  2 +-
>   src/vrend_renderer.h |  3 +++
>   4 files changed, 52 insertions(+), 2 deletions(-)
> 
> diff --git a/src/virgl_hw.h b/src/virgl_hw.h
> index 27b1a25..84bdfaa 100644
> --- a/src/virgl_hw.h
> +++ b/src/virgl_hw.h
> @@ -312,6 +312,7 @@ struct virgl_caps_v2 {
>           uint32_t uniform_buffer_offset_alignment;
>           uint32_t shader_buffer_offset_alignment;
>           uint32_t capability_bits;
> +        uint32_t sample_locations[8];
>   };
>   
>   union virgl_caps {
> diff --git a/src/vrend_formats.c b/src/vrend_formats.c
> index 0bb23c4..d1e18a6 100644
> --- a/src/vrend_formats.c
> +++ b/src/vrend_formats.c
> @@ -467,4 +467,50 @@ bool vrend_is_canonical_format(enum pipe_format format)
>      default:
>         return false;
>      }
> -}
> \ No newline at end of file
> +}
> +
> +unsigned vrend_renderer_query_multisample_caps(unsigned max_samples, struct virgl_caps_v2 *caps)
> +{
> +   GLuint tex;
> +   GLuint fbo;
> +   GLenum status;
> +
> +   uint i;
> +   uint max_samples_confirmed = 1;
> +   uint test_num_samples[4] = {2,4,8,16};
> +   int offsets[4] = {0,1,2,4};
> +
> +   glGenTextures( 1, &tex );
> +   glGenFramebuffers( 1, &fbo );
> +
> +   memset(caps->sample_locations, 0, 8 * sizeof(uint32_t));
> +
> +   for (int i = 0; i < 4 && test_num_samples[i] <= max_samples; ++i) {
> +
> +      glBindTexture( GL_TEXTURE_2D_MULTISAMPLE, tex );
> +      glTexImage2DMultisample( GL_TEXTURE_2D_MULTISAMPLE, test_num_samples[i], GL_RGBA32F, 10, 10, GL_TRUE);
> +      status = glGetError();
> +
> +      if (status == GL_NO_ERROR) {
> +         glBindFramebuffer( GL_FRAMEBUFFER, fbo );
> +         glFramebufferTexture2D( GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D_MULTISAMPLE, tex, 0 );
> +         status = glCheckFramebufferStatus( GL_FRAMEBUFFER );
> +         if (status == GL_FRAMEBUFFER_COMPLETE) {
> +            max_samples_confirmed = test_num_samples[i];
> +
> +            for (uint k = 0; k < test_num_samples[i]; ++k) {
> +               float msp[2];
> +               uint32_t compressed;
> +               glGetMultisamplefv(GL_SAMPLE_POSITION, k, msp);
> +               compressed = ((unsigned)(floor(msp[0] * 16.0f)) & 0xf) << 4;
> +               compressed |= ((unsigned)(floor(msp[1] * 16.0f)) & 0xf);
> +               caps->sample_locations[offsets[i] + (k >> 2)] |= compressed  << (8 * (k & 3));
> +            }
> +         }
> +      }
> +   }
> +
> +   glDeleteFramebuffers( 1, &fbo );
> +   glDeleteTextures( 1, &tex );
> +   return max_samples_confirmed;
> +}
> diff --git a/src/vrend_renderer.c b/src/vrend_renderer.c
> index 8690eb2..7074cad 100644
> --- a/src/vrend_renderer.c
> +++ b/src/vrend_renderer.c
> @@ -7142,7 +7142,7 @@ static bool vrend_renderer_fill_caps_common(uint32_t set, UNUSED uint32_t versio
>      caps->v1.max_render_targets = vrend_state.max_draw_buffers;
>   
>      glGetIntegerv(GL_MAX_SAMPLES, &max);
> -   caps->v1.max_samples = max;
> +   caps->v1.max_samples = vrend_renderer_query_multisample_caps(max, &caps->v2);
>   
>   
>      /* All of the formats are common. */
> diff --git a/src/vrend_renderer.h b/src/vrend_renderer.h
> index badf2b1..254edc7 100644
> --- a/src/vrend_renderer.h
> +++ b/src/vrend_renderer.h
> @@ -390,6 +390,9 @@ void vrend_renderer_reset(void);
>   int vrend_renderer_get_poll_fd(void);
>   void vrend_decode_reset(bool ctx_0_only);
>   
> +unsigned vrend_renderer_query_multisample_caps(unsigned max_samples,
> +                                               struct virgl_caps_v2 *caps);
> +
>   struct gl_version {
>      uint32_t major;
>      uint32_t minor;
>