[Mesa-dev] [PATCH 11/13] i965: Enable smooth points when multisampling without point sprites.

[Roland Scheidegger]

Am 19.02.2014 11:04, schrieb Kenneth Graunke:
> According to the "Point Multisample Rasterization" of the OpenGL
> specification (3.0 or later), smooth points are supposed to be enabled
> implicitly when multisampling, regardless of the GL_POINT_SMOOTH flag.
> 
> However, if GL_POINT_SPRITE is enabled, you get square points no matter
> what.  Core contexts always enable point sprites, so this effectively
> makes smooth points go away, even in the case of multisampling.
> 
> Fixes Piglit's EXT_framebuffer_multisample/point-smooth tests.
> (Yes, that's right folks, we actually have Piglit tests for this.)
> 
> Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
> ---
>  src/mesa/drivers/dri/i965/gen8_sf_state.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/gen8_sf_state.c b/src/mesa/drivers/dri/i965/gen8_sf_state.c
> index b31b17e..0693fee 100644
> --- a/src/mesa/drivers/dri/i965/gen8_sf_state.c
> +++ b/src/mesa/drivers/dri/i965/gen8_sf_state.c
> @@ -139,8 +139,11 @@ upload_sf(struct brw_context *brw)
>     if (!(ctx->VertexProgram.PointSizeEnabled || ctx->Point._Attenuated))
>        dw3 |= GEN6_SF_USE_STATE_POINT_WIDTH;
>  
> -   if (ctx->Point.SmoothFlag)
> +   /* _NEW_POINT | _NEW_MULTISAMPLE */
> +   if ((ctx->Point.SmoothFlag || ctx->Multisample._Enabled) &&
> +       !ctx->Point.PointSprite) {
>        dw3 |= GEN8_SF_SMOOTH_POINT_ENABLE;
> +   }
>  
>     dw3 |= GEN6_SF_LINE_AA_MODE_TRUE;
>  
> @@ -166,6 +169,7 @@ const struct brw_tracked_state gen8_sf_state = {
>        .mesa  = _NEW_LIGHT |
>                 _NEW_PROGRAM |
>                 _NEW_LINE |
> +               _NEW_MULTISAMPLE |
>                 _NEW_POINT,
>        .brw   = BRW_NEW_CONTEXT,
>        .cache = 0,
> 

Wow your hw can rasterize round points directly? At least ten years too
late to be useful but that's a slick feature!
In any case the logic looks right to me. I have not much idea about the
hw do you need to match the raster bit
(GEN8_RASTER_SMOOTH_POINT_ENABLE) for this too?

Roland