[Mesa-dev] [PATCH 1/2] swr: [rasterizer core] allow an OpenGL driver to specify halfz clipping

[Ilia Mirkin]

On Wed, Nov 9, 2016 at 1:21 AM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
> With ARB_clip_control, GL may also do 0..1 depth clipping, not just
> -1..1. For backwards compatibility, preserve the existing driver type
> check for DX as well.

Oh. An even better idea would be to update SwrSetRasterizer to
magically flip that bit on when driverType == DX at the API level. And
drop all that driver type stuff from the core otherwise. IMHO that's
much cleaner. Let me know if you think this will cause problems.

At least in gallium, we've avoided making any GL vs DX distinctions.
It seems like a good thing to do in swr core as well.

Cheers,

  -ilia

>
> Signed-off-by: Ilia Mirkin <imirkin at alum.mit.edu>
> ---
>  src/gallium/drivers/swr/rasterizer/core/clip.h  | 6 +++---
>  src/gallium/drivers/swr/rasterizer/core/state.h | 1 +
>  2 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/src/gallium/drivers/swr/rasterizer/core/clip.h b/src/gallium/drivers/swr/rasterizer/core/clip.h
> index 43bc522..78dbcf0 100644
> --- a/src/gallium/drivers/swr/rasterizer/core/clip.h
> +++ b/src/gallium/drivers/swr/rasterizer/core/clip.h
> @@ -90,7 +90,7 @@ void ComputeClipCodes(DRIVER_TYPE type, const API_STATE& state, const simdvector
>      {
>          // FRUSTUM_NEAR
>          // DX clips depth [0..w], GL clips [-w..w]
> -        if (type == DX)
> +        if (type == DX || state.rastState.clipHalfZ)
>          {
>              vRes = _simd_cmplt_ps(vertex.z, _simd_setzero_ps());
>          }
> @@ -640,7 +640,7 @@ private:
>          case FRUSTUM_BOTTOM:    t = ComputeInterpFactor(_simd_sub_ps(v1[3], v1[1]), _simd_sub_ps(v2[3], v2[1])); break;
>          case FRUSTUM_NEAR:
>              // DX Znear plane is 0, GL is -w
> -            if (this->driverType == DX)
> +            if (this->driverType == DX || this->state.rastState.clipHalfZ)
>              {
>                  t = ComputeInterpFactor(v1[2], v2[2]);
>              }
> @@ -708,7 +708,7 @@ private:
>          case FRUSTUM_RIGHT:     return _simd_cmple_ps(v[0], v[3]);
>          case FRUSTUM_TOP:       return _simd_cmpge_ps(v[1], _simd_mul_ps(v[3], _simd_set1_ps(-1.0f)));
>          case FRUSTUM_BOTTOM:    return _simd_cmple_ps(v[1], v[3]);
> -        case FRUSTUM_NEAR:      return _simd_cmpge_ps(v[2], this->driverType == DX ? _simd_setzero_ps() : _simd_mul_ps(v[3], _simd_set1_ps(-1.0f)));
> +        case FRUSTUM_NEAR:      return _simd_cmpge_ps(v[2], this->driverType == DX || this->state.rastState.clipHalfZ ? _simd_setzero_ps() : _simd_mul_ps(v[3], _simd_set1_ps(-1.0f)));
>          case FRUSTUM_FAR:       return _simd_cmple_ps(v[2], v[3]);
>          default:
>              SWR_ASSERT(false, "invalid clipping plane: %d", ClippingPlane);
> diff --git a/src/gallium/drivers/swr/rasterizer/core/state.h b/src/gallium/drivers/swr/rasterizer/core/state.h
> index 93e4565..5ee12e8 100644
> --- a/src/gallium/drivers/swr/rasterizer/core/state.h
> +++ b/src/gallium/drivers/swr/rasterizer/core/state.h
> @@ -932,6 +932,7 @@ struct SWR_RASTSTATE
>      uint32_t frontWinding           : 1;
>      uint32_t scissorEnable          : 1;
>      uint32_t depthClipEnable        : 1;
> +    uint32_t clipHalfZ              : 1;
>      uint32_t pointParam             : 1;
>      uint32_t pointSpriteEnable      : 1;
>      uint32_t pointSpriteTopOrigin   : 1;
> --
> 2.7.3
>