[Mesa-dev] [PATCH] mesa: Clamp ValueMask to [0, 255].

[Jason Ekstrand]

Should ref also get clamped?

On Dec 17, 2016 1:03 AM, "Kenneth Graunke" <kenneth at whitecape.org> wrote:

> Commit b8b1d83c71fd148d2fd84afdc20c0aa367114f92 partially fixed
> dEQP-GLES3.functional.state_query.integers.stencil*value*mask*getfloat
> by changing the initial value masks from 32-bit ~0 (0xFFFFFFFF) to 0xFF.
>
> However, the application can call glStencilFunc and related functions
> to set a new value mask, which is a 32-bit quantity.  The application
> might specify 0xFFFFFFFF, bringing us back to the original problem.
>
> In particular, dEQP's state reset code seems to do this, so the tests
> still fail when running the entire suite from one process, rather than
> running the tests individually.
>
> This patch clamps the value masks to 0xFF when setting them.  Higher
> bits have no effect on an 8-bit stencil buffer anyway.
>
> This might break apps that set a value mask then try to query it back
> with glGet and expect to get the same value.  I'm unclear whether apps
> can reasonably expect that anyway.
>
> Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
> ---
>  src/mesa/main/stencil.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/src/mesa/main/stencil.c b/src/mesa/main/stencil.c
> index b303bb7..608c564 100644
> --- a/src/mesa/main/stencil.c
> +++ b/src/mesa/main/stencil.c
> @@ -161,7 +161,7 @@ _mesa_StencilFuncSeparateATI( GLenum frontfunc, GLenum
> backfunc, GLint ref, GLui
>     ctx->Stencil.Function[0]  = frontfunc;
>     ctx->Stencil.Function[1]  = backfunc;
>     ctx->Stencil.Ref[0]       = ctx->Stencil.Ref[1]       = ref;
> -   ctx->Stencil.ValueMask[0] = ctx->Stencil.ValueMask[1] = mask;
> +   ctx->Stencil.ValueMask[0] = ctx->Stencil.ValueMask[1] = mask & 0xFF;
>     if (ctx->Driver.StencilFuncSeparate) {
>        ctx->Driver.StencilFuncSeparate(ctx, GL_FRONT,
>                                        frontfunc, ref, mask);
> @@ -206,7 +206,7 @@ _mesa_StencilFunc( GLenum func, GLint ref, GLuint mask
> )
>        FLUSH_VERTICES(ctx, _NEW_STENCIL);
>        ctx->Stencil.Function[face] = func;
>        ctx->Stencil.Ref[face] = ref;
> -      ctx->Stencil.ValueMask[face] = mask;
> +      ctx->Stencil.ValueMask[face] = mask & 0xFF;
>
>        /* Only propagate the change to the driver if EXT_stencil_two_side
>         * is enabled.
> @@ -227,7 +227,7 @@ _mesa_StencilFunc( GLenum func, GLint ref, GLuint mask
> )
>        FLUSH_VERTICES(ctx, _NEW_STENCIL);
>        ctx->Stencil.Function[0]  = ctx->Stencil.Function[1]  = func;
>        ctx->Stencil.Ref[0]       = ctx->Stencil.Ref[1]       = ref;
> -      ctx->Stencil.ValueMask[0] = ctx->Stencil.ValueMask[1] = mask;
> +      ctx->Stencil.ValueMask[0] = ctx->Stencil.ValueMask[1] = mask & 0xFF;
>        if (ctx->Driver.StencilFuncSeparate) {
>           ctx->Driver.StencilFuncSeparate(ctx,
>                                          ((ctx->Stencil.TestTwoSide)
> @@ -472,13 +472,13 @@ _mesa_StencilFuncSeparate(GLenum face, GLenum func,
> GLint ref, GLuint mask)
>        /* set front */
>        ctx->Stencil.Function[0] = func;
>        ctx->Stencil.Ref[0] = ref;
> -      ctx->Stencil.ValueMask[0] = mask;
> +      ctx->Stencil.ValueMask[0] = mask & 0xFF;
>     }
>     if (face != GL_FRONT) {
>        /* set back */
>        ctx->Stencil.Function[1] = func;
>        ctx->Stencil.Ref[1] = ref;
> -      ctx->Stencil.ValueMask[1] = mask;
> +      ctx->Stencil.ValueMask[1] = mask & 0xFF;
>     }
>     if (ctx->Driver.StencilFuncSeparate) {
>        ctx->Driver.StencilFuncSeparate(ctx, face, func, ref, mask);
> --
> 2.10.2
>
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