[Mesa-dev] [PATCH 1/1] mesa: stub the _mesa_StencilOp function.

[Brian Paul]

On 05/18/2012 05:24 AM, Oliver McFadden wrote:
> The device driver function table only implements StencilOpSeparate(),
> let's remove the obsolete 'todo' comment and code duplication.
>
> Signed-off-by: Oliver McFadden<oliver.mcfadden at linux.intel.com>
> ---
>   src/mesa/drivers/common/meta.c |    4 +-
>   src/mesa/main/stencil.c        |   75 ++++++---------------------------------
>   2 files changed, 14 insertions(+), 65 deletions(-)
>
> diff --git a/src/mesa/drivers/common/meta.c b/src/mesa/drivers/common/meta.c
> index 95336fc..42bbf9d 100644
> --- a/src/mesa/drivers/common/meta.c
> +++ b/src/mesa/drivers/common/meta.c
> @@ -2360,12 +2360,12 @@ _mesa_meta_DrawPixels(struct gl_context *ctx,
>         _mesa_set_enable(ctx, GL_STENCIL_TEST, GL_TRUE);
>
>         /* set all stencil bits to 0 */
> -      _mesa_StencilOp(GL_REPLACE, GL_REPLACE, GL_REPLACE);
> +      _mesa_StencilOpSeparate(ctx->Stencil.ActiveFace, GL_REPLACE, GL_REPLACE, GL_REPLACE);
>         _mesa_StencilFunc(GL_ALWAYS, 0, 255);
>         _mesa_DrawArrays(GL_TRIANGLE_FAN, 0, 4);
>
>         /* set stencil bits to 1 where needed */
> -      _mesa_StencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);
> +      _mesa_StencilOpSeparate(ctx->Stencil.ActiveFace, GL_KEEP, GL_KEEP, GL_REPLACE);
>
>         _mesa_BindProgram(GL_FRAGMENT_PROGRAM_ARB, drawpix->StencilFP);
>         _mesa_set_enable(ctx, GL_FRAGMENT_PROGRAM_ARB, GL_TRUE);
> diff --git a/src/mesa/main/stencil.c b/src/mesa/main/stencil.c
> index f47b57b..f051479 100644
> --- a/src/mesa/main/stencil.c
> +++ b/src/mesa/main/stencil.c
> @@ -314,70 +314,24 @@ _mesa_StencilMask( GLuint mask )
>    *
>    * Verifies the parameters and updates the respective fields in
>    * __struct gl_contextRec::Stencil. On change flushes the vertices and notifies the
> - * driver via the dd_function_table::StencilOp callback.
> + * driver via the dd_function_table::StencilOpSeparate callback.
>    */
>   void GLAPIENTRY
>   _mesa_StencilOp(GLenum fail, GLenum zfail, GLenum zpass)
>   {
>      GET_CURRENT_CONTEXT(ctx);
> -   const GLint face = ctx->Stencil.ActiveFace;
> -
> -   if (MESA_VERBOSE&  VERBOSE_API)
> -      _mesa_debug(ctx, "glStencilOp()\n");
> -
> -   ASSERT_OUTSIDE_BEGIN_END(ctx);
> -
> -   if (!validate_stencil_op(ctx, fail)) {
> -      _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOp(sfail)");
> -      return;
> -   }
> -   if (!validate_stencil_op(ctx, zfail)) {
> -      _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOp(zfail)");
> -      return;
> -   }
> -   if (!validate_stencil_op(ctx, zpass)) {
> -      _mesa_error(ctx, GL_INVALID_ENUM, "glStencilOp(zpass)");
> -      return;
> -   }
> -
> -   if (face != 0) {

Note: if face != 0, it must be 2 (there should be an assertion).  More 
below...


> -      /* only set active face state */
> -      if (ctx->Stencil.ZFailFunc[face] == zfail&&
> -          ctx->Stencil.ZPassFunc[face] == zpass&&
> -          ctx->Stencil.FailFunc[face] == fail)
> -         return;
> -      FLUSH_VERTICES(ctx, _NEW_STENCIL);
> -      ctx->Stencil.ZFailFunc[face] = zfail;
> -      ctx->Stencil.ZPassFunc[face] = zpass;
> -      ctx->Stencil.FailFunc[face] = fail;
> -
> -      /* Only propagate the change to the driver if EXT_stencil_two_side
> -       * is enabled.
> -       */
> -      if (ctx->Driver.StencilOpSeparate&&  ctx->Stencil.TestTwoSide) {
> -         ctx->Driver.StencilOpSeparate(ctx, GL_BACK, fail, zfail, zpass);
> -      }
> -   }
> -   else {
> -      /* set both front and back state */
> -      if (ctx->Stencil.ZFailFunc[0] == zfail&&
> -          ctx->Stencil.ZFailFunc[1] == zfail&&
> -          ctx->Stencil.ZPassFunc[0] == zpass&&
> -          ctx->Stencil.ZPassFunc[1] == zpass&&
> -          ctx->Stencil.FailFunc[0] == fail&&
> -          ctx->Stencil.FailFunc[1] == fail)
> -         return;
> -      FLUSH_VERTICES(ctx, _NEW_STENCIL);
> -      ctx->Stencil.ZFailFunc[0] = ctx->Stencil.ZFailFunc[1] = zfail;
> -      ctx->Stencil.ZPassFunc[0] = ctx->Stencil.ZPassFunc[1] = zpass;
> -      ctx->Stencil.FailFunc[0]  = ctx->Stencil.FailFunc[1]  = fail;
> -      if (ctx->Driver.StencilOpSeparate) {
> -         ctx->Driver.StencilOpSeparate(ctx,
> -				       ((ctx->Stencil.TestTwoSide)
> -					? GL_FRONT : GL_FRONT_AND_BACK),
> -                                       fail, zfail, zpass);
> +   GLenum face;
> +
> +   if (ctx->Stencil.TestTwoSide) {
> +      face = GL_FRONT_AND_BACK;
> +   } else {
> +      if (ctx->Stencil.ActiveFace == 0) {
> +	 face = GL_FRONT;
> +      } else {
> +	 face = GL_BACK;
>         }
>      }
> +   _mesa_StencilOpSeparate(face, fail, zfail, zpass);
>   }

I think there's something subtly different here.  As noted above, if 
face != 0 it must be 2 so we're setting the stencil[2] state.  But 
that never happens in _mesa_StencilOpSeparate().

It's all a bit confusing because two-sided stencil is treated 
differently between GL_EXT_stencil_two_side, GL_ATI_separate_stencil 
and OpenGL 2.0.

Maybe you can double-check this stuff.

-Brian