mesa: Add support for AMD_depth_clamp_separate

Enable _mesa_PushAttrib() and _mesa_PopAttrib() to handle
GL_DEPTH_CLAMP_NEAR_AMD and GL_DEPTH_CLAMP_FAR_AMD tokens.

Remove DepthClamp, because DepthClampNear + DepthClampFar replaces it,
as suggested by Marek Olsak.

Driver that enables AMD_depth_clamp_separate will only ever look at
DepthClampNear and DepthClampFar, as suggested by Ian Romanick.

v2: 1) Remove unnecessary parentheses (Marek Olsak)
    2) if AMD_depth_clamp_separate is unsupported, TEST_AND_UPDATE
       GL_DEPTH_CLAMP only (Marek Olsak)
    3) Clamp against near and far plane separately (Marek Olsak)
    4) Clip point separately for near and far Z clipping plane (Marek
       Olsak)

v3: Clamp raster position zw to the range [min(n,f), 0] for near plane
    and [0, max(n,f)] for far plane (Marek Olsak)

v4: Use MIN2 and MAX2 instead of CLAMP (Marek Olsak)

Signed-off-by: Sagar Ghuge <[email protected]>
Reviewed-by: Ian Romanick <[email protected]>
Reviewed-by: Marek Olšák <[email protected]>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/mesa/swrast/s_span.c b/src/mesa/swrast/s_span.c
index 87b72e81970..f50b549a97f 100644
--- a/src/mesa/swrast/s_span.c
+++ b/src/mesa/swrast/s_span.c
@@ -1219,7 +1219,7 @@ _swrast_write_rgba_span( struct gl_context *ctx, SWspan *span)
       if (!(span->arrayMask & SPAN_Z))
          _swrast_span_interpolate_z(ctx, span);
 
-      if (ctx->Transform.DepthClamp)
+      if (ctx->Transform.DepthClampNear && ctx->Transform.DepthClampFar)
 	 _swrast_depth_clamp_span(ctx, span);
 
       if (_mesa_stencil_is_enabled(ctx)) {