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]>

2 files changed, 4 insertions, 2 deletions

diff --git a/src/mesa/state_tracker/st_atom_rasterizer.c b/src/mesa/state_tracker/st_atom_rasterizer.c
index 0383b8ac4ad..1f66b9d0597 100644
--- a/src/mesa/state_tracker/st_atom_rasterizer.c
+++ b/src/mesa/state_tracker/st_atom_rasterizer.c
@@ -294,7 +294,8 @@ st_update_rasterizer(struct st_context *st)
    }
 
    /* _NEW_TRANSFORM */
-   raster->depth_clip = !ctx->Transform.DepthClamp;
+   raster->depth_clip = !(ctx->Transform.DepthClampNear &&
+                          ctx->Transform.DepthClampFar);
    raster->clip_plane_enable = ctx->Transform.ClipPlanesEnabled;
    raster->clip_halfz = (ctx->Transform.ClipDepthMode == GL_ZERO_TO_ONE);
 
diff --git a/src/mesa/state_tracker/st_cb_drawpixels.c b/src/mesa/state_tracker/st_cb_drawpixels.c
index b8895684bc2..67bbb358500 100644
--- a/src/mesa/state_tracker/st_cb_drawpixels.c
+++ b/src/mesa/state_tracker/st_cb_drawpixels.c
@@ -677,7 +677,8 @@ draw_textured_quad(struct gl_context *ctx, GLint x, GLint y, GLfloat z,
                                         ctx->Color._ClampFragmentColor;
       rasterizer.half_pixel_center = 1;
       rasterizer.bottom_edge_rule = 1;
-      rasterizer.depth_clip = !ctx->Transform.DepthClamp;
+      rasterizer.depth_clip = !(ctx->Transform.DepthClampNear &&
+                                ctx->Transform.DepthClampFar);
       rasterizer.scissor = ctx->Scissor.EnableFlags;
       cso_set_rasterizer(cso, &rasterizer);
    }