[Mesa-dev] [PATCH 6/7] i965: add functional changes for AMD_depth_clamp_separate

[Sagar Ghuge]

Gen >= 9 have ability to control clamping of depth values separately at
near and far plane.

z_w is clamped to the range [min(n,f), 0] if clamping at near plane is
enabled, [0, max(n,f)] if clamping at far plane is enabled and [min(n,f)
max(n,f)] if clamping at both plane is enabled.

Signed-off-by: Sagar Ghuge <sagar.ghuge at intel.com>
---
 src/mesa/drivers/dri/i965/genX_state_upload.c | 23 +++++++++++++++----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/genX_state_upload.c b/src/mesa/drivers/dri/i965/genX_state_upload.c
index dc54cb67af..4e978bed91 100644
--- a/src/mesa/drivers/dri/i965/genX_state_upload.c
+++ b/src/mesa/drivers/dri/i965/genX_state_upload.c
@@ -2343,7 +2343,13 @@ genX(upload_cc_viewport)(struct brw_context *brw)
       if (ctx->Transform.DepthClampNear && ctx->Transform.DepthClampFar) {
          ccv.MinimumDepth = MIN2(vp->Near, vp->Far);
          ccv.MaximumDepth = MAX2(vp->Near, vp->Far);
-      } else {
+      } else if (ctx->Transform.DepthClampNear) {
+         ccv.MinimumDepth = MIN2(vp->Near, vp->Far);
+         ccv.MaximumDepth = 0.0;
+      } else if (ctx->Transform.DepthClampFar) {
+         ccv.MinimumDepth = 0.0;
+         ccv.MaximumDepth = MAX2(vp->Near, vp->Far);
+      }else {
          ccv.MinimumDepth = 0.0;
          ccv.MaximumDepth = 1.0;
       }
@@ -4607,16 +4613,23 @@ genX(upload_raster)(struct brw_context *brw)
       raster.ScissorRectangleEnable = ctx->Scissor.EnableFlags;
 
       /* _NEW_TRANSFORM */
+#if GEN_GEN < 9
       if (!(ctx->Transform.DepthClampNear &&
             ctx->Transform.DepthClampFar)) {
-#if GEN_GEN >= 9
-         raster.ViewportZFarClipTestEnable = true;
-         raster.ViewportZNearClipTestEnable = true;
-#else
          raster.ViewportZClipTestEnable = true;
+      }
 #endif
+
+#if GEN_GEN >= 9
+      if (!ctx->Transform.DepthClampNear) {
+         raster.ViewportZNearClipTestEnable = true;
       }
 
+      if (!ctx->Transform.DepthClampFar) {
+         raster.ViewportZFarClipTestEnable = true;
+      }
+#endif
+
       /* BRW_NEW_CONSERVATIVE_RASTERIZATION */
 #if GEN_GEN >= 9
       raster.ConservativeRasterizationEnable =
-- 
2.17.1