[Mesa-dev] [RFC][PATCH 5/5] 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 | 21 ++++++++++++++++---
 src/mesa/drivers/dri/i965/intel_extensions.c  |  1 +
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/genX_state_upload.c b/src/mesa/drivers/dri/i965/genX_state_upload.c
index ea5ad55be5..75d9bd2b9b 100644
--- a/src/mesa/drivers/dri/i965/genX_state_upload.c
+++ b/src/mesa/drivers/dri/i965/genX_state_upload.c
@@ -2341,6 +2341,12 @@ genX(upload_cc_viewport)(struct brw_context *brw)
       if (ctx->Transform.DepthClamp) {
          ccv.MinimumDepth = MIN2(vp->Near, vp->Far);
          ccv.MaximumDepth = MAX2(vp->Near, vp->Far);
+      } 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;
@@ -4603,15 +4609,24 @@ genX(upload_raster)(struct brw_context *brw)
       /* _NEW_SCISSOR */
       raster.ScissorRectangleEnable = ctx->Scissor.EnableFlags;
 
+#if GEN_GEN < 9
       /* _NEW_TRANSFORM */
       if (!ctx->Transform.DepthClamp) {
+         raster.ViewportZClipTestEnable = true;
+      }
+#endif
+
 #if GEN_GEN >= 9
-         raster.ViewportZFarClipTestEnable = true;
+      if (!ctx->Transform.DepthClampNear) {
          raster.ViewportZNearClipTestEnable = true;
-#else
-         raster.ViewportZClipTestEnable = true;
+      }
 #endif
+
+#if GEN_GEN >= 9
+      if (!ctx->Transform.DepthClampFar) {
+         raster.ViewportZFarClipTestEnable = true;
       }
+#endif
 
       /* BRW_NEW_CONSERVATIVE_RASTERIZATION */
 #if GEN_GEN >= 9
diff --git a/src/mesa/drivers/dri/i965/intel_extensions.c b/src/mesa/drivers/dri/i965/intel_extensions.c
index 2e28445ae3..0b7ce7b368 100644
--- a/src/mesa/drivers/dri/i965/intel_extensions.c
+++ b/src/mesa/drivers/dri/i965/intel_extensions.c
@@ -300,6 +300,7 @@ intelInitExtensions(struct gl_context *ctx)
    }
 
    if (devinfo->gen >= 9) {
+      ctx->Extensions.AMD_depth_clamp_separate = true;
       ctx->Extensions.ANDROID_extension_pack_es31a = true;
       ctx->Extensions.ARB_shader_stencil_export = true;
       ctx->Extensions.KHR_blend_equation_advanced_coherent = true;
-- 
2.17.1