From e4d6832d315791f2d973a20443cd5f3c01ec01c8 Mon Sep 17 00:00:00 2001
From: Jamie Reece Wilson <me@reece.sx>
Date: Sat, 17 Aug 2024 15:55:29 +0100
Subject: [PATCH] [*] SM3.0 fixes

---
 spirv_hlsl.cpp | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/spirv_hlsl.cpp b/spirv_hlsl.cpp
index 46fc1768..031b4d44 100644
--- a/spirv_hlsl.cpp
+++ b/spirv_hlsl.cpp
@@ -783,6 +783,9 @@ void CompilerHLSL::emit_builtin_inputs_in_struct()
 			break;
 
 		case BuiltInPrimitiveId:
+			if (legacy)
+				SPIRV_CROSS_THROW("Primitive ID not supported in SM 3.0 or lower.");
+
 			type = "uint";
 			semantic = "SV_PrimitiveID";
 			break;
@@ -830,8 +833,16 @@ void CompilerHLSL::emit_builtin_inputs_in_struct()
 			break;
 
 		case BuiltInFrontFacing:
-			type = "bool";
-			semantic = "SV_IsFrontFace";
+            if (legacy)
+			{
+				type = "float";
+				semantic = "VFACE";
+            }
+            else
+			{
+				type = "bool";
+				semantic = "SV_IsFrontFace";
+			}
 			break;
 
 		case BuiltInViewIndex:
@@ -3146,6 +3157,20 @@ void CompilerHLSL::emit_hlsl_entry_point()
 			}
 			break;
 
+            
+
+		case BuiltInFrontFacing:
+        {
+			if (legacy)
+				statement(builtin, " = bool(stage_input.", builtin, " > 0.0 ? true : false);");
+			else
+			{
+				statement(builtin, " = int(stage_input.", builtin, ");");
+			}
+			break;
+        }
+
+
 		case BuiltInVertexId:
 		case BuiltInVertexIndex:
 		case BuiltInInstanceIndex: