From 828ec85982c203a6d1c33e170d7740e3cfad1cbf Mon Sep 17 00:00:00 2001
From: Jake Turner <jake@evansturner.co.uk>
Date: Mon, 24 Nov 2025 14:09:07 +1300
Subject: [PATCH] Fix Spirv simulation of
 ImageSampleProjDrefExplicitLod/ImplicitLod

Divide the compare (Dref) value by q
---
 renderdoc/driver/vulkan/vk_shaderdebug.cpp | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/renderdoc/driver/vulkan/vk_shaderdebug.cpp b/renderdoc/driver/vulkan/vk_shaderdebug.cpp
index 8fbd6b9cf..355ed6e5d 100644
--- a/renderdoc/driver/vulkan/vk_shaderdebug.cpp
+++ b/renderdoc/driver/vulkan/vk_shaderdebug.cpp
@@ -1262,6 +1262,13 @@ public:
             uniformParams.ddy[i] = floatComp(ddyCalc, i);
           }
         }
+        if((opcode == rdcspv::Op::ImageSampleProjDrefExplicitLod) ||
+           (opcode == rdcspv::Op::ImageSampleProjDrefImplicitLod))
+        {
+          RDCASSERT(useCompare);
+          float q = floatComp(uv, coords);
+          uniformParams.compare /= q;
+        }
 
         break;
       }