From 8c379c40892fc0e11cf2d40f4784c6e6aa1a12d7 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Thu, 11 Nov 2021 00:35:45 +0200
Subject: [PATCH] Assign the same specialization constant IDs in all stages

---
 source/glsl/generate.cpp | 16 +++++++++++++---
 source/glsl/generate.h   |  1 +
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/source/glsl/generate.cpp b/source/glsl/generate.cpp
index ec51c19c..c82d1c6c 100644
--- a/source/glsl/generate.cpp
+++ b/source/glsl/generate.cpp
@@ -16,9 +16,16 @@ void ConstantIdAssigner::apply(Module &module, const Features &features)
 
 	for(VariableDeclaration *v: auto_constants)
 	{
-		unsigned id = hash32(v->name)%features.constant_id_range;
-		while(used_ids.count(id))
-			id = (id+1)%features.constant_id_range;
+		unsigned id;
+		auto j = existing_constants.find(v->name);
+		if(j!=existing_constants.end())
+			id = j->second;
+		else
+		{
+			id = hash32(v->name)%features.constant_id_range;
+			while(used_ids.count(id))
+				id = (id+1)%features.constant_id_range;
+		}
 
 		auto i = find_member(v->layout->qualifiers, string("constant_id"), &Layout::Qualifier::name);
 		if(i!=v->layout->qualifiers.end())
@@ -38,7 +45,10 @@ void ConstantIdAssigner::visit(VariableDeclaration &var)
 			if(i->value==-1)
 				auto_constants.push_back(&var);
 			else
+			{
+				existing_constants[var.name] = i->value;
 				used_ids.insert(i->value);
+			}
 		}
 	}
 }
diff --git a/source/glsl/generate.h b/source/glsl/generate.h
index fc58b2db..d828daa5 100644
--- a/source/glsl/generate.h
+++ b/source/glsl/generate.h
@@ -16,6 +16,7 @@ class ConstantIdAssigner: private TraversingVisitor
 {
 private:
 	std::set<unsigned> used_ids;
+	std::map<std::string, unsigned> existing_constants;
 	std::vector<VariableDeclaration *> auto_constants;
 
 public:
-- 
2.45.2