From fc5a3640bd7a007c2da025308e6d6a33402eb098 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Tue, 30 Mar 2021 16:40:52 +0300
Subject: [PATCH] Add some precondition checks to Program

Adding stages from multiple modules presents some difficulties in matching
the interfaces.
---
 source/core/program.cpp | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/source/core/program.cpp b/source/core/program.cpp
index 789fa324..c41976ed 100644
--- a/source/core/program.cpp
+++ b/source/core/program.cpp
@@ -80,6 +80,9 @@ Program::~Program()
 
 void Program::add_stages(const Module &mod, const map<string, int> &spec_values)
 {
+	if(!stage_ids.empty())
+		throw invalid_operation("Program::add_stages");
+
 	switch(mod.get_format())
 	{
 	case Module::GLSL: return add_glsl_stages(static_cast<const GlslModule &>(mod), spec_values);
@@ -220,6 +223,9 @@ void Program::bind_fragment_data(unsigned index, const string &name)
 
 void Program::link()
 {
+	if(stage_ids.empty())
+		throw invalid_operation("Program::link");
+
 	uniforms.clear();
 
 	glLinkProgram(id);
-- 
2.45.2