From 02feac06937ec4e8e122a833b4903ccf0bd6d030 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sat, 21 Dec 2013 11:58:57 +0200
Subject: [PATCH] Add support for multiple binding points in the RAII binders

---
 source/bindable.h     | 69 +++++++++++++++++++++++++++++++++++++++----
 source/bufferable.cpp |  8 ++---
 source/mesh.cpp       |  3 +-
 3 files changed, 66 insertions(+), 14 deletions(-)

diff --git a/source/bindable.h b/source/bindable.h
index f534d7af..8651c70e 100644
--- a/source/bindable.h
+++ b/source/bindable.h
@@ -71,8 +71,9 @@ does nothing upon destruction.
 class Bind
 {
 private:
-	typedef void CleanupFunc();
+	typedef void CleanupFunc(int);
 
+	int slot;
 	CleanupFunc *cleanup;
 
 public:
@@ -85,6 +86,15 @@ public:
 	template<typename T>
 	Bind(const T &o) { init(&o); }
 
+	template<typename T, typename S>
+	Bind(T *o, S s) { init(o, s); }
+
+	template<typename T, typename S>
+	Bind(const T *o, S s) { init(o, s); }
+
+	template<typename T, typename S>
+	Bind(const T &o, S s) { init(&o, s); }
+
 private:
 	template<typename T>
 	void init(const T *o)
@@ -96,14 +106,29 @@ private:
 			T::unbind();
 	}
 
+	template<typename T, typename S>
+	void init(const T *o, S s)
+	{
+		cleanup = (o ? &unbind_from<T, S> : 0);
+		slot = s;
+		if(o)
+			o->bind_to(s);
+		else
+			T::unbind_from(s);
+	}
+
 public:
 	~Bind()
-	{ if(cleanup) cleanup(); }
+	{ if(cleanup) cleanup(slot); }
 
 private:
 	template<typename T>
-	static void unbind()
+	static void unbind(int)
 	{ T::unbind(); }
+
+	template<typename T, typename S>
+	static void unbind_from(int s)
+	{ T::unbind_from(static_cast<S>(s)); }
 };
 
 
@@ -113,9 +138,10 @@ Similar to Bind, but restores previous binding upon destruction.
 class BindRestore
 {
 private:
-	typedef void CleanupFunc(const void *);
+	typedef void CleanupFunc(const void *, int);
 
 	const void *old;
+	int slot;
 	CleanupFunc *cleanup;
 
 public:
@@ -128,6 +154,15 @@ public:
 	template<typename T>
 	BindRestore(const T &o) { init(&o); }
 
+	template<typename T, typename S>
+	BindRestore(T *o, S s) { init(o, s); }
+
+	template<typename T, typename S>
+	BindRestore(const T *o, S s) { init(o, s); }
+
+	template<typename T, typename S>
+	BindRestore(const T &o, S s) { init(&o, s); }
+
 private:
 	template<typename T>
 	void init(T *o)
@@ -140,19 +175,41 @@ private:
 			T::unbind();
 	}
 
+	template<typename T, typename S>
+	void init(T *o, S s)
+	{
+		old = T::current(s);
+		slot = s;
+		cleanup = (o!=old ? &restore_to<T, S> : 0);
+		if(o)
+			o->bind_to(s);
+		else if(old)
+			T::unbind_from(s);
+	}
+
 public:
 	~BindRestore()
-	{ if(cleanup) cleanup(old); }
+	{ if(cleanup) cleanup(old, slot); }
 
 private:
 	template<typename T>
-	static void restore(const void *o)
+	static void restore(const void *o, int)
 	{
 		if(o)
 			reinterpret_cast<const T *>(o)->bind();
 		else
 			T::unbind();
 	}
+
+	template<typename T, typename S>
+	static void restore_to(const void *o, int si)
+	{
+		S s = static_cast<S>(si);
+		if(o)
+			reinterpret_cast<const T *>(o)->bind_to(s);
+		else
+			T::unbind_from(s);
+	}
 };
 
 } // namespace GL
diff --git a/source/bufferable.cpp b/source/bufferable.cpp
index 1f6122e0..eb3f1c00 100644
--- a/source/bufferable.cpp
+++ b/source/bufferable.cpp
@@ -1,4 +1,5 @@
 #include <stdexcept>
+#include "bindable.h"
 #include "buffer.h"
 #include "bufferable.h"
 
@@ -81,8 +82,7 @@ void Bufferable::update_offset()
 
 void Bufferable::update_buffer() const
 {
-	const Buffer *old_buffer = Buffer::current(buffer->get_type());
-	buffer->bind();
+	BindRestore bind(buffer, buffer->get_type());
 	if(offset+get_data_size()>=buffer->get_size())
 	{
 		const Bufferable *last = this;
@@ -102,10 +102,6 @@ void Bufferable::update_buffer() const
 	}
 
 	upload_data();
-	if(old_buffer)
-		old_buffer->bind_to(buffer->get_type());
-	else
-		buffer->unbind();
 	dirty = false;
 }
 
diff --git a/source/mesh.cpp b/source/mesh.cpp
index 26d66044..c9819ae9 100644
--- a/source/mesh.cpp
+++ b/source/mesh.cpp
@@ -88,8 +88,7 @@ void Mesh::refresh() const
 		if(dirty&2)
 		{
 			glBindVertexArray(vao_id);
-			BufferAlias<ARRAY_BUFFER> vbuf_alias(*vbuf);
-			Bind bind_vbuf(vbuf_alias);
+			Bind bind_vbuf(vbuf, ARRAY_BUFFER);
 
 			const VertexFormat &fmt = vertices.get_format();
 			unsigned stride = get_stride(fmt)*sizeof(float);
-- 
2.43.0