From a4f59a729cb9d8183ad8fc050d7bc163abfd55e8 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Fri, 24 Aug 2012 10:25:52 +0300
Subject: [PATCH] Improve binding of buffers

Add a set_current function, as seen in some other classes.

Buffer type support is now also checked in bind_to.
---
 source/buffer.cpp | 35 ++++++++++++++++++++++-------------
 source/buffer.h   |  3 ++-
 2 files changed, 24 insertions(+), 14 deletions(-)

diff --git a/source/buffer.cpp b/source/buffer.cpp
index c19f3727..1762b204 100644
--- a/source/buffer.cpp
+++ b/source/buffer.cpp
@@ -15,9 +15,7 @@ Buffer::Buffer(BufferType t):
 	usage(STATIC_DRAW),
 	size(0)
 {
-	static RequireExtension _req_vbo("GL_ARB_vertex_buffer_object");
-	if(type==PIXEL_PACK_BUFFER || type==PIXEL_UNPACK_BUFFER)
-		static RequireExtension _req_pbo("GL_ARB_pixel_buffer_object");
+	require_buffer_type(type);
 
 	glGenBuffersARB(1, &id);
 }
@@ -27,6 +25,13 @@ Buffer::~Buffer()
 	glDeleteBuffersARB(1, &id);
 }
 
+void Buffer::require_buffer_type(BufferType type)
+{
+	static RequireExtension _req_vbo("GL_ARB_vertex_buffer_object");
+	if(type==PIXEL_PACK_BUFFER || type==PIXEL_UNPACK_BUFFER)
+		static RequireExtension _req_pbo("GL_ARB_pixel_buffer_object");
+}
+
 void Buffer::set_usage(BufferUsage u)
 {
 	usage = u;
@@ -51,22 +56,16 @@ void Buffer::sub_data(unsigned off, unsigned sz, const void *d)
 
 void Buffer::bind_to(BufferType t) const
 {
-	const Buffer *&ptr = binding(t);
-	if(ptr!=this)
-	{
+	if(t!=type)
+		require_buffer_type(t);
+	if(set_current(t, this))
 		glBindBufferARB(t, id);
-		ptr = this;
-	}
 }
 
 void Buffer::unbind_from(BufferType type)
 {
-	const Buffer *&ptr = binding(type);
-	if(ptr)
-	{
+	if(set_current(type, 0))
 		glBindBufferARB(type, 0);
-		ptr = 0;
-	}
 }
 
 const Buffer *&Buffer::binding(BufferType type)
@@ -81,6 +80,16 @@ const Buffer *&Buffer::binding(BufferType type)
 	}
 }
 
+bool Buffer::set_current(BufferType type, const Buffer *buf)
+{
+	const Buffer *&ptr = binding(type);
+	if(ptr==buf)
+		return false;
+
+	ptr = buf;
+	return true;
+}
+
 void Buffer::restore(const Buffer *buf, BufferType type)
 {
 	if(buf!=current(type))
diff --git a/source/buffer.h b/source/buffer.h
index d8a8419c..117f4ea6 100644
--- a/source/buffer.h
+++ b/source/buffer.h
@@ -47,7 +47,7 @@ public:
 	~Buffer();
 
 private:
-	const Buffer *maybe_bind() const;
+	static void require_buffer_type(BufferType);
 
 public:
 	/** Sets the usage hint of the buffer.  It will take effect the next time
@@ -77,6 +77,7 @@ public:
 	static void unbind_from(BufferType);
 private:
 	static const Buffer *&binding(BufferType);
+	static bool set_current(BufferType, const Buffer *);
 	static void restore(const Buffer *, BufferType);
 };
 
-- 
2.45.2