X-Git-Url: http://git.tdb.fi/?p=libs%2Fgl.git;a=blobdiff_plain;f=source%2Fcore%2Fbuffer.h;h=9b1293615832a615318cf0212400c08b3af10961;hp=9144afaed3d1682f28efd8076988c8e815a977db;hb=HEAD;hpb=ada4b7614137221b64a00f31fde1498064e9fb19

diff --git a/source/core/buffer.h b/source/core/buffer.h
index 9144afae..9b129361 100644
--- a/source/core/buffer.h
+++ b/source/core/buffer.h
@@ -3,8 +3,7 @@
 
 #include <stdexcept>
 #include <string>
-#include <vector>
-#include "gl.h"
+#include "buffer_backend.h"
 
 namespace Msp {
 namespace GL {
@@ -16,54 +15,100 @@ public:
 	virtual ~buffer_too_small() throw() { }
 };
 
-class BufferRange;
+enum BufferUsage
+{
+	STATIC,
+	STREAMING
+};
 
 /**
-A buffer for storing data in GL memory.  Putting vertex and index data in
-buffers can improve rendering performance.  The VertexArray, Mesh and
-UniformBlock classes contain built-in support for buffers.
+Stores data in GPU memory.
+
+Memory must be allocated for the buffer by calling storage().  Contents can
+then be modified either synchronously with the data() and sub_data() functions,
+or asynchronously by memory-mapping the buffer.
+
+Buffers can have a static or streaming usage pattern.  Streaming buffers can be
+memory mapped for less update overhead, but memory space is more limited.  If
+the buffer is updated only rarely, static is recommended.
+
+Applications normally don't need to deal with Buffers directly.  They're
+managed by other classes such as Mesh and ProgramData.
 */
-class Buffer
+class Buffer: public BufferBackend
 {
-private:
-	unsigned id;
-	unsigned size;
-
-	static Buffer *scratch_binding;
+	friend BufferBackend;
 
 public:
-	Buffer();
-	~Buffer();
+	/**
+	An RAII handle for asynchronously writing data into a buffer.
+	*/
+	class AsyncTransfer: public NonCopyable
+	{
+		friend BufferBackend;
+		friend class Buffer;
+
+	private:
+		Buffer *buffer = 0;
+		std::size_t offset = 0;
+		std::size_t size = 0;
+		void *dest_addr = 0;
+
+		AsyncTransfer(Buffer &, std::size_t, std::size_t);
+	public:
+		AsyncTransfer() = default;
+		AsyncTransfer(AsyncTransfer &&);
+		AsyncTransfer &operator=(AsyncTransfer &&);
+		~AsyncTransfer();
+
+	private:
+		void allocate();
+		void finalize();
+
+	public:
+		/** Returns an address for writing the data.  It should not be used
+		beyond the lifetime of the object. */
+		void *get_address() { return dest_addr; }
+	};
 
-	/** Returns the OpenGL ID of the buffer.  For internal use only. */
-	unsigned get_id() const { return id; }
+private:
+	std::size_t size = 0;
+	BufferUsage usage = STATIC;
+	bool mapped = false;
 
-	/** Defines the storage size of the buffer.  Must be called before data can
-	be uploaded.  Storage cannot be changed once set. */
-	void storage(unsigned);
+public:
+	/** Sets storage size and usage pattern and allocates memory for the buffer.
+	Size and usage cannot be changed once set. */
+	void storage(std::size_t, BufferUsage);
 
-	/** Uploads data into the buffer, completely replacing any previous
-	contents.  Storage must be defined beforehand.  The data must have size
-	matching the defined storage. */
+	/** Replaces contents of the entire buffer.  Allocated storage must exist.
+	The data must have size matching the defined storage. */
 	void data(const void *);
 
-	/** Overwrites part of the buffer data with new data.  Storage must be
-	defined beforehand. */
-	void sub_data(unsigned, unsigned, const void *);
+	/** Replaces a range of bytes in the buffer.  Allocated storage must exist.
+	The range must be fully inside the buffer. */
+	void sub_data(std::size_t, std::size_t, const void *);
+
+	/** Creates an asynchronous transfer for writing data to a range of bytes in
+	the buffer.  While the transfer is pending, the state of the buffer region
+	is indeterminate. */
+	AsyncTransfer sub_data_async(std::size_t, std::size_t);
+
+private:
+	void check_sub_data(std::size_t, std::size_t, const char *);
 
-	unsigned get_size() const { return size; }
+public:
+	std::size_t get_size() const { return size; }
+	using BufferBackend::get_multiplicity;
+	std::size_t get_total_size() const { return size*get_multiplicity(); }
+	BufferUsage get_usage() const { return usage; }
 
-	void require_size(unsigned) const;
+	void require_size(std::size_t) const;
 
 	void *map();
 	bool unmap();
 
-	void set_debug_name(const std::string &);
-
-private:
-	void bind_scratch();
-public:
-	static void unbind_scratch();
+	using BufferBackend::set_debug_name;
 };
 
 } // namespace GL