Check the flat qualifier from the correct member

[libs/gl.git] / source / core / buffer.h

diff --git a/source/core/buffer.h b/source/core/buffer.h
index 9737a2ea9323ddd0af5c44b3d51d595eff6fc6d1..9b1293615832a615318cf0212400c08b3af10961 100644 (file)
--- a/source/core/buffer.h
+++ b/source/core/buffer.h
@@ -15,42 +15,98 @@ 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: public BufferBackend
 {
        friend BufferBackend;
 
+public:
+       /**
+       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; }
+       };
+
 private:
-       unsigned size;
+       std::size_t size = 0;
+       BufferUsage usage = STATIC;
+       bool mapped = false;
 
 public:
-       Buffer();
-
-       /** Defines the storage size of the buffer.  Must be called before data can
-       be uploaded.  Storage cannot be changed once set. */
-       void storage(unsigned);
+       /** 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);
 
-       unsigned get_size() const { return size; }
+private:
+       void check_sub_data(std::size_t, std::size_t, const char *);
+
+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;
 
-       using BufferBackend::map;
-       using BufferBackend::unmap;
+       void *map();
+       bool unmap();
 
        using BufferBackend::set_debug_name;
 };