Add a usage parameter to Buffer

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

diff --git a/source/core/buffer.h b/source/core/buffer.h
index 0e1836888dfbdd083ce47fe4c9af5dbfe6bfa3a5..a12b3373e601664bddf75d60bb930d56bbe26833 100644 (file)
--- a/source/core/buffer.h
+++ b/source/core/buffer.h
@@ -3,7 +3,7 @@
 
 #include <stdexcept>
 #include <string>
-#include <vector>
+#include "buffer_backend.h"
 
 namespace Msp {
 namespace GL {
@@ -15,55 +15,57 @@ 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
 {
-       friend class PipelineState;
-       friend class Texture2D;
-       friend class VertexSetup;
+       friend BufferBackend;
 
 private:
-       unsigned id;
-       unsigned size;
-
-       static Buffer *scratch_binding;
+       std::size_t size = 0;
+       BufferUsage usage = STATIC;
+       bool mapped = false;
 
 public:
-       Buffer();
-       ~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 *);
-
-       unsigned get_size() const { return size; }
+       /** 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 *);
 
-       void require_size(unsigned) const;
+       std::size_t get_size() const { return size; }
+       BufferUsage get_usage() const { return usage; }
 
-       void *map();
-       bool unmap();
+       void require_size(std::size_t) const;
 
-       void set_debug_name(const std::string &);
+       using BufferBackend::map;
+       using BufferBackend::unmap;
 
-private:
-       void bind_scratch();
-public:
-       static void unbind_scratch();
+       using BufferBackend::set_debug_name;
 };
 
 } // namespace GL