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 b642738e0e96ef370a5e748701be071998e2de54..a12b3373e601664bddf75d60bb930d56bbe26833 100644 (file)
--- a/source/core/buffer.h
+++ b/source/core/buffer.h
@@ -15,6 +15,12 @@ public:
        virtual ~buffer_too_small() throw() { }
 };
 
+enum BufferUsage
+{
+       STATIC,
+       STREAMING
+};
+
 /**
 Stores data in GPU memory.
 
@@ -22,6 +28,10 @@ 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.
 */
@@ -31,11 +41,13 @@ class Buffer: public BufferBackend
 
 private:
        std::size_t size = 0;
+       BufferUsage usage = STATIC;
+       bool mapped = false;
 
 public:
-       /** Sets the storage size and allocates memory for the buffer.  Size cannot
-       be changed once set. */
-       void storage(std::size_t);
+       /** 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);
 
        /** Replaces contents of the entire buffer.  Allocated storage must exist.
        The data must have size matching the defined storage. */
@@ -46,6 +58,7 @@ public:
        void sub_data(std::size_t, std::size_t, const void *);
 
        std::size_t get_size() const { return size; }
+       BufferUsage get_usage() const { return usage; }
 
        void require_size(std::size_t) const;