Improvements to Bufferable

[libs/gl.git] / source / bufferable.h

diff --git a/source/bufferable.h b/source/bufferable.h
index f5ae043cb5144b498cf08d389248f7a66f25eefa..0a30e80e817e8343b374094651008a7d03935714 100644 (file)
--- a/source/bufferable.h
+++ b/source/bufferable.h
@@ -6,31 +6,60 @@ namespace GL {
 
 class Buffer;
 
+/**
+Base class for things that can store data in buffers.  Supports buffer sharing.
+A dirty flag is provided for derived classes.  It should be set when the data
+in the buffer is considered out of date, and is cleared by Bufferable after
+uploading fresh data to the buffer.
+*/
 class Bufferable
 {
-protected:
+private:
        Buffer *buffer;
-       unsigned buffer_offset;
+       unsigned offset;
        Bufferable *next_in_buffer;
        Bufferable *prev_in_buffer;
+protected:
        mutable bool dirty;
 
+protected:
        Bufferable();
 public:
        virtual ~Bufferable();
 
-       void use_buffer(Buffer *, Bufferable * = 0);
+       /** Sets the buffer to use.  If prev is not null, it must use the same
+       buffer, and this object is inserted after it. */
+       void use_buffer(Buffer *buf, Bufferable *prev = 0);
+
 private:
        void unlink_from_buffer();
 
 protected:
+       /** Returns the buffer in which the data is stored. */
+       Buffer *get_buffer() const { return buffer; }
+
+       /** Returns the amount of data to be stored in the buffer, in bytes. */
        virtual unsigned get_data_size() const = 0;
+
+       /** Returns the alignment required for the data, in bytes.  The offset is
+       guaranteed to be a multiple of this. */
        virtual unsigned get_alignment() const { return 1; }
 
-       void update_buffer_offset();
+       /** Updates the offsets for the chain so that data from different objects
+       does not overlap.  Should be called if either data size or alignment
+       changes. */
+       void update_offset();
+
+       /** Returns the offset where the data should be uploaded. */
+       unsigned get_offset() const { return offset; }
+
+       /** Called when the offset for the data has changed. */
        virtual void offset_changed() { }
 
-       void update_buffer_data() const;
+       /** Resizes the buffer if necessary and calls upload_data(). */
+       void update_buffer() const;
+
+       /** Uploads data to the buffer. */
        virtual void upload_data() const = 0;
 };