From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 26 Aug 2012 19:20:16 +0000 (+0300)
Subject: Improvements to Bufferable
X-Git-Url: http://git.tdb.fi/?a=commitdiff_plain;h=900cf40469972b1f32a6dbac95c42f46c3726fa8;p=libs%2Fgl.git

Improvements to Bufferable

Most members are now private, with read-only accessors, since the derived
classes should not modify them.  Some names were changed.

Add documentation to the class and all public/protected methods.
---

diff --git a/source/bufferable.cpp b/source/bufferable.cpp
index abd10b3a..60df3eec 100644
--- a/source/bufferable.cpp
+++ b/source/bufferable.cpp
@@ -9,7 +9,7 @@ namespace GL {
 
 Bufferable::Bufferable():
 	buffer(0),
-	buffer_offset(0),
+	offset(0),
 	next_in_buffer(0),
 	prev_in_buffer(0),
 	dirty(false)
@@ -33,10 +33,13 @@ void Bufferable::use_buffer(Buffer *buf, Bufferable *prev)
 	{
 		prev_in_buffer = prev;
 		if(prev_in_buffer)
+		{
+			next_in_buffer = prev_in_buffer->next_in_buffer;
 			prev_in_buffer->next_in_buffer = this;
+		}
 	}
 
-	update_buffer_offset();
+	update_offset();
 }
 
 void Bufferable::unlink_from_buffer()
@@ -46,43 +49,44 @@ void Bufferable::unlink_from_buffer()
 	if(next_in_buffer)
 	{
 		next_in_buffer->prev_in_buffer = prev_in_buffer;
-		next_in_buffer->update_buffer_offset();
+		next_in_buffer->update_offset();
 	}
 	prev_in_buffer = 0;
 	next_in_buffer = 0;
+	buffer = 0;
 }
 
-void Bufferable::update_buffer_offset()
+void Bufferable::update_offset()
 {
-	unsigned offset = 0;
+	unsigned new_offset = 0;
 	if(prev_in_buffer)
-		offset = prev_in_buffer->buffer_offset+prev_in_buffer->get_data_size();
+		new_offset = prev_in_buffer->offset+prev_in_buffer->get_data_size();
 
 	unsigned align = get_alignment();
-	offset += align-1;
-	offset -= offset%align;
-	if(offset!=buffer_offset)
+	new_offset += align-1;
+	new_offset -= new_offset%align;
+	if(new_offset!=offset)
 	{
-		buffer_offset = offset;
+		offset = new_offset;
 		dirty = true;
 		offset_changed();
 	}
 
 	if(next_in_buffer)
-		next_in_buffer->update_buffer_offset();
+		next_in_buffer->update_offset();
 
-	/* Do not resize the buffer here, as the offsets may change multiple times
-	before the buffer is actually used */
+	/* Do not resize the buffer here, as more bufferables may be added before
+	the buffer is actually used. */
 }
 
-void Bufferable::update_buffer_data() const
+void Bufferable::update_buffer() const
 {
-	if(buffer_offset+get_data_size()>=buffer->get_size())
+	if(offset+get_data_size()>=buffer->get_size())
 	{
 		const Bufferable *last = this;
 		for(; last->next_in_buffer; last=last->next_in_buffer) ;
 
-		unsigned total_size = last->buffer_offset+last->get_data_size();
+		unsigned total_size = last->offset+last->get_data_size();
 
 		if(total_size>buffer->get_size())
 		{
diff --git a/source/bufferable.h b/source/bufferable.h
index f5ae043c..0a30e80e 100644
--- 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;
 };
 
diff --git a/source/uniformblock.cpp b/source/uniformblock.cpp
index a87a6a42..6b9de269 100644
--- a/source/uniformblock.cpp
+++ b/source/uniformblock.cpp
@@ -41,7 +41,7 @@ void UniformBlock::offset_changed()
 void UniformBlock::upload_data() const
 {
 	if(!buf_range)
-		buf_range = new BufferRange(*buffer, buffer_offset, size);
+		buf_range = new BufferRange(*get_buffer(), get_offset(), size);
 	buf_range->data(&data[0]);
 }
 
@@ -53,7 +53,7 @@ void UniformBlock::attach(int index, const Uniform &uni)
 void UniformBlock::attach(const Program::UniformInfo &info, const Uniform &uni)
 {
 	uniforms[info.location] = &uni;
-	if(buffer)
+	if(get_buffer())
 	{
 		uni.store(info, &data[info.location]);
 		dirty = true;
@@ -62,13 +62,13 @@ void UniformBlock::attach(const Program::UniformInfo &info, const Uniform &uni)
 
 void UniformBlock::apply(int index) const
 {
-	if((index>=0) != (buffer!=0))
+	if((index>=0) != (get_buffer()!=0))
 		throw invalid_operation("UniformBlock::apply");
 
-	if(buffer)
+	if(get_buffer())
 	{
 		if(dirty)
-			update_buffer_data();
+			update_buffer();
 		buf_range->bind_to(UNIFORM_BUFFER, index);
 	}
 	else