X-Git-Url: http://git.tdb.fi/?a=blobdiff_plain;f=source%2Frenderable.h;h=2342ae288cfed9b4d8fa61f25bf932ae47058540;hb=904de4f7fd994886adbd3a6c03bc1b7c14ebc562;hp=c055cefa65b989047ff0b324ab53259204ac77c1;hpb=f14435e58bfa0fa697a06ba9a454bb30cd37d9d8;p=libs%2Fgl.git

diff --git a/source/renderable.h b/source/renderable.h
index c055cefa..2342ae28 100644
--- a/source/renderable.h
+++ b/source/renderable.h
@@ -9,6 +9,13 @@ namespace GL {
 
 class Renderer;
 
+/**
+Base class for renderable objects.  All Renderables must support rendering with
+a Renderer, and may optionally provide support for standalone rendering.
+
+The render methods take a Tag to identify a render pass.  It is most commonly
+used together with Techniques and Pipelines to implement multipass rendering.
+*/
 class Renderable
 {
 protected:
@@ -16,11 +23,18 @@ protected:
 public:
 	virtual ~Renderable() { }
 
-	/** Returns a key used for grouping Renderables in an InstanceScene. */
+	/** Returns a key used for grouping Renderables in an InstanceScene.  The
+	returned value is treated as opaque. */
 	virtual long get_instance_key() const { return 0; }
 
+	/** Renders the renderable without a renderer.  This can be convenient in
+	some simple cases, but most renderables don't need to implement this
+	method. */
 	virtual void render(const Tag & = Tag()) const;
-	virtual void render(Renderer &, const Tag & = Tag()) const;
+
+	/** Renders the renderable.  Implementors should take care to return the
+	renderer to the state it was in, for example by using Renderer::Push. */
+	virtual void render(Renderer &, const Tag & = Tag()) const = 0;
 };
 
 } // namespace Msp