Notify Renderables about the start and end of a frame

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

diff --git a/source/renderable.h b/source/renderable.h
index 3432a87ee77ed4db3c72600061127bef767c768d..b53fa9ac839307347bb614db7052dcfbe5a7a8cb 100644 (file)
--- a/source/renderable.h
+++ b/source/renderable.h
@@ -16,6 +16,12 @@ 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.
+
+The setup_frame and finish_frame methods provide a mechanism for performing
+once-per-frame operations.  This is most useful for effects, which may need to
+do auxiliary rendering.  With complex rendering hierarchies, these methods may
+be called multiple times for one frame, but it's guaranteed that no rendering
+will occur before a setup_frame call or after a finish_frame call.
 */
 class Renderable
 {
@@ -32,6 +38,12 @@ public:
        matrix exists. */
        virtual const Matrix *get_matrix() const { return 0; }
 
+       /** Called when starting to render a new frame. */
+       virtual void setup_frame() const { }
+
+       /** Called when a complete frame has been rendered. */
+       virtual void finish_frame() const { }
+
        /** Renders the renderable without a renderer.  This can be convenient in
        some simple cases, but most renderables don't need to implement this
        method. */