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Re: [Gnu3dkit-discuss] G3DKit.info - renderer questions


From: Philippe C . D . Robert
Subject: Re: [Gnu3dkit-discuss] G3DKit.info - renderer questions
Date: Thu, 31 Oct 2002 13:01:52 +0100

On Thursday, October 31, 2002, at 04:10  Uhr, Brent Gulanowski wrote:
On Wednesday, October 30, 2002, at 05:23 PM, Philippe C.D. Robert wrote:

My terminology here is:

o [action] a highlevel "job" to be performed on the scene graph, ie. culling data for the active frustum. This is thus generic.

o [task] a specific low-level "job" performed by the render engine, ie. switching a state (simple) or drawing arbitrary geometry (complex). This is thus specific.

Do you think this is a bad choice? I can see both possibilities, as long as it is used consistently...:-)

I'm pretty sure that, wherever you slice it, the word "action" means some particular activity, usually a well-defined activity or process. An action has no ambiguity. It also has little or no implicit impact on a state. It may have no consequences at all. A task is different in both ways -- it usually does not define the particular process followed to complete the task (which may be actions, or may be sub-tasks which are themselves composed of specific actions), and it does imply a meaningful change of state. There's a grey area between them, but in this case, I recommend swapping the terms.

Well, if you ie. have a look at Inventor then you see that there a SoAction is described as follows:

"SoAction is the abstract base class for all actions. Classes derived from SoAction define operations to be applied at each node encountered during traversal of a scene graph. The function that gets called to implement the action for a particular node type is determined by a lookup table in the global database."

The SoGLRenderAction class for example traverses a scene graph and renders it using the OpenGL graphics library. Thus I'd rather keep the terminology, otherwise it gets confusing...

Anyone?

-Phil
--
Philippe C.D. Robert
http://www.nice.ch/~phip





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