[udig-devel] RenderContext for scenegraph is a good idea

[Jody Garnett <jody.garnett@xxxxxxxxx>]

Further clarification - I may of got the class names wrong. I recall
RenderExecutor, RenderCreator and RenderManager.

> I don't really see why you said there is no need to extend Renderer(Impl)... It's the RenderManager that creates Renderers (via RenderCreator), and I need a Renderer knowing how to create a javax.j3d.Shape3D from an org.opengis.Feature.
>
> What you seem to have in mind in plugging into the very end of the 2D rendering pipeline by providing a specialized Graphics2D which creates 3D objects instead. That might work in principle, but I would lose information, as there is no way to tell which 2D draw primitives come from the same feature.

There are two stages to rendering; matching Layers with Renderers - I
do not think we need to change this decision making process at all (we
may have to implement additional renderers; and we may have to add
some more information to the RenderMetrics - but the idea of defining
the layers seperate from the code that does the work of visualizing
them is sound).

Where I got you confused was in the technical tradeoffs with making
use of the GeoTools StreamingRenderer. I agree you will need to make a
uDig Renderer for drawing features into your scene graph.

Then I got excited and talked about different ways you could reuse the
GeoTools streaming Renderer (and thus make use of the style layer
descriptor data structure etc...). Sorry for the distraction.

In terms of the render( graphics2d ) method - we are going to hit that
from printing; if your renderer does not support this then we better
make sure the RenderingMetrics indicates that it is not a suitable
choice when we go to print.

For the render( progressmonitor) method - this is the one you want. I
know the implementations you look at now focus on grabbing a raster
out of the RenderContext().

Your implementations are not going to do that - they may choose to
store a scene graph data structure on the graphics context? Then your
rendering code can add to that scene graph? The actual specific way
you want to do this is up to you.

Jody