flattening kills performance

[ZetronMan]

Since drwr is like the smartest person ever, let me just quote him from another thread:

@drwr

I don’t see anything wrong, but the other side of flattening is that once a node has been flattened, Panda must then render either all of the vertices in the node, or none of them. (Before flattening, Panda can eliminate those parts of the node that are outside the viewing frustum, but not after flattening.) So, if you flatten the whole world, suddenly Panda has to render the whole world every frame.

If your scene is simple enough that your graphics card can handle rendering the entire scene every frame, this isn’t a problem; but if you overwhelm your graphics card, you might need to reconsider your level of flattening.

You can use root.analyze() to get a report of how much geometry you’ve got beneath the root node, and how it is distributed. Try looking at it before and after flattening. It shouldn’t change (much) in the number of vertices; if it does, something’s wrong.

You can also see some of this in PStats–in PStats, you can see the number of vertices (and the number of Geoms) that are actually being sent to the graphics card. Before flattenStrong(), the number of vertices will be relatively low, and the number of Geoms will be relatively high. After flattenStrong(), the number of Geoms will be lower (because they have been combined together), while the number of vertices will increase (because Panda can no longer cull out individual pieces).

The trick is to find the balance point between Geoms and triangles that is appropriate for your graphics card.

[Help with closing primitives)