How to clean up render-to-texture?

Scripting Issues
1

There is this snippet in the manual for creating a render-to-texture:

mybuffer = base.win.makeTextureBuffer("My Buffer", 512, 512)
mytexture = mybuffer.getTexture()
mybuffer.setSort(-100)
mycamera = base.makeCamera(mybuffer)
myscene = NodePath("My Scene")
mycamera.node().setScene(myscene)

Then I can assign mytexture to geometry as desired, e.g.

mymodel = loader.loadModel("...")
mymodel.setTexture(mytexture)

Once I have no more use for mytexture and nothing is currently using it (e.g. I did mymodel.removeNode()), what should I do to completely clean up the particular render-to-texture setup behind it?

2

Use base.closeWindow to close the buffer.

3

Unfortunatelly I didn’t get that. If I try something like base.closeWindow(mybuffer) I get the error:

...
  File "/usr/share/panda3d/direct/showbase/ShowBase.py", line 650, in closeWindow
    self.winList.remove(win)
ValueError: list.remove(x): x not in list

On the forum I found references to base.closeWindow only in the context of quitting the game cleanly.

Am I perhaps doing something conceptually wrong here? I wanted to have a render-to-texture created whenever a certain effect is triggered, and destroyed when the effect is done. There may be zero, one or several of these effects running at any given moment.

4

Sorry, the correct line is this:

base.graphicsEngine.removeWindow(mybuffer)

You can find examples of temporary render-to-texture set-ups in direct/(src/)showbase/ShowBase.py, for instance in the method saveCubeMap.

5

That works, thanks.

On the other hand… I’ve now tried this in one case where so far I reused one and the same buffer, and after a number of creations/destructions, the frame rate starts to drop off. While when I try it in a standalone toy case, creations/destructions go on indefinitely without any drop in frame rate. Is it possible that the buffer does not get removed due to some active reference, and how could I check that (like getting a list of existing buffers)?

6

I’ve run into this issue before, too, where a buffer seems to be hanging around longer than it should. It’s possible to track it down using Python’s existing reference-count debugging tools, but it’s tedious.

It might be easier just to re-use the same buffer every time, instead of closing and reopening buffers.

David

7

This might be of interest, its a queueing based texture renderer that reuses buffers: https://github.com/Craig-Macomber/Panda3D-Terrain-System/blob/master/textureRenderer.py

I’ve used it to render thousands of textures in a run, so I’m pretty sure it doesn’t leak, though I haven’t stress tested it recently.