Many coincident PlaneGeometry causes slow rendering performance

Questions
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1

Hi! Thanks for taking a look at this question.

I noticed that if you make a bunch ~ 20-50 of PlaneGeometries and place them near the same location, then zoom the camera in, rendering performance tanks. Example:

Open up that codepen in a new window to see what I’m talking about.

The above is a very contrived example, but demonstrates exactly what I’m talking about. Rendering performance appears to be bad when the geometries are close to the camera, or if they are large. So in a sense, it looks like the more of the viewport these geometries take up, the worse the performance. Personally, I’m getting ~30-40fps on my 2016 macbook pro when zoomed in, 60fps when zoomed out.

If I add hundreds of the geometries to the scene in different locations, the performance is good. The problem happens when the they are very close together, and when the camera is close to the geometries.

Can someone help me understand what’s going on here?

Thanks!

2

I think you’re suffering from overdraw. Three can’t figure out what’s the best way to draw them because of how they’re organized in space (looks like they’re all in the same location). I’m not sure what exactly happens, but i’ve had problems when say particles end up being drawn one over another on the entire screen due to some shader glitch.