Meshes with opacity map not properly layered/performance issues

[chg]

Thank for the help so far.

 

I think I isolated the problem more: 

 

In this demo: http://www.babylonjs-playground.com/#UB5PM#2 which is basically a plane cloned a thousand times (thousand polys sounds like a lot, but should be peanuts for a gfx card) with an alpha texture (representing the forest performance problem), I get the same bad FPS. (Increase numClones until your FPS starts to drop below acceptable)

 

Then, just decreasing the size of the plane (from 8 to 1) fixes the FPS issue for me.  Anyone else has the same experience or is it just my machine?

 

disabling hasAlpha also kind of fixes the issue. Also interesting is that changing the rotation axis from x to z (with the original size of 8) drops the FPS to 2, lol. Of course non of these changes affect draw calls, textures, mesh count, etc.

I feel your intuition about this may be wrong, without culling you have overdraw, overdraw in the order of hundreds or thousands of writes per pixel seems like a lot to me.