P3D v3 Missing Tree Polygons


Resource contributor
I can confirm that this issue does not occur in FSX. Have not tested P3D 1 or 2.

TLDR; Either the horizontal polygons (canopy) or vertical polygons (side view) of my tree models appear, but never both.

I started attempting to create fuller autogen tree models; cross trees aren't as voluminous as I would like. However P3D doesn't seem to like my new non-cross trees.

This is an example model in MCX, all polys visible.

This is the autogen in P3D3, only canopy visible.
bush top.jpg

Exact same autogen call, a few hundred feet away, only the sides visible.
bush side.jpg

I have tested and ruled out the following: empty portion of texture sheet in use; incorrect autogen call.

I thought it might be a draw call issue, but I doubt, as all my autogen currently in the scene only use 2 texture sheets (1 for the trees themselves and 1 for the canopies). I also thought it might be too many texture vertices for the 2 draw calls, but even when I remove all other models and leave just one autogen model in the scene, polygons still disappear. Also, FSX displays all the polys just fine.

Has anybody experienced this issue? Any ideas? Is it a problem with my model? Find sample library, texture sheets and autogen xml attached
for testing. (Autogen Configuration Merger will be needed, then you can simply drop the descriptions on any test scenery).
I'd appreciate any ideas.




Resource contributor
Update: so I went in and turned off drawcall batching on my models as a test, and half the polys came back. I'm stumped.


Staff member
FSDevConf team
Resource contributor
That might indicate there are too many polygons for the drawcall batching. I have seen that before with more complex models. Still weird that it doesn't happen in FSX though.


Resource contributor
I did more testing using a simpler model. 2 vertical planes for the tree, 1 horizontal plane for the canopy, 27 triangles in total, 39 texture verts, 2 draw calls.
Within P3D it was the ONLY tree in the scenery, and extremely sparsely spaced.
Only the horzontal planes showed up.

I went in and started playing with material settings; first, I changed the Alpha Test Level from 128 down to 4. This caused the horizontal canopy plane to show up, but the vertical tree planes disappeared.
I adjusted other settings like Vertical Normals and Z write Alpha but those made no difference.
Sooo (here's the intersting part) I went and put the Alpha test level back to 128 and... the vertical tree planes didn't come back.

The behaviour of these models in P3D seems ENTIRELY random.


Resource contributor
Ive done everything I can think off, optimized the model and used double sided materials to reduce the triangle count down to 6. Copied the material values from the default autogen exactly (minus the fresnel map). I still cant get all the polys to appear. Can anyone test it out for me please?



Resource contributor
I'm assuming that no one could reproduce my missing polygons?

UPDATE: I managed to get all the polygons back on one model by using one large texture sheet instead of 2 separate ones. I have no idea why this works.
I did not want to decrease the quality of the images so the sheet is now 2048px instead of 1024. I will observe how this affects performance as I now plan to fit all my vegetation onto one sheet.
Hopefully nothing breaks again.