Many material slots = Many drawcalls = Low FPS?
I have a model with many material slots from 3DS Max. In total, there are 127 materials applied. I broke this down to several meshes so I don't hit the limit of 64 materials in UE4.
The triangle count is about 700.000 for all the meshes combined (it's a extremely detailed car, complete with interior, engine etc.)
As you might guess, the performance isn't that great now, the combined model with all materials needs about 180 drawcalls.
But I am not sure, what's actually the main problem here:
Does it make a difference to combine the materials in 3DS (which is hell) or is it ok to just use the same material on many slots?
Is there a way to reliable find the bottleneck for a scene? The GPU profiler results differ greatly from frame to frame.
Many thanks, spyro
Every material after the first adds another drawcall, so yes that would be at least 180 drawcalls. It means that the entire mesh needs to be drawn at least 180 times before the next frame, which will result in being a giant bottleneck.
It makes a huge difference to combine the materials in 3dsmax, if you'd manage to combine them all that would be one drawcall, though depending on the detail you need you could combine all the materials in a few materials. I cant guess what you need it for, but you could seperate the mesh per grouped material and combine them in a blueprint so not the entire car needs to be redrawn for each material it has.
The polycount isnt your biggest issue, but for games it is on the high side.. that said if its a racing game with only a few cars in sight with good LOD-ing it shouldnt be the biggest issue. Cant give detailed info on the lighting though.
I know it sucks, but I suggest to massively reduce the amount of materials you need.
answered May 05 '15 at 08:16 PM
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