Right now, mobile is probably the most difficult platform to publish to for 3D engines. If you want to develop for mobile using 3D engines you really need to dig a little deeper and understand the basics of how a GPU works, specifically pixel/fragment shaders and vertex shaders. And you need to keep an eye on the instruction count in your materials. Many popular games use a lot of clever trickery to get good looking and low cost shaders in their games.
Once you understand how shaders run, the 3D engine you’re using becomes largely insignificant. I wrote an old article on this, just understand that fragment shaders basically run for every pixel on the screen (so if the object is larger on the screen it requires running more pixel shaders, 1 for each fragment) and vertex shaders run for every vertex. Mobile performance boils down to whether or not the GPU can process all the fragment and vertex shaders in your scene.
In all engines, Unreal especially, you need to consider:
- Vertex count of models
- Material complexity on each model
- Post Process effects
Comparing engines starts to become silly once you understand these things as what you’re really doing is comparing overall vertex + fragment shader instruction counts. Gee I wonder what the hardware will handle better, 1,000,000 instructions/frame or 200,000 instructions/frame:confused: The places people forget to look are usually Post Process effects which are basically running a fragment shader for the full 1920x1080 pixels, so having even a single one of these enabled can easily saturate your fragment shaders on fixed function pipelines.
Most of the mobile stuff I’ve worked on had fragment shaders that were max 28 instructions and that was too much for some devices only 1 year ago. So you can’t expect to grab one of these lovely 200 instruction materials and have it run with bloom, motion blur and all these fancy screen space shaders! For mobile you need to learn and use the profiling tools religiously, in many ways I think mobile is much harder to develop for than PC.