What are the guidelines regarding decal usage as regards performance?
Can I have thousands of these things at one time?.. Am I correct in assuming decals get culled if occluded?
For example, a city scene with many walls with different decal graffiti…is this a reasonable use of decals?
Decals cost mostly in overdraw, similar to unshadowed dynamic lights or if you placed translucent sheets everywhere. The best test is to setup a representative scene of what you want to make and then profile on your target hardware. ‘profilegpu’ will show you GPU timings.