Realtime Lights and Shadows on Mobile

Hi, I was wondering if there is any way to approach realtime shadows on mobile that could give me anywhere near 30 fps.

It seems like if I have any realtime lights that are capable of casting a shadow, the fps drops to 22 or lower. Immediately. No matter how much I try to cut down on the objects that are capable of casting or receiving these shadows, the framerate barely changes.

I realize my Android phone isn't the greatest, and expecting strong performance from it might be unreasonable, but it's frustrating to keep throwing effort at this and hoping I can work my way up to 30 fps. In reality, a plane with a stationary cube throwing a realtime shadow is a large framerate hit right away, and just having two characters onscreen pushes down to 20fps.

Is this just how things are, or is there a solution? It seems I ought to just give up on any sort of mobile game with realtime shadows.

 

What is your phone?

What shaders are you using?

 

My phone is a Moto G, the shaders are the unity standard shader on everything.

 

Don't use the standard shader.

 

I have the same issue. Even when only one object drops shadow, the drawcall of the entire scene is doubled. It seems screen space shadow is turned on by default. As I can remember things didn't work like that several versions ago.

 

I have one directional light and about 50 shadow casters in my mobile game as the video below shows - skip to about 25 seconds when the game has actually started:

I never get less the 45fps - which is the target fps.

So how does this work?

• Do not use the standard shader. Use the mobile shaders.
• Turn off all GI
• Have a very small shadow distance. If you look you will see the shadows pop up a bit in the video
• You can have soft shadows but no shadow cascades.
• One directional light only

 

I would add that keeping screen space shadows should actually help performance, as it greatly reduces the cost to lookup a shadow value for all the geometry. Basically a tex2D lookup with uv versus having to sample the directional cascaded shadowmap which requires a lot of matrix multiplications.

Unless I am missing something... someone correct me if I am wrong

 

What are "screen space shadows"? Thanks.

 

Directional light shadows are usually computed by rendering the scene depth to what is called a cascade map. This can have 1, 2 or 4 quadrants depending on quality settings. A shadow value for any world space position and distance from the camera can then be computed, but this requires some matrix math to get the world position turned into a "shadow" position. With screen space shadows, the cascade shadow map can be transformed into a full screen texture with a lot of softening and other filtering applied, and finally any shader that needs shadows can simply do a texture lookup using the full screen uv coordinate to do shadow light computation.

 

Thanks for this info!

 

Is this an asset I would purchase or something within Unity? Thanks.

 

No look in your quality settings and down there will be shadow Cascades