Movable directional light works 'incorrect' on android device

[old_xia]

When using movable directional light, I got a PC ES2 preview in editor which works fine as bellow:

&d=1462778449

WHen I packaged it and download to my phone(adren 330 with android 4.4), it looks as below:

&d=1462778717

you can see in the red cycle, the dynamic light did not affect the surface, showing no light nor shadows. The interesting thing is that, when I move the camera closer, the red area(where light doesn’t reach) become smaller, when I move the camera further away from the ground, the red area become larger. It seems there is a parameter about the distance calculated from the camera’s postion to the world object’s position, which is used to decide whether dynamic light taking effect. Any Object further will have no light.
Maybe I missed some configuation about the light, or maybe It is a bug on device. I want the light cover my whole scene, any one could help?

[Arnage]

This might be a bias issue.

• Does it also happen beyond your shadow distance or does the light return there?
• Are you using cascaded shadow maps?
• Does the problem distance match the transition between two cascades?

If the answer is yes for those questions you should raise the shadow bias value of the light. (or lower the total shadow distance)

[old_xia]

hi Arnage,

@Arnage;526956

This might be a bias issue.

• Does it also happen beyond your shadow distance or does the light return there?
  I am not sure what you mean. In the scene above, the distance which distinguish the the light/unlight area, is about 10000. I got this number by moving the camera around to find the view where the shadow disapear on PC ES2 preview. The light just doesn’t show, even when the distance is less than 20000.

• Are you using cascaded shadow maps?
  Yes, and the cascaded shadow distance is set to 20000.

• Does the problem distance match the transition between two cascades?
  Do you mean whether it match the number of ‘cascaded shadow distance’ /‘number of dynamic shadow cascade’? The setting in the scene is ‘20000’/‘1’. I changed the number of dynamic shadow cascade to ‘2’ today, result is the same.

If the answer is yes for those questions you should raise the shadow bias value of the light. (or lower the total shadow distance)
Do you mean '‘Shadow Bias’ in the light color parameter group? I changed it from 0.1 to 1.0, but it did not help. I don’t know how to lower the total shadow distance.

The light settings in my scene: 1 movable directional light, 1 skylight(cast no shadow). no other light.

[old_xia]

Arnage, could u give more tips?

[Sam_Deiter]

@old xia;526843

When using movable directional light, I got a PC ES2 preview in editor which works fine as bellow:

&d=1462778449

When I packaged it and download to my phone(are 330 with android 4.4), it looks as below:

&d=1462778717

you can see in the red cycle, the dynamic light did not affect the surface, showing no light nor shadows. The interesting thing is that, when I move the camera closer, the red area(where light doesn’t reach) become smaller when I move the camera further away from the ground, the red area become larger. It seems there is a parameter about the distance calculated from the camera’s position to the world object’s position, which is used to decide whether dynamic light taking effect. Any Object further will have no light.
Maybe I missed some configuration about the light, or maybe It is a bug on the device. I want the light cover my whole scene, any one could help?

Check out the following doc page and look for the Modulated Shadows section. Dynamic shadows on mobile are expensive and do not work on all devices. Mod shadows is a much cheaper way to have dynamic shadowing on mobile devices.

Mobile Rendering Features

[old_xia]

Sam, thanks for replying. I followed the doc, changed the directional light to stationary, and checked ‘cast modulated shadow’, but the shadow didn’t showup in the PC ES2 preview(in contrast, shown in shader model 5 preview). My UE verion is 4.11.2.

about movable directional light, the area on my device does not missing only shadows, but the lighting is also missing. Is it the expected behavior?

[old_xia]

Any one knows how to make dynamic light working in mobile device? Or how to use modulate shadow with mobile?