MaterialExpressionReflectionVectorWS does not function when used with a cube map on ES2 level devices (or preview mode).

Hi Guys.

Have a sphere in a scene and was trying to use the MaterialExpressionReflectionVectorWS node in a material to UV into a cubemap. This works fine on desktop, but fails on ES2 level hardware and preview mode. For reference. This is what I was doing:


Desktop result:

Mobile result:


So I did it manually like this:

and that works perfectly in ES2 preview and on device.


Hi Tommy -

I am not able to reproduce the issue that you are showing above. Both versions of the reflection vector are working as expected on ES2 Preview, Mobile Preview and deployed to an Android ES2 device (Galaxy Note 4 specifically). Perhaps it is somewhere else in your material setup, I was merely plugging the Cubemap directly into Emissive Color on a 0 Metallic and 1 Roughness Grey Material.

Let me know -

Eric Ketchum

Aha! Found the crucial step. It was working in a new project for me also until I made the material unlit and plugged in the output into the emissive. Then it fails when switched to Mobile / HTML5 preview mode or running from the device. Here is the project:

link text

Open the “CurrentMap” level and switch to “Mobile / HTML5” preview mode.

Note: Also tested on my iOS device, fails on there like in the preview when unlit, works when material is not unlit.


Hi Tommy -

Thank you for your work! That was it and I have entered a report as UE-16299. I will keep you informed as we investigate a solution to this issue.

Again, Thank You -

Eric Ketchum

Wonderful Eric! Thank you!