Materials: Consider to use mediump for all shaders

Description of the problem

Right now, the default precision for shader progams in three.js is highp. Issues like #14137 showed that this approach causes rendering problems especially on (older) mobile devices . Using mediump would solve these issues and also improve the performance of the shader execution on mobile, see https://github.com/mrdoob/three.js/issues/14137#issuecomment-397850032.

The problem is that certain materials like MeshStandardMaterial can not produce correct visual output with mediump right now, see https://github.com/mrdoob/three.js/issues/14137#issuecomment-397856954. Changing certain parts of the shader souce code is necessary to solve this issue.

Three.js version

• Dev
• r94
• …

Browser

• All of them
• Chrome
• Firefox
• Internet Explorer

OS

• All of them
• Windows
• macOS
• Linux
• Android
• iOS

Hardware Requirements (graphics card, VR Device, …)

[mrdoob]

I’m thinking this is something that is not that relevant/needed nowadays…

[Supernuija]

I think the option to set mediump by default and update all the required shader code so the lighting doesn’t break (#14570 (comment)) by @mrdoob was a good idea.

Unfortunately I am not experienced enough to do that, but I hope someone who knows the area better finds this thread and gives it a go. I am more than willing to do the tests when needed with actual mobile hw.