Using GLSL 3 ES with three.js

Three.js uses WebGL, which is available in web browsers, not GLES, which is a variant of OpenGL for mobile devices. While it is true that WebGL is itself closely related to GLES2, it is still a different thing. And currently, there only exists WebGL 1.0. Maybe future version will be more related to GLES3, but currently, no WebGL implementation will support ES 3 shaders.

Three.js is now starting to support WebGL 2.0 on the development branch. You can checkout the development version from Github.

In order to use WebGL 2.0, you can simply create a RawShaderMaterial, with your custom code, and add the #version 300 es directive at the top of your shader source.

EDIT: As of 2020 (Three.js > v113), you can directly use a ShaderMaterial and the framework already adds #version 300 es and performs other kind of conversion automatically when using WebGL2