separates light entities shaders from light maps shaders

[sunag]

It is a continuation of #13149

This PR is just a division of the lights shaders in multiples files not affecting in anything the rendering since it is including.
The main cause is to be able to use native properties names like .envMap together with lights shaders and modify values of irradiance, radiance and clearCoatRadiance not need duplicate calculations.

The core modification its about:

---

lights_pars is separate to:

• lights_pars -> light entities shaders
• lights_maps_pars -> light maps (USE_ENVMAP)

---

lights_template is separate to:

• begin_lights_fragment -> light entities begin
• lights_maps_fragment -> light maps (USE_LIGHTMAP, USE_ENVMAP)
• end_lights_fragment -> light entities end

---

If add the ShaderChunk in sequence we will have the same result from the previous code, for example:

legacy.lights_pars = lights_pars + lights_maps_pars;
legacy.lights_template = begin_lights_fragment + lights_maps_fragment + end_lights_fragment;

/cc @WestLangley @bhouston

[WestLangley]

OK. I would suggest you not reuse the lights_pars.glsl filename. Remove it. I am concerned this will cause problems for users who are using existing shader chunks in their code.

I suggest the following name changes:

legacy.lights_pars = begin_lights_pars + maps_lights_pars;
legacy.lights_template = begin_lights_fragment + maps_light_fragment + end_lights_fragment;

[sunag]

@WestLangley Ok! Done.

[mrdoob]

I think lights_fragment_begin, lights_fragment_maps and lights_fragment_end reads better.

[WestLangley]

I think lights_fragment_begin, lights_fragment_maps and end_lights_fragment_end reads better.

OK.

Then, for consistency, lights_pars_begin and lights_pars_maps ?

[mrdoob]

Yep!

[sunag]

Renamed!

[WestLangley]

lights_pars_begin

[sunag]

Fixed 👍

[mrdoob]

I think you forgot to remove lights_template.glsl?

[sunag]

Removed!

[mrdoob]

Thanks!

[WestLangley]

Reminder to note in migration:

lights_pars.glsl -> lights_pars_begin.glsl + lights_pars_maps.glsl
lights_template.glsl -> lights_fragment_begin.glsl + lights_fragment_maps.glsl + lights_fragment_end.glsl

[mrdoob]

Reminder to note in migration:

lights_pars.glsl -> lights_pars_begin.glsl + lights_pars_maps.glsl
lights_template.glsl -> lights_fragment_begin.glsl + lights_fragment_maps.glsl + lights_fragment_end.glsl

Done. Thanks!