Customising Shaders

Currently we can set material.vert and material.frag but that breaks as we also include them in the depth prepass shaders vert: material.vert || DEPTH_PASS_VERT. The correct (needs testing) way is to define all 3 shaders and use preprocessor to support all 3 cases

#ifdef DEPTH_PRE_PASS_ONLY
//copy pre pass shader
#elseif DEPTH_PASS_ONLY
//copy depth shader
#else
//pbr shader
#endif

That’s painful.

Related

• ThreeJS discussion about string replacement before compile https://github.com/mrdoob/three.js/issues/11475
• Use Shader Modifiers to Extend SceneKit Shading

[vorg]

TLDR: not aiming for fully dynamic gpu compute graphs, just avoiding yet-another-pbr-version-with-this-one-small-change

To answer concern about hooks

naming things is hard, no way I’ll remember these names without checking docs how do we choose where to insert them, do we add one hook after each function/stage?

We could limit it to those touch points VERT_BEFORE_TRANSFORM //after reading from attributes like aNormal VERT_AFTER_TRANSFORM //after skinning skinning, moving to world space etc FRAG_BEFORE_TEXTURES //after reading from varyings and uniforms but before reading from textures FRAG_BEFORE_PBR //before doing lighting math FRAG_AFTER_PBR //after pbr math, allows for individual direct/indirect/emissive overwrites FRAG_END //before writing to screen

What would probably cover 90% of cases for me.

how would they be injected? Shaders are strings so we’d need to clutter shaders with comment/pragma/include/custom syntax #include AFTER_DECLARATIONS + regex replace

Just few. See above

make shaders source function where we pass hooks as options?

No need. Entry points should be limited.

doesn’t allow to modify existing parts of a material

Not desired IMO. Any example use cases?

reliance on vert/frag to have these hooks

To be available only in standard PBR material.

[pailhead]

I don’t understand the idea of compiling shader graphs on the web. It seems that three’s NodeMaterial is struggling with just that. I really like the scene kit approach to this problem. I think that after you’ve made some graph, in some application, you should generate some GLSL, in three’s case something compatible with it (specific uniform/attribute names and such).

Heh i also didn’t realize i wasn’t on three’s page anymore 😄