Behavior change in r180: TSL Fn with struct params loses field access inside function body (emits 0.0); r179 works

[novogrammer]

Description

Observed (r180)

Console warning:

THREE.TSL: Member "f" does not exist in struct.

Inside addFunction, struct member access is replaced with zeros:

// r180, inside addFunction (compute WGSL excerpt)
nodeVar0 = S( ( 0.0 + 0.0 ) );

In main, accessing the returned struct’s field is emitted correctly:

// r180, in main
sc = addFunction( sa, sb );
result = vec4<f32>( sc.f );

Same result when using the render path (material.colorNode + renderer.debug.getShaderAsync).

Expected (r179)

Member access is preserved in addFunction:

// r179, inside addFunction (compute WGSL excerpt)
nodeVar0 = S( f32( ( sa.f + sb.f ) ) );

Reproduction steps

1. Define a user struct in TSL: const S=struct({f:'float'},"S");.
2. Define a TSL Fn that accepts S parameters and returns S.
3. Invoke that function from another TSL Fn.
4. Generate the shader (compute or render) and inspect the generated source and console output.

Code

import * as THREE from "three/webgpu";
import {vec4,Fn,struct,float} from 'three/tsl'

const USE_RENDER_PIPELINE=false;

function log(message){
  document.querySelector(".log").append(message+"\n");
  console.log(message);
}

async function mainAsync(){
  const scene = new THREE.Scene();
  
  const camera = new THREE.PerspectiveCamera( 75, window.innerWidth / window.innerHeight, 0.1, 1000 );
  
  const geometry = new THREE.BoxGeometry( 1, 1, 1 );
  const material = new THREE.MeshStandardNodeMaterial();
  const cube = new THREE.Mesh( geometry, material );
  scene.add( cube );
  const renderer = new THREE.WebGPURenderer({
    forceWebGL:false,
  });

  {
    const S=struct({
      f:'float',
    },"S");
    const addFunction=Fn(([sa,sb])=>{
      const result = S(sa.get("f").add(sb.get("f")));
      return result;
    }).setLayout({
      name:"addFunction",
      type:"S",
      inputs:[
        {
          name:"sa",
          type:"S",
        },
        {
          name:"sb",
          type:"S",
        },
      ],
    });
    const fooFunction=Fn(([a,b])=>{
      const sa=S(a).toVar("sa");
      const sb=S(b).toVar("sb");
      const sc=addFunction(sa,sb).toVar("sc");
      const result = vec4(sc.get("f")).toVar("result");
      return result;
    });
    
    if(USE_RENDER_PIPELINE){
      material.colorNode=fooFunction(0.2,0.8);
      const rawShader = await renderer.debug.getShaderAsync( scene, camera, cube );
      log(rawShader.fragmentShader);
    }else{
      const computeNode=fooFunction(0.2,0.8).compute(1);
      await renderer.computeAsync(computeNode);
      log(renderer._nodes.getForCompute(computeNode).computeShader);
      
    }
  }
}

mainAsync().catch((e)=>log(e));

Live example

• https://codepen.io/novogrammer/pen/pvjqVRZ?editors=0010

Screenshots

No response

Version

r180

Device

Desktop

Browser

Chrome

OS

MacOS