TSL: Inconsistent chaining for `step` vs `smoothstep`

[boytchev]

Description

The chaining of step and smoothstep are inconsistent with each other. smoothstep chains the last parameter, which is OK, but steps chains the first parameter - this is inconsistent with smoothstep, but consistent with most other chaining, where the first parameter got chained.

• smoothstep( e0, e1, x ) → x.smoothstep( e0, e1 ) -- this is OK
• step( edge, x ) → edge.step( x ) -- this is inconsistent

Two suggestions:

• Making step consistent with smoothstep and chain its last parameter x.step( edge )
• Adding documentation about what parameter is chained, e.g. always the fisrt, except for step, smoothstep...

Issues:

• Such change will break already existing TSL-based code

Reproduction steps

1. Place the code form [Code] section in the TSL Editor
2. Uncomment one of the lines 5..9 to see the effect
3. Lines 5, 6 and 7 work fine
4. Line 8 should result as 7, but it is not
5. Line 9 just tests that step chains the first parameter

Code

const { float, vec4, uv, step, smoothstep } = await import( 'three/tsl' );

const x = uv().x;

//const r = smoothstep( 0.25, 0.75, x );
//const r = x.smoothstep( 0.25, 0.75 );
//const r = step( 0.5, x );
const r = x.step( 0.5 );
//const r = float( 0.5 ).step( x );

output = vec4( r, 0, 0, 1 );

Live example

(not provided)

Screenshots

Left two snapshots show that smoothstep chains the last parameter.
Right three snapshots show that step chains the first parameter.

Version

r176

Device

Desktop

Browser

Chrome

OS

Windows