The function ApplyHue in Packages/com.vrchat.base/Runtime/VRCSDK/Sample Assets/Shaders/Mobile/ToonStandard/CG/Helpers.cginc

can be replaced by the following function, yielding 1:1 results.

// Rotates white-point to Z axis, rotates around Z, undo white-point rotation.

half3 ApplyHue(half3 col, half hueAngle, half mask)

{

UNITY_BRANCH

if (hueAngle == 0)

{

return col;

}

else

{

const half PI = 3.14159265359;

const half3 OFFSETS = PI * half3(0.0/3.0, 2.0/3.0, 4.0/3.0);

half3 ct = (1.0/3.0) + (2.0/3.0) * cos(hueAngle + OFFSETS);

half3 shifted = (col.rgb ct.y) + (col.brg * ct.z);

return lerp(col, shifted, mask);

}

}

In my testing, the original ApplyHue function compiles to this:

0: sample r0.xyzw, v1.xyxx, t0.xyzw, s0

1: eq r0.w, cb0[2].x, l(0.000000)

2: if_nz r0.w

3: mov o0.xyz, r0.xyzx

4: else

5: sincos r1.x, r2.x, cb0[2].x

6: mul r1.yzw, r0.zzxy, l(0.000000, 0.577350, 0.577350, 0.577350)

7: mad r1.yzw, r0.zzxy, l(0.000000, 0.577350, 0.577350, 0.577350), -r1.wwyz

8: mul r1.xyz, r1.xxxx, r1.yzwy

9: mad r1.xyz, r0.xyzx, r2.xxxx, r1.xyzx

10: dp3 r0.w, l(0.577350, 0.577350, 0.577350, 0.000000), r0.xyzx

11: mul r0.w, r0.w, l(0.577350)

12: add r1.w, -r2.x, l(1.000000)

13: mad r1.xyz, r0.wwww, r1.wwww, r1.xyzx

14: add r1.xyz, -r0.xyzx, r1.xyzx

15: mad o0.xyz, v1.zzzz, r1.xyzx, r0.xyzx

16: endif

17: ret

while my function this compiles to this:

0: sample r0.xyzw, v1.xyxx, t0.xyzw, s0

1: eq r0.w, cb0[2].x, l(0.000000)

2: if_nz r0.w

3: mov o0.xyz, r0.xyzx

4: else

5: add r1.xyz, cb0[2].xxxx, l(0.000000, 2.094395, 4.188790, 0.000000)

6: sincos null, r1.xyz, r1.xyzx

7: mad r1.xyz, r1.xyzx, l(0.666667, 0.666667, 0.666667, 0.000000), l(0.333333, 0.333333, 0.333333, 0.000000)

8: mul r2.xyz, r0.yzxy, r1.yyyy

9: mad r1.xyw, r0.xyxz, r1.xxxx, r2.xyxz

10: mad r1.xyz, r0.zxyz, r1.zzzz, r1.xywx

11: add r1.xyz, -r0.xyzx, r1.xyzx

12: mad o0.xyz, v1.zzzz, r1.xyzx, r0.xyzx

13: endif

14: ret

Both functions use two temporary registers when I tested them in fragment.

Optionally

half3 ct = (1.0/3.0) + (2.0/3.0) * cos(hueAngle + OFFSETS);

can be replaced with

half3 ct = (1.0/3.0) + (2.0/3.0) UNITY_TWO_PI + OFFSETS);

to resolve feedback like this one

I have made supplemental demos in Desmos to showcase the methods:

I hereby grant legal rights to all shader code presented in this feature request. I present all of the above, granting full rights to use, reuse, modify, redistribute, and will not persue any form of legal action, following the guidelines of the MIT-0 No Attribution licence. blablabla open source, use it as you wish!

ApplyHueMinimal.shader (which I have renamed to .txt for sending) has the MIT-0 licence as a header segment by the way.