faceforward - return a vector pointing in the same direction as another

       Copyright © 2011-2014 Khronos Group

[FIXME: source]                                    11/18/2024                                    FACEFORWARD(3G)

genTypefaceforward(genTypeN,genTypeI,genTypeNref);genDTypefaceforward(genDTypeN,genDTypeI,genDTypeNref);

faceforward orients a vector to point away from a surface as defined by its normal. If dot()(Nref, I) < 0
       faceforward returns N, otherwise it returns -N.

       faceforward - return a vector pointing in the same direction as another

N
           Specifies the vector to orient.

       I
           Specifies the incident vector.

       Nref
           Specifies the reference vector.

reflect(), refract()

       ┌─────────────┬───────────────────────────────────────────────────────────────────────────────────┐
       │             │        OpenGLShadingLanguageVersion                                            │
       ├─────────────┼──────┬──────┬──────┬──────┬──────┬──────┬──────┬──────┬──────┬──────┬──────┬──────┤
       │ Function    │ 1.10 │ 1.20 │ 1.30 │ 1.40 │ 1.50 │ 3.30 │ 4.00 │ 4.10 │ 4.20 │ 4.30 │ 4.40 │ 4.50 │
       │ Name        │      │      │      │      │      │      │      │      │      │      │      │      │
       ├─────────────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┤
       │ faceforward │  ✔   │  ✔   │  ✔   │  ✔   │  ✔   │  ✔   │  ✔   │  ✔   │  ✔   │  ✔   │  ✔   │  ✔   │
       │ (genType)   │      │      │      │      │      │      │      │      │      │      │      │      │
       ├─────────────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┤
       │ faceforward │  -   │  -   │  -   │  -   │  -   │  -   │  ✔   │  ✔   │  ✔   │  ✔   │  ✔   │  ✔   │
       │ (genDType)  │      │      │      │      │      │      │      │      │      │      │      │      │
       └─────────────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┘