Add lerp to Math

[DartBot]

This issue was originally filed by [email protected]

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Implementation something like

double lerp(double t, num min, num max) {
  return min + t * (max - min);
}

[DartBot]

This comment was originally written by [email protected]

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Removed Type-Defect label.
Added Type-Enhancement, Area-Library, Triaged labels.

[DartBot]

This comment was originally written by [email protected]

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i'm not sure what the libraries stance on validation is, but this method might want to:

assert(t >= 0 && t <= 1);

[DartBot]

This comment was originally written by [email protected]

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I'd prefer something more webgl glsl'y. So mix instead of lerp?

num mix(num min, num max, double a)
{
   return min + a * (max - min);
}

Float32x4 mix(Float32x4 min, Float32x4 max, double a)
{
   return min + (max - min).scale(a);
}

Maybe a few others?

double smoothstep(num edge0, num edge1, double val)
{
   double t = ((val - edge0) / (edge1 - edge0)).clamp(0.0, 1.0);
   return t * t * (3.0 - 2.0 * t);
}

Float32x4 smoothstep(Float32x4 edge0, Float32x4 edge1, double val)
{
   Float32x4 t = ((new Float32x4(val,val,val,val) - edge0) / (edge1 - edge0))
     .clamp(new Float32x4.zero(), new Float32x4(1.0,1.0,1.0,1.0);
   return t * t * (Float32x4(3.0,3.0,3.0,3.0) - t.scale(2.0));
}

not necessarily sure these should be in math as clamp and mod live on the datatypes Float32x4 and num (though there is no mod on Float32x4)

[floitschG]

I think these fit better in a WebGl package. Potentially with other 3D primitives (like tools to work with Quaternions, ...).

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Added NotPlanned label.