New Feature: spotLight()

[sanketsingh24]

Nature of issue?

• New feature request

Most appropriate sub-area of p5.js?

• WebGL

New feature details:

As a part of the Summer of Code, I will be implementing spotLight() along with @aferriss in src/webgl/light.js. The function will be-
spotLight(color, position, direction, angle, concentration).

Problems-

1. The arguments angle and concentration doesn't seem to reflect what they are used for.

   • angle is the maximum dispersion of light from its direction, ie angle of the cone.
   • concentration is the attenuation of the spotLight().
     Some alternatives which we could think of-
   • angle - projection angle, opening angle, spread
   • concentration - falloff, intensity, attenuation

2. We had thought of setting angle and concentration as default to PI/3 and 1 respectively.
   But now, we have no means to distinguish between the two of them if the user sets only one of them. So we have thought that If the user wants to set the concentration, he also has to set the angle. So the usage of function would be like this-

   • spotLight(color, position, direction)
   • spotLight(color, position, direction, angle)
   • spotLight(color, position, direction, angle, concentration)

[aferriss]

Closing because this is merged in #3913