Add AdjustmentFilter

[finscn]

This filter could help use to Adjust some basic properties of color :
gamma, contrast, saturation, brightness, alpha & RGB Channel.

Some effects also could be done with ColorMatrixFilter ,
But AdjustmentFilter is simple & easy to be understood .

And It's more fast than ColorMatrixFilter. The core of the shader :

    vec3 rgb = pow(c.rgb, vec3(1. / gamma));
    rgb = mix(vec3(.5), mix(vec3(dot(vec3(.2125, .7154, .0721), rgb)), rgb, saturation), contrast);
    rgb.r *= red;
    rgb.g *= green;
    rgb.b *= blue;
    c.rgb = rgb * brightness;

There is no any complicated matrix computation .

Online example: http://fatidol.com/pixi-filters/

[bigtimebuddy]

Change copyright?

[finscn]

After all of my filters be merged , I will create a new PR for change all of them.

[bigtimebuddy]

Okay 👍

[bigtimebuddy]

Need to documentation for each of the properties, not just the constructor options.

[finscn]

I don't understand.... How to add documentation in Object.assign() ?

[bigtimebuddy]

I'm not sure if you need to add the name after @member or not if it's not attached to this.gamma. Test the documentation with npm run docs to preview.

Object.assign(this, {
  /**
   * The amount of Gamma
   * @member {number} gamma
   * @default 1
   */
  gamma: 1,

[finscn]

can't run npm run docs I don't know why...

[bigtimebuddy]

Another awesome and useful filter. Thanks @finscn!