code: function( r, g, b, a ){
      this._dat[ 0|BLEND_COLOR_R ] = encodeHalf( r );
      this._dat[ 0|BLEND_COLOR_G ] = encodeHalf( g );
      this._dat[ 0|BLEND_COLOR_B ] = encodeHalf( b );
      this._dat[ 0|BLEND_COLOR_A ] = encodeHalf( a );
      this._set |= BLEND_COLOR_SET|0;
      return this;
    }
docs: /*
  blendColor
  r g b a  as Float [0.0, 1.0]