var core = require('../../core');
var fs = require('fs');

/**
 * This filter applies a twist effect making display objects appear twisted in the given direction.
 *
 * @class
 * @extends AbstractFilter
 * @memberof PIXI.filters
 */
function TwistFilter()
{
    core.AbstractFilter.call(this,
        // vertex shader
        null,
        // fragment shader
        fs.readFileSync(__dirname + '/twist.frag', 'utf8'),
        // custom uniforms
        {
            radius:     { type: '1f', value: 0.5 },
            angle:      { type: '1f', value: 5 },
            offset:     { type: 'v2', value: { x: 0.5, y: 0.5 } }
        }
    );
}

TwistFilter.prototype = Object.create(core.AbstractFilter.prototype);
TwistFilter.prototype.constructor = TwistFilter;
module.exports = TwistFilter;

Object.defineProperties(TwistFilter.prototype, {
    /**
     * This point describes the the offset of the twist.
     *
     * @member {Point}
     * @memberof TwistFilter#
     */
    offset: {
        get: function ()
        {
            return this.uniforms.offset.value;
        },
        set: function (value)
        {
            this.uniforms.offset.value = value;
        }
    },

    /**
     * This radius of the twist.
     *
     * @member {number}
     * @memberof TwistFilter#
     */
    radius: {
        get: function ()
        {
            return this.uniforms.radius.value;
        },
        set: function (value)
        {
            this.uniforms.radius.value = value;
        }
    },

    /**
     * This angle of the twist.
     *
     * @member {number}
     * @memberof TwistFilter#
     */
    angle: {
        get: function ()
        {
            return this.uniforms.angle.value;
        },
        set: function (value)
        {
            this.uniforms.angle.value = value;
        }
    }
});