Source: packages/filters/filter-blur/src/BlurFilterPass.js

import { Filter } from '@pixi/core';
import { settings } from '@pixi/settings';
import { generateBlurVertSource } from './generateBlurVertSource';
import { generateBlurFragSource } from './generateBlurFragSource';
import { CLEAR_MODES } from '@pixi/constants';
/**
 * The BlurFilterPass applies a horizontal or vertical Gaussian blur to an object.
 *
 * @class
 * @extends PIXI.Filter
 * @memberof PIXI.filters
 */
export class BlurFilterPass extends Filter {
    /**
     * @param {boolean} horizontal - Do pass along the x-axis (`true`) or y-axis (`false`).
     * @param {number} [strength=8] - The strength of the blur filter.
     * @param {number} [quality=4] - The quality of the blur filter.
     * @param {number} [resolution=PIXI.settings.FILTER_RESOLUTION] - The resolution of the blur filter.
     * @param {number} [kernelSize=5] - The kernelSize of the blur filter.Options: 5, 7, 9, 11, 13, 15.
     */
    constructor(horizontal, strength = 8, quality = 4, resolution = settings.FILTER_RESOLUTION, kernelSize = 5) {
        const vertSrc = generateBlurVertSource(kernelSize, horizontal);
        const fragSrc = generateBlurFragSource(kernelSize);
        super(
        // vertex shader
        vertSrc, 
        // fragment shader
        fragSrc);
        this.horizontal = horizontal;
        this.resolution = resolution;
        this._quality = 0;
        this.quality = quality;
        this.blur = strength;
    }
    /**
     * Applies the filter.
     *
     * @param {PIXI.systems.FilterSystem} filterManager - The manager.
     * @param {PIXI.RenderTexture} input - The input target.
     * @param {PIXI.RenderTexture} output - The output target.
     * @param {PIXI.CLEAR_MODES} clearMode - How to clear
     */
    apply(filterManager, input, output, clearMode) {
        if (output) {
            if (this.horizontal) {
                this.uniforms.strength = (1 / output.width) * (output.width / input.width);
            }
            else {
                this.uniforms.strength = (1 / output.height) * (output.height / input.height);
            }
        }
        else {
            if (this.horizontal) // eslint-disable-line
             {
                this.uniforms.strength = (1 / filterManager.renderer.width) * (filterManager.renderer.width / input.width);
            }
            else {
                this.uniforms.strength = (1 / filterManager.renderer.height) * (filterManager.renderer.height / input.height); // eslint-disable-line
            }
        }
        // screen space!
        this.uniforms.strength *= this.strength;
        this.uniforms.strength /= this.passes;
        if (this.passes === 1) {
            filterManager.applyFilter(this, input, output, clearMode);
        }
        else {
            const renderTarget = filterManager.getFilterTexture();
            const renderer = filterManager.renderer;
            let flip = input;
            let flop = renderTarget;
            this.state.blend = false;
            filterManager.applyFilter(this, flip, flop, CLEAR_MODES.CLEAR);
            for (let i = 1; i < this.passes - 1; i++) {
                filterManager.bindAndClear(flip, CLEAR_MODES.BLIT);
                this.uniforms.uSampler = flop;
                const temp = flop;
                flop = flip;
                flip = temp;
                renderer.shader.bind(this);
                renderer.geometry.draw(5);
            }
            this.state.blend = true;
            filterManager.applyFilter(this, flop, output, clearMode);
            filterManager.returnFilterTexture(renderTarget);
        }
    }
    /**
     * Sets the strength of both the blur.
     *
     * @member {number}
     * @default 16
     */
    get blur() {
        return this.strength;
    }
    set blur(value) {
        this.padding = 1 + (Math.abs(value) * 2);
        this.strength = value;
    }
    /**
     * Sets the quality of the blur by modifying the number of passes. More passes means higher
     * quaility bluring but the lower the performance.
     *
     * @member {number}
     * @default 4
     */
    get quality() {
        return this._quality;
    }
    set quality(value) {
        this._quality = value;
        this.passes = value;
    }
}