ngraph.leiden/demo/gl/SimpleLineCollection.js

Leiden/Louvain community detection for ngraph.graph (JS)

import { GLCollection, defineProgram, ColorAttribute, InstancedAttribute } from 'w-gl';

export default class SimpleLineCollection extends GLCollection {
  constructor(gl, options = {}) {
    const program = defineProgram({
      gl,
      vertex: `
        uniform mat4 modelViewProjection;
        uniform float width;
        uniform vec2 resolution;
        attribute vec4 color;
        attribute vec3 from, to;
        attribute vec2 point;
        varying vec4 vColor;
        void main() {
          vec4 clip0 = modelViewProjection * vec4(from, 1.0);
          vec4 clip1 = modelViewProjection * vec4(to, 1.0);
          vec2 screen0 = resolution * (0.5 * clip0.xy/clip0.w + 0.5);
          vec2 screen1 = resolution * (0.5 * clip1.xy/clip1.w + 0.5);
          vec2 xBasis = normalize(screen1 - screen0);
          vec2 yBasis = vec2(-xBasis.y, xBasis.x);
          vec2 pt0 = screen0 + width * point.x * yBasis;
          vec2 pt1 = screen1 + width * point.x * yBasis;
          vec2 pt = mix(pt0, pt1, point.y);
          vec4 clip = mix(clip0, clip1, point.y);
          gl_Position = vec4(clip.w * (2.0 * pt/resolution - 1.0), clip.z, clip.w);
          vColor = color.abgr;
        }
      `,
      fragment: `
        precision highp float;
        varying vec4 vColor;
        void main() { gl_FragColor = vColor; }
      `,
      attributes: { color: new ColorAttribute() },
      instanced: { point: new InstancedAttribute([ -0.5, 0, -0.5, 1, 0.5, 1, -0.5, 0, 0.5, 1, 0.5, 0 ]) }
    });
    super(program);
    this.width = options.width || 2;
  }
  draw(_, drawContext) {
    if (!this.uniforms) {
      this.uniforms = { modelViewProjection: this.modelViewProjection, width: this.width, resolution: [drawContext.width, drawContext.height] };
    }
    this.uniforms.resolution[0] = drawContext.width;
    this.uniforms.resolution[1] = drawContext.height;
    this.program.draw(this.uniforms);
  }
}