/**
 * LineDashedShaderMaterial
 *
 * @author rabbib76, realor
 */

import * as THREE from '../lib/three.module.js'

class LineDashedShaderMaterial extends THREE.ShaderMaterial {
    static VERTEX_SHADER = `
flat out vec3 startPos;
out vec3 vertPos;

void main()
{
  vec4 pos    = projectionMatrix * modelViewMatrix * vec4(position, 1.0);
  gl_Position = pos;
  vertPos     = pos.xyz / pos.w;
  startPos    = vertPos;
}
`
    static FRAGMENT_SHADER = `
precision highp float;

flat in vec3 startPos;
in vec3 vertPos;

uniform vec3  u_color;
uniform vec2  u_resolution;
uniform float u_dashSize;
uniform float u_gapSize;

void main()
{
  vec2 dir   = (vertPos.xy - startPos.xy) * u_resolution / 2.0;
  float dist = length(dir);
  float dashGapSize = u_dashSize + u_gapSize;

  if (fract(dist / dashGapSize) > u_dashSize / dashGapSize)
    discard;
  gl_FragColor = vec4(u_color.rgb, 1.0);
}
`
    constructor(options = {}) {
        const color = options.color || new THREE.Color(0, 0, 0)
        const dashSize = options.dashSize || 4
        const gapSize = options.gapSize || 4

        const uniforms = {
            u_color: { type: 'v3', value: { x: color.r, y: color.g, z: color.b } },
            u_resolution: { type: 'v2', value: { x: 1600, y: 1000 } },
            u_dashSize: { type: 'f', value: dashSize },
            u_gapSize: { type: 'f', value: gapSize }
        }

        super({
            uniforms: uniforms,
            vertexShader: LineDashedShaderMaterial.VERTEX_SHADER,
            fragmentShader: LineDashedShaderMaterial.FRAGMENT_SHADER,
            depthTest: options.depthTest === undefined ? true : options.depthTest,
            depthWrite: options.depthWrite === undefined ? true : options.depthWrite
        })
    }
}

export { LineDashedShaderMaterial }