@openhps/core/dist/esm/three/nodes/display/BumpMapNode.js

Open Hybrid Positioning System - Core component

import TempNode from '../core/TempNode.js';
import { uv } from '../accessors/UV.js';
import { normalView } from '../accessors/Normal.js';
import { positionView } from '../accessors/Position.js';
import { faceDirection } from './FrontFacingNode.js';
import { Fn, nodeProxy, float, vec2 } from '../tsl/TSLBase.js';

// Bump Mapping Unparametrized Surfaces on the GPU by Morten S. Mikkelsen
// https://mmikk.github.io/papers3d/mm_sfgrad_bump.pdf

const dHdxy_fwd = Fn(({
  textureNode,
  bumpScale
}) => {
  // It's used to preserve the same TextureNode instance
  const sampleTexture = callback => textureNode.cache().context({
    getUV: texNode => callback(texNode.uvNode || uv()),
    forceUVContext: true
  });
  const Hll = float(sampleTexture(uvNode => uvNode));
  return vec2(float(sampleTexture(uvNode => uvNode.add(uvNode.dFdx()))).sub(Hll), float(sampleTexture(uvNode => uvNode.add(uvNode.dFdy()))).sub(Hll)).mul(bumpScale);
});

// Evaluate the derivative of the height w.r.t. screen-space using forward differencing (listing 2)

const perturbNormalArb = Fn(inputs => {
  const {
    surf_pos,
    surf_norm,
    dHdxy
  } = inputs;

  // normalize is done to ensure that the bump map looks the same regardless of the texture's scale
  const vSigmaX = surf_pos.dFdx().normalize();
  const vSigmaY = surf_pos.dFdy().normalize();
  const vN = surf_norm; // normalized

  const R1 = vSigmaY.cross(vN);
  const R2 = vN.cross(vSigmaX);
  const fDet = vSigmaX.dot(R1).mul(faceDirection);
  const vGrad = fDet.sign().mul(dHdxy.x.mul(R1).add(dHdxy.y.mul(R2)));
  return fDet.abs().mul(surf_norm).sub(vGrad).normalize();
});

/**
 * This class can be used for applying bump maps to materials.
 *
 * ```js
 * material.normalNode = bumpMap( texture( bumpTex ) );
 * ```
 *
 * @augments TempNode
 */
class BumpMapNode extends TempNode {
  static get type() {
    return 'BumpMapNode';
  }

  /**
   * Constructs a new bump map node.
   *
   * @param {Node<float>} textureNode - Represents the bump map data.
   * @param {?Node<float>} [scaleNode=null] - Controls the intensity of the bump effect.
   */
  constructor(textureNode, scaleNode = null) {
    super('vec3');

    /**
     * Represents the bump map data.
     *
     * @type {Node<float>}
     */
    this.textureNode = textureNode;

    /**
     * Controls the intensity of the bump effect.
     *
     * @type {?Node<float>}
     * @default null
     */
    this.scaleNode = scaleNode;
  }
  setup() {
    const bumpScale = this.scaleNode !== null ? this.scaleNode : 1;
    const dHdxy = dHdxy_fwd({
      textureNode: this.textureNode,
      bumpScale
    });
    return perturbNormalArb({
      surf_pos: positionView,
      surf_norm: normalView,
      dHdxy
    });
  }
}
export default BumpMapNode;

/**
 * TSL function for creating a bump map node.
 *
 * @tsl
 * @function
 * @param {Node<float>} textureNode - Represents the bump map data.
 * @param {?Node<float>} [scaleNode=null] - Controls the intensity of the bump effect.
 * @returns {BumpMapNode}
 */
export const bumpMap = /*@__PURE__*/nodeProxy(BumpMapNode).setParameterLength(1, 2);