@openhps/core/dist/esm/three/nodes/fog/Fog.js

Open Hybrid Positioning System - Core component

import { positionView } from '../accessors/Position.js';
import { smoothstep } from '../math/MathNode.js';
import { Fn, output, vec4 } from '../tsl/TSLBase.js';

/**
 * Returns a node that represents the `z` coordinate in view space
 * for the current fragment. It's a different representation of the
 * default depth value.
 *
 * This value can be part of a computation that defines how the fog
 * density increases when moving away from the camera.
 *
 * @param {NodeBuilder} builder - The current node builder.
 * @return {Node} The viewZ node.
 */
function getViewZNode(builder) {
  let viewZ;
  const getViewZ = builder.context.getViewZ;
  if (getViewZ !== undefined) {
    viewZ = getViewZ(this);
  }
  return (viewZ || positionView.z).negate();
}

/**
 * Constructs a new range factor node.
 *
 * @tsl
 * @function
 * @param {Node} near - Defines the near value.
 * @param {Node} far - Defines the far value.
 */
export const rangeFogFactor = Fn(([near, far], builder) => {
  const viewZ = getViewZNode(builder);
  return smoothstep(near, far, viewZ);
});

/**
 * Represents an exponential squared fog. This type of fog gives
 * a clear view near the camera and a faster than exponentially
 * densening fog farther from the camera.
 *
 * @tsl
 * @function
 * @param {Node} density - Defines the fog density.
 */
export const densityFogFactor = Fn(([density], builder) => {
  const viewZ = getViewZNode(builder);
  return density.mul(density, viewZ, viewZ).negate().exp().oneMinus();
});

/**
 * This class can be used to configure a fog for the scene.
 * Nodes of this type are assigned to `Scene.fogNode`.
 *
 * @tsl
 * @function
 * @param {Node} color - Defines the color of the fog.
 * @param {Node} factor - Defines how the fog is factored in the scene.
 */
export const fog = Fn(([color, factor]) => {
  return vec4(factor.toFloat().mix(output.rgb, color.toVec3()), output.a);
});

// Deprecated

/**
 * @tsl
 * @function
 * @deprecated since r171. Use `fog( color, rangeFogFactor( near, far ) )` instead.
 *
 * @param {Node} color
 * @param {Node} near
 * @param {Node} far
 * @returns {Function}
 */
export function rangeFog(color, near, far) {
  // @deprecated, r171

  console.warn('THREE.TSL: "rangeFog( color, near, far )" is deprecated. Use "fog( color, rangeFogFactor( near, far ) )" instead.');
  return fog(color, rangeFogFactor(near, far));
}

/**
 * @tsl
 * @function
 * @deprecated since r171. Use `fog( color, densityFogFactor( density ) )` instead.
 *
 * @param {Node} color
 * @param {Node} density
 * @returns {Function}
 */
export function densityFog(color, density) {
  // @deprecated, r171

  console.warn('THREE.TSL: "densityFog( color, density )" is deprecated. Use "fog( color, densityFogFactor( density ) )" instead.');
  return fog(color, densityFogFactor(density));
}