Accueil / npm / three@0.186.1 / examples / jsm / csm / CSMFrustum.js
CSMFrustum.js
import { Vector3, Matrix4 } from 'three';
const inverseProjectionMatrix = new Matrix4();
/**
* Represents the frustum of a CSM instance.
*
* @three_import import { CSMFrustum } from 'three/addons/csm/CSMFrustum.js';
*/
class CSMFrustum {
/**
* Constructs a new CSM frustum.
*
* @param {CSMFrustum~Data} [data] - The CSM data.
*/
constructor( data ) {
data = data || {};
/**
* The zNear value. This value depends on whether the CSM
* is used with WebGL or WebGPU. Both API use different
* conventions for their projection matrices.
*
* @type {number}
*/
this.zNear = data.webGL === true ? - 1 : 0;
/**
* The zFar value.
*
* @type {number}
*/
this.zFar = 1;
/**
* An object representing the vertices of the near and
* far plane in view space.
*
* @type {Object}
*/
this.vertices = {
near: [
new Vector3(),
new Vector3(),
new Vector3(),
new Vector3()
],
far: [
new Vector3(),
new Vector3(),
new Vector3(),
new Vector3()
]
};
if ( data.projectionMatrix !== undefined ) {
this.setFromProjectionMatrix( data.projectionMatrix, data.maxFar || 10000 );
}
// In case of reversed depth buffer, zNear and zFar must be 1 and 0
// respectively regardless of the coordinate system.
if ( data.reversedDepth === true ) {
this.zNear = 1;
this.zFar = 0;
}
}
/**
* Setups this CSM frustum from the given projection matrix and max far value.
*
* @param {Matrix4} projectionMatrix - The projection matrix, usually of the scene's camera.
* @param {number} maxFar - The maximum far value.
* @returns {Object} An object representing the vertices of the near and far plane in view space.
*/
setFromProjectionMatrix( projectionMatrix, maxFar ) {
const zNear = this.zNear;
const zFar = this.zFar;
const isOrthographic = projectionMatrix.elements[ 2 * 4 + 3 ] === 0;
inverseProjectionMatrix.copy( projectionMatrix ).invert();
// 3 --- 0 vertices.near/far order
// | |
// 2 --- 1
// clip space spans from [-1, 1]
this.vertices.near[ 0 ].set( 1, 1, zNear );
this.vertices.near[ 1 ].set( 1, - 1, zNear );
this.vertices.near[ 2 ].set( - 1, - 1, zNear );
this.vertices.near[ 3 ].set( - 1, 1, zNear );
this.vertices.near.forEach( function ( v ) {
v.applyMatrix4( inverseProjectionMatrix );
} );
this.vertices.far[ 0 ].set( 1, 1, zFar );
this.vertices.far[ 1 ].set( 1, - 1, zFar );
this.vertices.far[ 2 ].set( - 1, - 1, zFar );
this.vertices.far[ 3 ].set( - 1, 1, zFar );
this.vertices.far.forEach( function ( v ) {
v.applyMatrix4( inverseProjectionMatrix );
const absZ = Math.abs( v.z );
if ( isOrthographic ) {
v.z *= Math.min( maxFar / absZ, 1.0 );
} else {
v.multiplyScalar( Math.min( maxFar / absZ, 1.0 ) );
}
} );
return this.vertices;
}
/**
* Splits the CSM frustum by the given array. The new CSM frustum are pushed into the given
* target array.
*
* @param {Array<number>} breaks - An array of numbers in the range `[0,1]` the defines how the
* CSM frustum should be split up.
* @param {Array<CSMFrustum>} target - The target array that holds the new CSM frustums.
*/
split( breaks, target ) {
while ( breaks.length > target.length ) {
target.push( new CSMFrustum() );
}
target.length = breaks.length;
const near = this.vertices.near[ 0 ].z;
const far = this.vertices.far[ 0 ].z;
for ( let i = 0; i < breaks.length; i ++ ) {
const cascade = target[ i ];
if ( i === 0 ) {
for ( let j = 0; j < 4; j ++ ) {
cascade.vertices.near[ j ].copy( this.vertices.near[ j ] );
}
} else {
const alpha = ( breaks[ i - 1 ] * far - near ) / ( far - near );
for ( let j = 0; j < 4; j ++ ) {
cascade.vertices.near[ j ].lerpVectors( this.vertices.near[ j ], this.vertices.far[ j ], alpha );
}
}
if ( i === breaks.length - 1 ) {
for ( let j = 0; j < 4; j ++ ) {
cascade.vertices.far[ j ].copy( this.vertices.far[ j ] );
}
} else {
const alpha = ( breaks[ i ] * far - near ) / ( far - near );
for ( let j = 0; j < 4; j ++ ) {
cascade.vertices.far[ j ].lerpVectors( this.vertices.near[ j ], this.vertices.far[ j ], alpha );
}
}
}
}
/**
* Transforms the given target CSM frustum into the different coordinate system defined by the
* given camera matrix.
*
* @param {Matrix4} cameraMatrix - The matrix that defines the new coordinate system.
* @param {CSMFrustum} target - The CSM to convert.
*/
toSpace( cameraMatrix, target ) {
for ( let i = 0; i < 4; i ++ ) {
target.vertices.near[ i ]
.copy( this.vertices.near[ i ] )
.applyMatrix4( cameraMatrix );
target.vertices.far[ i ]
.copy( this.vertices.far[ i ] )
.applyMatrix4( cameraMatrix );
}
}
}
/**
* Constructor data of `CSMFrustum`.
*
* @typedef {Object} CSMFrustum~Data
* @property {boolean} [webGL] - Whether this CSM frustum is used with WebGL or WebGPU.
* @property {boolean} [reversedDepth] - Whether reversed depth buffer is enabled.
* @property {Matrix4} [projectionMatrix] - A projection matrix usually of the scene's camera.
* @property {number} [maxFar] - The maximum far value.
**/
export { CSMFrustum };