import { Vector3, Matrix4 } from 'three';
const inverseProjectionMatrix = new Matrix4();
class CSMFrustum {
constructor( data ) {
data = data || {};
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 );
}
}
setFromProjectionMatrix( projectionMatrix, maxFar ) {
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, - 1 );
this.vertices.near[ 1 ].set( 1, - 1, - 1 );
this.vertices.near[ 2 ].set( - 1, - 1, - 1 );
this.vertices.near[ 3 ].set( - 1, 1, - 1 );
this.vertices.near.forEach( function ( v ) {
v.applyMatrix4( inverseProjectionMatrix );
} );
this.vertices.far[ 0 ].set( 1, 1, 1 );
this.vertices.far[ 1 ].set( 1, - 1, 1 );
this.vertices.far[ 2 ].set( - 1, - 1, 1 );
this.vertices.far[ 3 ].set( - 1, 1, 1 );
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;
}
split( breaks, target ) {
while ( breaks.length > target.length ) {
target.push( new CSMFrustum() );
}
target.length = breaks.length;
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 {
for ( let j = 0; j < 4; j ++ ) {
cascade.vertices.near[ j ].lerpVectors( this.vertices.near[ j ], this.vertices.far[ j ], breaks[ i - 1 ] );
}
}
if ( i === breaks.length - 1 ) {
for ( let j = 0; j < 4; j ++ ) {
cascade.vertices.far[ j ].copy( this.vertices.far[ j ] );
}
} else {
for ( let j = 0; j < 4; j ++ ) {
cascade.vertices.far[ j ].lerpVectors( this.vertices.near[ j ], this.vertices.far[ j ], breaks[ i ] );
}
}
}
}
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 );
}
}
}
export { CSMFrustum };
