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/**
* @author jsantell / https://www.jsantell.com/
* @author mrdoob / http://mrdoob.com/
*/
import { Vector3 } from '../../math/Vector3.js';
var cameraLPos = new Vector3();
var cameraRPos = new Vector3();
/**
* Assumes 2 cameras that are parallel and share an X-axis, and that
* the cameras' projection and world matrices have already been set.
* And that near and far planes are identical for both cameras.
* Visualization of this technique: https://computergraphics.stackexchange.com/a/4765
*/
function setProjectionFromUnion( camera, cameraL, cameraR ) {
cameraLPos.setFromMatrixPosition( cameraL.matrixWorld );
cameraRPos.setFromMatrixPosition( cameraR.matrixWorld );
var ipd = cameraLPos.distanceTo( cameraRPos );
var projL = cameraL.projectionMatrix.elements;
var projR = cameraR.projectionMatrix.elements;
// VR systems will have identical far and near planes, and
// most likely identical top and bottom frustum extents.
// Use the left camera for these values.
var near = projL[ 14 ] / ( projL[ 10 ] - 1 );
var far = projL[ 14 ] / ( projL[ 10 ] + 1 );
var topFov = ( projL[ 9 ] + 1 ) / projL[ 5 ];
var bottomFov = ( projL[ 9 ] - 1 ) / projL[ 5 ];
var leftFov = ( projL[ 8 ] - 1 ) / projL[ 0 ];
var rightFov = ( projR[ 8 ] + 1 ) / projR[ 0 ];
var left = near * leftFov;
var right = near * rightFov;
// Calculate the new camera's position offset from the
// left camera. xOffset should be roughly half `ipd`.
var zOffset = ipd / ( - leftFov + rightFov );
var xOffset = zOffset * - leftFov;
// TODO: Better way to apply this offset?
cameraL.matrixWorld.decompose( camera.position, camera.quaternion, camera.scale );
camera.translateX( xOffset );
camera.translateZ( zOffset );
camera.matrixWorld.compose( camera.position, camera.quaternion, camera.scale );
camera.matrixWorldInverse.getInverse( camera.matrixWorld );
// Find the union of the frustum values of the cameras and scale
// the values so that the near plane's position does not change in world space,
// although must now be relative to the new union camera.
var near2 = near + zOffset;
var far2 = far + zOffset;
var left2 = left - xOffset;
var right2 = right + ( ipd - xOffset );
var top2 = topFov * far / far2 * near2;
var bottom2 = bottomFov * far / far2 * near2;
camera.projectionMatrix.makePerspective( left2, right2, top2, bottom2, near2, far2 );
}
export { setProjectionFromUnion };
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