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