depth issue in multimarker_pattern_threejs.html

[ThorstenBux]

Issue by jeromeetienne
Tuesday Feb 09, 2016 at 06:30 GMT
Originally opened as https://github.com/artoolkit/jsartoolkit5/issues/2

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in this examples, it seems to have a depth issue which make it flicker all the time.

[ThorstenBux]

Comment by jeromeetienne
Thursday Feb 25, 2016 at 13:05 GMT

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hmm @philip-lamb im thinking it may be due to the camera parameter reading... what do you think ?

Supposition:

• like the camera generated from the parameter would have a near/far very distant from each other
• this would create a massive z-figthing

would that be possible ?

[ThorstenBux]

Comment by philip-lamb
Thursday Feb 25, 2016 at 20:12 GMT

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Z-fighting would cause that, and yes, poorly chosen near/far would cause z-fighting. The camera parameter doesn't directly set the near/far planes, but the camera parameters are merged with the requested near/far values to create the projection matrix. I would need to investigate where those values are set.

[ThorstenBux]

Comment by philip-lamb
Monday Feb 29, 2016 at 05:51 GMT

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Near and far planes appear to be set here: https://github.com/artoolkit/jsartoolkit5/blob/master/js/artoolkit.api.js#L960

These need to be made configurable.

[ThorstenBux]

Comment by jeromeetienne
Monday Feb 29, 2016 at 11:31 GMT

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Changing those values doesnt affect the issue unfortunatly. This line seems to be the source of it

camera.projectionMatrix.elements.set(this.getCameraMatrix());

When i replace it with a approximation of it, all flickering issues disapear. This is bypassing camera parameters loading tho.

            camera = new THREE.PerspectiveCamera( 43, 640 / 480, 1, 2000 );
            camera.lookAt(new THREE.Vector3(0,0,1))
            camera.rotateZ(Math.PI)

[ThorstenBux]

Comment by jeromeetienne
Wednesday Mar 02, 2016 at 14:01 GMT

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my bet is that the near/far we use when we compute the projection matrix in jsartoolkit are too far apart.

im not sure where to check this supposition tho...

[ThorstenBux]

Comment by yvt
Thursday Nov 23, 2017 at 09:26 GMT

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@jeromeetienne You are right; they default to 0.0001 and 1000.0. And currently, there is no way to change them because setProjectionNearPlane and setProjectionFarPlane just store the new near/far values to member variables and do not actually recalculate the projection matrix.

[ThorstenBux]

We should make Near and far planes configurable.