Fix for stray point in center of screen

[sir-chaos]

A stray point appeared in the center of screen instead of discarding under some systems when there were points with show = false style.
This should fix the issue.
See #5598

[lilleyse]

Hm unfortunately I don't think this fix works on my end. It seems like my hardware does not allow point sizes smaller than 1.

var viewer = new Cesium.Viewer('cesiumContainer');

var scene = viewer.scene;
var tileset = scene.primitives.add(new Cesium.Cesium3DTileset({
    url : '../../../Specs/Data/Cesium3DTiles/PointCloud/PointCloudWithPerPointProperties/'
}));

tileset.readyPromise.then(function() {
    var boundingSphere = tileset.boundingSphere;
    viewer.camera.viewBoundingSphere(boundingSphere, new Cesium.HeadingPitchRange(0.0, -1.0, 50.0));
    viewer.camera.lookAtTransform(Cesium.Matrix4.IDENTITY);
}).otherwise(function(error) {
    throw(error);
});

tileset.style = new Cesium.Cesium3DTileStyle({
    pointSize : 5,
    show : '${POSITION}[0] > 0.0'
});

[lilleyse]

Just for testing, does substituting with code like:

vs += ' gl_Position.x += (1.0 - show) * 5.0; \n';

work for you?

Edit: actually this code is not super reliable as it fails depending on the current projection matrix.

[sir-chaos]

Unfortunately I don't have access to workstation where the bug showed up at the moment (on my current system all works fine). If the suggesteed fix fails in your situation, maybe nullification for both gl_Position and gl_PointSize would help?

[lilleyse]

Yeah that approach sounds good.

[lilleyse]

I made the change here. Does that work on your end too?

Also please add yourself to CONTRIBUTORS.md.

[rjeli]

Thank you, this fixed it for me as well, had the point at center of screen and could not zoom. Now works perfectly. Chrome on Ubuntu with Nvidia card.

[mramato]

@lilleyse what's the status of this PR?

[lilleyse]

Should be ready to merge.

[pjcozzi]

@lilleyse please update CHANGES.md in master if you haven't already.

@sir-chaos can you please add yourself to CONTRIBUTORS.md and send in a Contributor License Agreement since this PR includes one of your commits?

[lilleyse]

Updated CHANGES.md here: 2d6a5cf