[with solution] Jitter when modifying both the Camera and the Ortho (and one unneedded render)

[tmarti]

In src/viewer/scene/camera/Ortho.js file:

https://github.com/xeokit/xeokit-sdk/blob/13dbc2956b0305d448499bc3f6e96b9c344be97d/src/viewer/scene/camera/Ortho.js#L102

https://github.com/xeokit/xeokit-sdk/blob/13dbc2956b0305d448499bc3f6e96b9c344be97d/src/viewer/scene/camera/Ortho.js#L136

https://github.com/xeokit/xeokit-sdk/blob/13dbc2956b0305d448499bc3f6e96b9c344be97d/src/viewer/scene/camera/Ortho.js#L168

Those lines mean than whenever some of the properties of the Ortho class are modified, a render will be triggered during next tick, not the current one.

This creates some jittering in some cases where we modify both the Camera properties (rendered on the current tick) and the Ortho properties (rendered on the next tick) at the same time. As a side effect, in that case two renders are triggered.

Shouldn't those lines be...

this._needUpdate(0);

... instead of...

this._needUpdate();

... so that Ortho changes are processed during the current tick (and not enqueued for the next tick)?

Did some tests with that change and the effect is that the problems are solved:

• only one render is triggered when modifying both the Camera and the Ortho instead of two
• the jitter disappears

[xeolabs]

Oh yes, good spotting. That call should indeed be:

this._needUpdate(0);

Avoiding the double-update, when modifying view or projection matrices, is the reason for that 0 priority, yes.

[xeolabs]

Fixed in https://github.com/xeokit/xeokit-sdk/commit/d785a884babe74ddb7c58c8103af6f10dcafe077