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opensim-org / three.js

JavaScript 3D library.
http://threejs.org/
MIT License
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Camera zooms like Zeno's "Achilles and the tortoise" paradox #22

Open tkuchida opened 7 years ago

tkuchida commented 7 years ago

Zoom sensitivity increases with greater magnification. The result is that it can be impossible to get close to an object (e.g., marker), depending on the camera position and model pose.

Pan sensitivity also increases when zoomed in. Tilt sensitivity does not change, so a large mouse displacement is necessary to pan but a similar mouse displacement causes a huge change in tilt.

Tested only on Windows/Chrome/Python3.5.2.

tkuchida commented 7 years ago

I can't seem to reproduce the issue exactly as I encountered it originally, but here's an example.

Load the model and zoom in. The zoom sensitivity always increases eventually, but it seems to be dependent on the model's bounding box rather than what's in the display or what's highlighted. As a result, depending on the camera position and model pose, the zoom sensitivity may start increasing noticeably as you approach a bone (e.g., approaching the knee from the back), or may start increasing noticeably only after the camera has passed the bone (e.g., approaching the knee from the front).

aymanhab commented 7 years ago

Will have to read about the paradox first. Thanks for reporting.

tkuchida commented 7 years ago

Will have to read about the paradox first.

Ah, sorry. The question is: how many hops will it take for you to reach a destination if you hop half the distance each time? The analogy is "one hop" = "one click of my wheel mouse". :rabbit::turtle: