[3d] Large scene support: shift scene's origin if the camera got too far #60869
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uclaros
reviewed
Mar 6, 2025
This should greatly improve our capability to handle large scenes (e.g. more than 50km across) Also add a checkbox to the debug panel to allow devs temporarily turn it off.
wonder-sk
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Relax the assumption that origin is always in the center of the scene
Origin may get updated in Qgs3DMapScene constructor, so let's set ours once the Qgs3DMapScene is constructed
nyalldawson
approved these changes
Mar 11, 2025
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Looks fantastic -- great work @wonder-sk !! |
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This "origin rebasing" or "origin shifting" technique is commonly used in various 3D engines when dealing with large scenes (where objects need double precision coordinates). It should greatly improve our capability to handle large scenes (e.g. more than 50km across)
For now, I have used a simple rule that when camera gets 10 km away from the world's origin, the origin is shifted (and camera is placed at the origin). The origin shift has a bit of a cost (we're updating 4x4 transform matrices of all active nodes), so we prefer not to do it on every camera change, but only when necessary. That said, I have not seen slowdowns when origin gets shifted.
Also add a checkbox to the debug panel to allow devs temporarily turn it off.
A related philosophical question from Futurama:
Before:
simplescreenrecorder-2025-03-05_15.31.36.mp4
After:
simplescreenrecorder-2025-03-05_15.34.44.mp4