Improve 3D Map View movement performance #60246
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Previously the entire camera change was handled on every input event, which led to slowdown and stutters, since we can get ~1000/s such events with common mice. We don't care about intermediate camera states and can only process the last state before rendering.
Previously the average could be computed on every mouse move event. This is a problem, since the loop can be slow, especially on debug builds where nothing gets inlined.
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Tests failed for Qt 6One or more tests failed using the build from commit ee6d434 dem_terrain_filtered_2 (testFilteredDemTerrain)dem_terrain_filtered_2Test failed at testFilteredDemTerrain at tests/src/3d/testqgs3drendering.cpp:1927 Rendered image did not match tests/testdata/control_images/3d/expected_dem_terrain_filtered_2/expected_dem_terrain_filtered_2.png (found 103123 pixels different) depth_retrieve_image (testDepthBuffer)depth_retrieve_imageTest failed at testDepthBuffer at tests/src/3d/testqgs3drendering.cpp:2098 Rendered image did not match tests/testdata/control_images/3d/expected_depth_retrieve_image/expected_depth_retrieve_image.png (found 307008 pixels different) debug_map_1 (testDebugMap)debug_map_1Test failed at testDebugMap at tests/src/3d/testqgs3drendering.cpp:2235 Rendered image did not match tests/testdata/control_images/3d/expected_debug_map_1/qt6/expected_debug_map_1.png (found 3510 pixels different) virtual_pointcloud_3d_overview (testPointCloud3DOverview)virtual_pointcloud_3d_overviewTest failed at testPointCloud3DOverview at tests/src/3d/testqgspointcloud3drendering.cpp:603
The full test report (included comparison of rendered vs expected images) can be found here. Further documentation on the QGIS test infrastructure can be found in the Developer's Guide. |
Tests failed for Qt 5One or more tests failed using the build from commit ee6d434 depth_wheel_action_3 (testDepthBuffer)depth_wheel_action_3Test failed at testDepthBuffer at tests/src/3d/testqgs3drendering.cpp:2148 Rendered image did not match tests/testdata/control_images/3d/expected_depth_wheel_action_3/expected_depth_wheel_action_3.png (found 23775 pixels different) debug_map_2 (testDebugMap)debug_map_2Test failed at testDebugMap at tests/src/3d/testqgs3drendering.cpp:2249 Rendered image did not match tests/testdata/control_images/3d/expected_debug_map_2/expected_debug_map_2.png (found 520 pixels different) virtual_pointcloud_3d_overview (testPointCloud3DOverview)virtual_pointcloud_3d_overviewTest failed at testPointCloud3DOverview at tests/src/3d/testqgspointcloud3drendering.cpp:603
The full test report (included comparison of rendered vs expected images) can be found here. Further documentation on the QGIS test infrastructure can be found in the Developer's Guide. |
Description
This PR improves the performance of the 3D map view, specifically removing some large stutters when moving the camera.
Currently, all work associated with camera movement (incl. finding which chunks should be visible and loading them) is done in the mouse movement event handler. This is an issue, since such events can come 1000 times a second with standard mice. These events accumulate and overrun the main thread, resulting in stutters.
With this PR, I've changed the event handler to only do the necessary event-specific computations, while leaving the rest to be done at the start of the frame.
I've also added some caching to
QgsCameraController::sampleDepthBuffer, which sometimes computes the average depth over the whole depth buffer. This was also happening on every mouse move event and took >20ms on my machine (though release builds are likely to be faster due to inlining, I haven't checked). In this PR, I've added a cache, so this only happens once per frame.I've also added some new
QgsEventTracingtrace points which were helpful with analysing performance and finding issues.