Fix RayCastSensor frame offset alignment for site/geom frames#778
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kevinzakka merged 1 commit intomainfrom Mar 11, 2026
Merged
Fix RayCastSensor frame offset alignment for site/geom frames#778kevinzakka merged 1 commit intomainfrom
kevinzakka merged 1 commit intomainfrom
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When a RayCastSensor is attached to a site or geom with a local offset, ray_alignment="yaw" and "world" only aligned ray directions and pattern offsets. The frame position was read directly from MuJoCo's site_xpos, which bakes in the full body rotation on the offset. This caused the ray origin to swing with body pitch/roll. The fix decomposes the frame position for site/geom frames: instead of reading site_xpos, recompute it as body_pos + alignment(body_mat) @ frame_local_pos. For "base" alignment this is identical to the previous behavior. For "yaw" and "world", the offset now respects the alignment mode. The same decomposition is applied in debug_vis() so visualization matches the actual ray computation. Fixes #775
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When a RayCastSensor is attached to a site or geom with a local offset from its parent body,
ray_alignment="yaw"and"world"only aligned ray directions and pattern offsets. The frame position itself was read directly from MuJoCo'ssite_xpos, which bakes in the full body rotation on the offset. This caused the ray origin to swing with body pitch/roll, defeating the purpose of alignment.The fix decomposes the frame position for site/geom frames: instead of reading the pre-baked
site_xpos, recompute it asbody_pos + alignment(body_mat) @ frame_local_pos. For"base"alignment this is identical to the previous behavior. For"yaw"and"world", the offset now respects the alignment mode. The same decomposition is applied indebug_vis()so visualization matches the actual ray computation.Before.
raycast_before_fix.mp4
After.
raycast_after_fix.mp4
--frame site --alignment yaw --pitchin the raycast sensor demo. The body oscillates in pitch with the site 2m above. Before: ray origin swings with pitch. After: ray origin stays directly above the body.Fixes #775