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- # Copyright (c) 2018-present, Facebook, Inc.
- # All rights reserved.
- #
- # This source code is licensed under the license found in the
- # LICENSE file in the root directory of this source tree.
- #
- import torch
- def qrot(q, v):
- """
- Rotate vector(s) v about the rotation described by quaternion(s) q.
- Expects a tensor of shape (*, 4) for q and a tensor of shape (*, 3) for v,
- where * denotes any number of dimensions.
- Returns a tensor of shape (*, 3).
- """
- assert q.shape[-1] == 4
- assert v.shape[-1] == 3
- assert q.shape[:-1] == v.shape[:-1]
- qvec = q[..., 1:]
- uv = torch.cross(qvec, v, dim=len(q.shape)-1)
- uuv = torch.cross(qvec, uv, dim=len(q.shape)-1)
- return (v + 2 * (q[..., :1] * uv + uuv))
-
-
- def qinverse(q, inplace=False):
- # We assume the quaternion to be normalized
- if inplace:
- q[..., 1:] *= -1
- return q
- else:
- w = q[..., :1]
- xyz = q[..., 1:]
- return torch.cat((w, -xyz), dim=len(q.shape)-1)
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