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Matrix multiply instead of dot

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This commit is contained in:
Chris Hodapp 2019-09-27 22:24:43 +02:00
parent a6a429f298
commit 3c74135a4e
1 changed files with 7 additions and 7 deletions
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14
meshutil.py
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@ -28,12 +28,8 @@ class FaceVertexMesh(object):
m2 = FaceVertexMesh(v2, f2) m2 = FaceVertexMesh(v2, f2)
return m2 return m2
def transform(self, xform): def transform(self, xform):
# Pass a Transform # Just transform vertices. Indices don't change.
vh = numpy.hstack([self.v, numpy.ones((self.v.shape[0], 1), dtype=self.v.dtype)]) return FaceVertexMesh(xform.apply_to(self.v), self.f)
v2 = vh.dot(xform.mtx.T)[:,0:3]
# TODO: why transpose?
# TODO: fix homogenous (even if I don't use it)
return FaceVertexMesh(v2, self.f)
def to_stl_mesh(self): def to_stl_mesh(self):
data = numpy.zeros(self.f.shape[0], dtype=stl.mesh.Mesh.dtype) data = numpy.zeros(self.f.shape[0], dtype=stl.mesh.Mesh.dtype)
v = data["vectors"] v = data["vectors"]
@ -48,6 +44,7 @@ class Transform(object):
else: else:
self.mtx = mtx self.mtx = mtx
def _compose(self, mtx2): def _compose(self, mtx2):
# Note pre-multiply. Earlier transforms are done first.
return Transform(mtx2 @ self.mtx) return Transform(mtx2 @ self.mtx)
def scale(self, *a, **kw): def scale(self, *a, **kw):
return self._compose(mtx_scale(*a, **kw)) return self._compose(mtx_scale(*a, **kw))
@ -56,8 +53,11 @@ class Transform(object):
def rotate(self, *a, **kw): def rotate(self, *a, **kw):
return self._compose(mtx_rotate(*a, **kw)) return self._compose(mtx_rotate(*a, **kw))
def apply_to(self, vs): def apply_to(self, vs):
# Homogeneous coords, so append a column of ones. vh is then shape (N,4):
vh = numpy.hstack([vs, numpy.ones((vs.shape[0], 1), dtype=vs.dtype)]) vh = numpy.hstack([vs, numpy.ones((vs.shape[0], 1), dtype=vs.dtype)])
return vh.dot(self.mtx.T)[:,0:3] # As we have row vectors, we're doing basically (A*x)^T=(x^T)*(A^T)
# hence transposing the matrix, while vectors are already transposed.
return (vh @ self.mtx.T)[:,0:3]
def mtx_scale(sx, sy=None, sz=None): def mtx_scale(sx, sy=None, sz=None):
if sy is None: if sy is None: