Transformations in the geom3d Package
Description
Examples
The help page geom3d/transformation describes the transformations that can be applied directly to a specific geometric object.
In general, to define a transformation without specifying the object to which the transformation is to be applied, use the "verb" form of the above transformations.
rotation
rotate
translation
translate
ScrewDisplacement
ScrewDisplace
reflection
reflect
RotatoryReflection
RotatoryReflect
GlideReflection
GlideReflect
homothety
dilate
homology
StretchRotate
Using the function geom3d[inverse], one can compute the inverse of a given product of transformations, the function geom3d[transprod] converts a given transformation or product of transformations into a product of three "primitive" transformations (translate, rotate, and dilate), while the function geom3d[transform] is to apply the "result" transformation to a specific geometric object.
with⁡geom3d:
Define t1 which is a homothety with ratio 3, center of homothety (0,0,0)
t1≔dilate⁡3,point⁡o,0,0,0
t1≔dilate⁡3,o
Define the plane oxz
point⁡A,1,0,0,point⁡B,0,0,1:
line⁡l1,o,A,line⁡l2,o,B,plane⁡p,l1,l2:
dsegment⁡AB,A,B:
Define t2 which is a glide-reflection with p as the plane of reflection and AB as the vector of translation
t2≔GlideReflect⁡p,AB
Define t3 as a screw-displacement with l3 as the rotational axis and AB as a vector of translation
t3≔ScrewDisplace⁡π2,line⁡l3,A,B,AB
t3≔ScrewDisplace⁡π2,l3,AB
Compute q1 which is the product of t2t1⁢t3
q1≔transprod⁡t2t1,t3
q1≔transprod⁡dilate⁡13,o,reflect⁡p,translate⁡AB,dilate⁡3,o,rotate⁡π2,l3,translate⁡AB
Compute the inverse of q1
q2≔inverse⁡q1
q2≔transprod⁡translate⁡_AB,rotate⁡3⁢π2,l3,dilate⁡13,o,translate⁡_AB,reflect⁡p,dilate⁡3,o
Compute the product of q1⁢q2; one can quickly recognize that this is an identity transformation
q≔transprod⁡q1,q2
q≔transprod⁡dilate⁡13,o,reflect⁡p,translate⁡AB,dilate⁡3,o,rotate⁡π2,l3,translate⁡AB,translate⁡_AB,rotate⁡3⁢π2,l3,dilate⁡13,o,translate⁡_AB,reflect⁡p,dilate⁡3,o
Simple check
tetrahedron⁡te,o,1
te
transform⁡te1,te,q
te1
AreDistinct⁡te,te1
false
Hence, the two objects are the same
See Also
geom3d/objects
geom3d/transformation
geom3d[draw]
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