Represent a shear transformation by angle in the direction of the first vector,
ShearingTransform[θ, v, n]
ShearingTransform[θ, v, n, p]
ShearingTransform[Pi/4, {1, 0}, {0, 1}]
→ TransformationFunction[{{1, 1, 0}, {0, 1, 0}, {0, 0, 1}}]ShearingTransform[Pi/6, {3, 4}, {0, 1}]
→ TransformationFunction[{{1, 1/Sqrt[3], 0}, {0, 1, 0}, {0, 0, 1}}]ShearingTransform[Pi/4, {1, 0}, {0, 1}, {2, 3}]
→ TransformationFunction[{{1, 1, -3}, {0, 1, 0}, {0, 0, 1}}]