To manipulate object transformations with matrices, Blender includes the “mathutils” module in which the “Matrix” class is defined. With this class, you can simply create the necessary transformation matrices – translation, rotation, and scale.

The following command is used to create a scale matrix:

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from mathutils import Matrix scale_matrix = Matrix.Scale(SCALE_VALUE, MATRIX_SIZE, AXIS) |

where:

SCALE_VALUE – the multiplier. How many times you need to change the scale with the resulting matrix,

MATRIX_SIZE – the size of the resulting matrix,

AXIS – a vector that determines on which axes the object will be scaled with the resulting matrix.

For example, to create a matrix of 2x scaling along the X-axis, you need to execute the following:

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scale_matrix_x2 = Matrix.Scale(2, 4, (1.0, 0.0, 0.0)) |

Everything looks simple, but this method has one non-obvious feature.

If you need to create a scaling matrix along all three axes simultaneously, it seems logical to specify all the axes in the “AXES” parameter when calling this method :

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scale_matrix_all2 = Matrix.Scale(2, 4, (1.0, 1.0, 1.0)) |

But this doesn’t work, the resulting matrix is not correct!

To create a scaling matrix along all three axes, you need to create separate scaling matrices for each of the axes and then multiply them:

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scale_matrix_x2 = Matrix.Scale(2, 4, (1.0, 0.0, 0.0)) scale_matrix_y2 = Matrix.Scale(2, 4, (0.0, 1.0, 0.0)) scale_matrix_z2 = Matrix.Scale(2, 4, (0.0, 0.0, 1.0)) scale_matrix_xall = scale_matrix_x2 @ scale_matrix_y2 @ scale_matrix_z2 |

Now we get the correct matrix for scaling along three axes.

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