Vector matrix multiplication
We have now implemented translation, scaling, and rotation in terms of matrices. These matrices become useful when we can apply their transformations to vectors. How do we apply a matrix transformation to a vector? The same way we do to a matrix: using matrix multiplication!
To multiply a vector and a matrix, we need to think of a vector as a matrix that has only one row or column. This leaves us with an important question, is a vec3 a matrix with one column and three rows, or three columns and one row?
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Row Vector |
Column Vector |
|---|---|
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Pre Multiplication |
Post Multiplication |
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If the vector is on the left side of the matrix, it's a 1 X 3 Row Vector. With a row vector, we use Pre Multiplication.
If the vector is on the right side of the matrix, it's a 3 X 1 Column Vector. With column vectors we use Post Multiplication.
The naming is intuitive, with pre multiplication the vector is placed before the matrix, with post multiplication the vector is placed after the matrix...
