Step 1: In ordinary 3D coordinates, translation is an addition, while scaling and rotation are matrix multiplications. Mixing addition and multiplication makes it hard to combine transformations.
Step 2: Homogeneous coordinates add a fourth component, writing a point as \( (x, y, z, 1) \). This lets translation also be written as a matrix multiplication.
Step 3: With all transformations as 4x4 matrices, a whole sequence can be multiplied into one composite matrix and applied uniformly.
Step 4: So the purpose is to perform transformations using matrix multiplication.