opengl - Orders of Modifying the Shape -

i started learning transformations in opengl, , confused steps of modifying shape different position, angles or sizes.

for example, have house in 2d scene follow:

let's want transforms scene in (a) scene in part (b) of house, how should decide whether should scale it, translate or rotate first ? outcome going different ?

thank you.

the outcome going different based on order of transforms.

here pseudocode answers question directly (assuming each function takes x,y,z parameters):

translate(-6, 0, 0) rotate(0, 0, 135) scale(2, 1, 1) 

now let's @ why order matters!

first, have without transforms:

next, let's see happens when rotate counter-clockwise 45° , translate along positive x axis:

notice how translation caused square move toward top-right corner? because rotation transform modifies local axes. positive x points top-right. if rotated 180° +x point towards left instead of right.

now let's @ happens when perform same transforms in reverse order:

this time translation moved square right expected. after square rotated.

check out open.gl page on transformations more detail, around math behind of this.