Okay so, Im trying to create a lightning particle effect in godot, for that ive created a GPUParticles3D Node with Amount 1 and lifetime 1s with a QuadMesh as the Mesh and a visual shader as the material.
The texture is a 3x3 of in total 9 lightning bolts on a 3000x3000px image each bolt is 1000x1000px, now I want to randomise which lightning bolt gets displayed

how do i do that?
I tried it already this way (2nd pic) but it just cycles through them without any randomness and just displays the 1st, 5th and 9th image if I input both x and y into the vectorcompose node (if its just x its the 1st, 2nd and 3rd, and if only y as the input its 1st, 4th and 7th image.) Help would be appreciated, thanks in advance!