It’s a point in the right direction, but I’m going to have to do a lot of work to figure out how to structure that into a function which determines the direction.
I can see how with the object plane’s translate co-ordinates I should be able to calculate the direction it is facing in relation to my particles direction (past and current locations) but it seems like the long way around - and I’m not sure I have the skills to code all that together within my timeframe.
It strikes me however that Maya automatically calculates which direction to send the particle after impact, and this is equal to the angle with which it was struck. If I can find the var/attribute for that angle, I can multiply it by a new variable (determined by the index of refraction I assign to the object and an if/else statement to determine critical angle) to give me the resulting angle of refraction.
I’m not sure if this method is entirely possible, but it seems like the way to approach the problem.