In the event that you wanted the new angle to be a reflection off of the target platform surface (like a ball ricocheting off a wall on a pool table), which is what I understand from your written description, you'll want to do the following:
Man, I confess I mess up hard when trying to explain this xD
I don't think it has something to do with reflection. Dop2000 already mentioned Reflection on another topic I made, but I don't think it does the trick in this case, since I'll have many different objects to land on in many different orientations. Reflection would retrieve a different angle based on how the ray collides. What I want to achieve is the same angle everytime I jump.
My fourth try trying to explain this, here I go xD
What I want to achieve is:
Let's say I'm on a wall right side (right edge). I want to jump off this wall towards another area and obj_PlayerPointer angle is, at this moment, 45 degrees, pointing Southeast - as Construct angle 0 is East. The platform I'm pointing to and going to land afterwards is a floor - going to land on it's top edge.
Then, as soon as I press Space Bar and jump, I want that obj_PlayerPointer get it's angle set to a new value, and this value being a value that results on the same angle difference obj_PlayerPointer had in relation to the previous edge I was at, the edge I jumped from.
And I want it to always do it, every time the player jumps!
Here is another drawing: prntscr.com/r97wxx
The angle doesn't need to be 45. I just want obj_PlayerPointer to maintain the angle - the one used on the previous jump - for the next jump, no matter what angle was used.