Get coordinates of a point when it reaches Y value

[marius]

Hey all, I have some math troubles again.
I am launching an object in a direction, and its gonna move until it reaches a certain Y value. I can use events to avoid the math in this, and just do a for-loop and check every pixel moving is Y position equals the Y position I want (which I think is really unprofessionally), but I would like to know the math so I can do this calculation in 1 event.

Here is an illustration:


So basically, if the object is at position (400,400) and its gonna move in the 135 degrees direction until Y position is 100, how can I predict X?

[BartekB]

The expression to finding "Position I need to know"'s X relative to Start Position of object's X is simply:

( ( ObjectY - Y Value ) * 1.0 / Sin( 180 - Angle ) ) * Sin( Angle )

EDIT: Example attached
EDIT: Woops, apparently it's always 135 degrees, no matter what you change the angle to

[marius]

Ah, shoot, it looked right! Yes, the 135 degrees may wary..

[BartekB]

This time I got it right, it's:

( Tan(180 - Angle ) * (ObjectY - YValue ) )

[marius]

Yes, this is right!
Thanks a lot