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 Calculating the Reflexion from a slope  (Read 774 times) 0 Members and 1 Guest are viewing this topic.
Serethos

Junior Devvie

Java games rock!

 « Posted 2005-07-22 21:59:23 »

i working on some collision detection, currently on bumping a ball from a slope/diagonal line.
i use the projection of the ball's direction on the slope to get the impact point and test, if the
normal from this point to the ball's center is <= the radius of the ball.

now im searching for a good way of getting the reflection vector. the incoming angle is the
same as the outgoing one ...  but my try looks a little too elaborately..

any good hints ?

Junior Devvie

Java games rock!

 « Reply #1 - Posted 2005-07-23 00:04:22 »

I quickly punched some numbers into a calculator. Try the following formula:

 1  2 `xNew = 2*cos(u)^2*vx - 2*cos(u)*sin(u)*vy - vxyNew = -2*sin(u)*cos(u)*vx - 2*cos(u)^2*vy + vy`

u is the angle of the ball velocity with the edge, vx and vy are coordinates of the velocity.

I could have made a typo somewhere, but I can explain or correct at some other time.
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