Air Hockey collision problem

[poll262]

I am making an air hockey game and am having difficulties getting the puck to bounce off of the paddle in the right direction. Plus sometimes the puck will get stuck inside of the paddle. Here is my code so far.

Turing:

View.Set ("graphics:1000;600, offscreenonly") var paddleX, paddleY, paddleRadius, button : int var ballX, ballY, ballRadius, vx, vy : int ballX := 500 ballY := 300 paddleRadius := 20 ballRadius := 20 vx := (Rand.Int (0, 1) * 2) - 1 vy := (Rand.Int (0, 1) * 2) - 1 procedure graphics     drawarc (0, 300, 90, 90, 270, 90, red)     drawarc (1000, 300, 90, 90, 90, 270, red)     drawfillbox (490, 0, 510, 600, red)     drawfillbox (250, 0, 255, 600, blue)     drawfillbox (750, 0, 755, 600, blue)     drawfilloval (paddleX, paddleY, paddleRadius, paddleRadius, blue)     drawfilloval (ballX, ballY, ballRadius, ballRadius, black) end graphics procedure ballMove     ballX := ballX - vx     ballY := ballY - vy     if Math.Distance (paddleX, paddleY, ballX, ballY) < paddleRadius * 2 then         vx := -vx         vy := -vy     end if     if ballX + ballRadius >= maxx then         vx := -vx     elsif ballX - ballRadius <= 0 then         vx := -vx     end if     if ballY + ballRadius >= maxy then         vy := -vy     elsif ballY - ballRadius <= 0 then         vy := -vy     end if end ballMove loop     mousewhere (paddleX, paddleY, button)     graphics     ballMove     View.Update     cls end loop

[Zren]

> Plus sometimes the puck will get stuck inside of the paddle.

That's because you move your position before checking if being in that position collides with something.

> bounce off of the paddle in the right direction.

What's happening is that, no matter the angle the two objects collide at, the puck will inverse it's direction. This is similar to shooting at a wall at any weird angle, and the bullet rebounding right back at you.

To quote this dude, "For perfect particles (& light) the angle of reflection is equal to the angle of incidence, as illustrated by this diagram (from commons.wikimedia.org)."


http://upload.wikimedia.org/wikipedia/commons/2/24/Angle_of_Reflection_(PSF).png

So, since the walls are along the planes, getting the resulting vector is fairly easy. To get a proper reflection of the two circles, we first need to know what we're bouncing off of.



This shows the process a bit. We're bouncing off the line perpendicular to the vector from one center of a circle to the next.

As for the math of what you need to do... Well, I'll leave that to someone who's actually done that before.

[Raknarg]

That doesnt seem right to me. What your'e saying is that at any given angle, they will reflect perpendicularly? That's wrong.

[poll262]

Also how can I use two different radius's to for the puck and the paddle. Whenever I use different radius's, Math.Distance will no longer work to detect when they are touching.

[Raknarg]

if Math.Distance (x1, y1, x2, y2) <= radius1 + radius 2 then ...

[poll262]

Thanks that works. Now can someone explain to me what vectors are and how I can use then to get the puck to bounce off the paddle in the proper direction.

[Raknarg]

Ever worked with trigonometry before? Cause if you haven't, I'm going to let someone else explain it

[poll262]

I have done trig before I just do not know what a vector is.