Ball Bouncing Trig

ello, i am trying to have a ball bounce around the screen but i want to be able to draw lines and have the ball bounce off of the line accordingly. Unfortunately i am only in Pre-calc and have not learned enough to be sufficient. I've been trying to decipher the physics in this ACTIONSCRIPT CODE

Code:

---

ACTIONSCRIPT:

  1.
      _root.attachMovie("arrow", "arrow", 10001);
  2.
      _root.attachMovie("bounce", "bounce", 1000);
  3.
      arrow._x = 150;
  4.
      arrow._y = 150;
  5.
      bounce._x = 150;
  6.
      bounce._y = 150;
  7.
      arrow.onEnterFrame = function() {
  8.
          mousex = _xmouse-150;
  9.
          mousey = (_ymouse-150)*-1;
  10.
          angle = Math.atan(mousey/mousex)/(Math.PI/180);
  11.
          if (mousex<0) {
  12.
              angle += 180;
  13.
          }
  14.
          if (mousex>=0 && mousey<0) {
  15.
              angle += 360;
  16.
          }
  17.
          bounce_angle = 180-angle;
  18.
          if (bounce_angle<0) {
  19.
              bounce_angle += 360;
  20.
          }
  21.
          _root.angletext.text = "Angle: "+angle;
  22.
          _root.bouncetext.text = "Angle: "+bounce_angle;
  23.
          this._rotation = angle*-1;
  24.
          bounce._rotation = -bounce_angle;
  25.
      };

---

but i can't seem to get it to work.
This is the code that i have so far.

Code:

---

Dim mousex, mousey As Double
Dim AendX, AendY As Double
Dim linelength As Single
Dim angle As Single
Const Pi As Double = 3.1415926
Dim AngleRadians As Double
Dim AngleDegrees As Double

Private Sub Form_MouseMove(Button As Integer, Shift As Integer, X As Single, Y As Single)
mousex = X
mousey = Y
End Sub

Private Sub Timer1_Timer()
arrow.X2 = mousex
arrow.Y2 = mousey
AendX = mousex - linelength
AendY = mousey - linelength
linelength = Sqr((arrow.X2 - arrow.X2) ^ 2 + (arrow.Y2 - arrow.Y1) ^ 2)
Label1.Caption = linelength
AngleDegrees = Atn(mousey / mousex) / (Pi / 180)
Label2.Caption = AngleDegrees
End Sub

---

Right now i am trying just to get the core trig out of the way using this
http://img165.imageshack.us/img165/296/showjy8.jpg
The x2,y2 coords follow the mouse and i'm trying to find the angle which the line makes with the flat line(landscape)

Please help me and please try to explain the trig easily :)

Moved To Games and Graphics Programming

Ah... Trigonometry. Bane of the unwary. :)

Here's how you can determine the angle given by any two points, in radians:

Code:

---

angle = Math.Atan2((Point1.X - Point2.X), (Point1.Y - Point2.Y))

---

To work out the bounceangle from two angles, think about the logic involved: The bounce angle is the entry angle plus x*2 (see attachment).

So you need to work out the ground normal, which is easy: simply add PI/2)radians or 90 degrees to your ground angle.

Then take away the entry angle from your ground normal to give you "x", and add x*2 to your entry angle to get your bounce angle.

Hope this helps,
Qu.