Angle Collisions

[james2464]

I finally got it.  Had to make use of _ATAN2 and that made a huge difference.  I didn't know what it meant but it's a great command for this.  Without using degrees it captures the radian value of any x,y position and you can add and subtract these radian values to get a reflection.    That makes this simple.  I threw out most of my code once I got this concept going.

Code: (Select All)

'vector reflection demo
'james2464

Screen _NewImage(800, 600, 32)

Const PI = 3.141592654#


Dim c(10) As Long
c(0) = _RGB(30, 30, 30)
c(1) = _RGB(255, 255, 255)
c(2) = _RGB(255, 255, 0)
c(3) = _RGB(255, 0, 0)
c(4) = _RGB(0, 255, 0)
c(5) = _RGB(0, 255, 255)


'0,0 origin
xx = 400
yy = 300


na = 45 'wall starting angle (mouse wheel controlled)

flag = 0
Do

    _Limit 50
    Cls

    '=====================================================
    mouseclick1 = 0

    Do While _MouseInput
        na = na + _MouseWheel * 5
    Loop
    mx% = _MouseX
    my% = _MouseY
    If mx% < xx - 400 Then mx% = xx - 400
    If mx% > xx + 400 Then mx% = xx + 400
    If my% < yy - 300 Then my% = yy - 300
    If my% > yy + 300 Then my% = yy + 300
    lc% = _MouseButton(1)
    If lc% = -1 Then mouseclick1 = 1

    x = 0 - xx + mx%
    y = yy - my%


    '=====================================================
    h = _Hypot(-x, y)

    '=====================================================
    'origin lines
    Line (0, yy)-(800, yy), c(0)
    Line (xx, 0)-(xx, 600), c(0)

    '=====================================================
    'angled wall
    a = (Sin(na * .017453292)) * 200
    b = (Cos(na * .017453292)) * 200
    Line (xx, yy)-(xx + b, yy + a), c(1)
    Line (xx, yy)-(xx - b, yy - a), c(1)

    '=====================================================
    Circle (xx + x, yy - y), 10, c(2) 'point I
    Line (xx, yy)-(xx + x, yy - y), c(2) 'line from origin to point I

    '=====================================================
    nx = Cos(na * (PI / 180)) 'normalize wall angle
    ny = Sin(na * (PI / 180)) 'normalize wall angle

    dx = -x * ny * -1: dy = y * nx: ndp = dx + dy
    'dot product V.N - used to find distance of N
    'The distance of N is from the point of origin to the middle of line A
    'line A is a line from point I to point R (parallel to the angled wall)
    ndpx = Sin(na * (PI / 180)) * ndp
    ndpy = Cos(na * (PI / 180)) * ndp

    '=====================================================
    'calculate point R
    th1 = _Atan2(-y, x) 'radian value of ball (point I)
    th2 = _Atan2(-ndpy, ndpx) 'radian value of line N
    thd = th1 - th2 'find difference
    th3 = th2 - thd 'subtract difference from line N

    rx = Cos(th3) * h: ry = Sin(th3) * h 'point R position - th3 * length of point I to origin
    Circle (xx + rx, yy + ry), 10, c(3) 'point R
    Line (xx, yy)-(xx + rx, yy + ry), c(3) 'origin to point R

    _Display

Loop Until flag = 1