Option explicit
Option default none
Option console serial
MODE 2
FRAMEBUFFER create
FRAMEBUFFER write f
CLS

'brownian motion demo using sprites with static object collisions
Dim integer x(64),y(64),c(64)
Dim float direction(64)
Dim integer i,j,k, collision=0
Dim string q$

' Create the atom sprites
For i=1 To 64
 direction(i)=Rnd*360 'establish the starting direction for each atom
 c(i)=RGB(Rnd*255,Rnd*255,Rnd*255) 'give each atom a colour
 Circle 10,10,4,1,,RGB(white),c(i) 'draw the atom
 Sprite read i,6,6,9,9 'read it in as a sprite
Next i
CLS rgb(myrtle)

' Load background image (pick something 320x240)
'Load jpg "b:/img320"

' Draw screen border
Box 0,0,MM.HRES,MM.VRES

' Draw red obstacle boxes and define them as static objects
' Box 1 - top left area
Box 60,40,50,50,3,RGB(red),RGB(red)
Sprite static 1, 60, 40, 50, 50

' Box 2 - top right area  
Box 210,40,50,50,3,RGB(red),RGB(red)
Sprite static 2, 210, 40, 50, 50

' Box 3 - center
Box 135,95,50,50,3,RGB(red),RGB(red)
Sprite static 3, 135, 95, 50, 50

' Box 4 - bottom left area
Box 60,150,50,50,3,RGB(red),RGB(red)
Sprite static 4, 60, 150, 50, 50

' Box 5 - bottom right area
Box 210,150,50,50,3,RGB(red),RGB(red)
Sprite static 5, 210, 150, 50, 50

' Place the atoms on screen
k=1
For i=MM.HRES\9 To MM.HRES\9*8 Step MM.HRES\9
 For j=MM.VRES\9 To MM.VRES\9*8 Step MM.VRES\9
   ' Skip positions that would overlap with boxes
   If Not inside_box(i, j, 9) Then
     Sprite show k,i,j,1
     x(k)=i
     y(k)=j
     vector k,direction(k), 0, x(k), y(k) 'load up the vector move
   Else
     ' Find a random valid position that doesn't overlap boxes
     Do
       x(k) = Rnd*(MM.HRES-9)
       y(k) = Rnd*(MM.VRES-9)
     Loop Until Not inside_box(x(k), y(k), 9)
     Sprite show k,x(k),y(k),1
     vector k,direction(k), 0, x(k), y(k)
   EndIf
   k=k+1
 Next j
Next i

' Main animation loop
Do
 For i=1 To 64
   vector i, direction(i), 1, x(i), y(i)
   Sprite show i,x(i),y(i),1
   ' Check for sprite collisions OR background object collisions
   If sprite(S,i)<>-1 Then
     break_collision i
   EndIf
 Next i

 FRAMEBUFFER copy f,n
 Print Timer
 Timer = 0
Loop

' Check if a position is inside any of the static boxes
Function inside_box(px As integer, py As integer, size As integer) As integer
 Local integer b
 For b = 1 To 5
   If Sprite(ST, b, A) Then  ' If static object is active
     If px + size > Sprite(ST, b, X) And px < Sprite(ST, b, X) + Sprite(ST, b, W) Then
       If py + size > Sprite(ST, b, Y) And py < Sprite(ST, b, Y) + Sprite(ST, b, H) Then
         inside_box = 1
         Exit Function
       EndIf
     EndIf
   EndIf
 Next b
 inside_box = 0
End Function

' Vector movement subroutine
Sub vector(myobj As integer, angle As float, distance As float, x_new As integer, y_new As integer)
 Static float y_move(64), x_move(64)
 Static float x_last(69), y_last(64)
 Static float last_angle(64)
 
 If distance=0 Then
   x_last(myobj)=x_new
   y_last(myobj)=y_new
 EndIf
 If angle<>last_angle(myobj) Then
   y_move(myobj)=-Cos(Rad(angle))
   x_move(myobj)=Sin(Rad(angle))
   last_angle(myobj)=angle
 EndIf
 x_last(myobj) = x_last(myobj) + distance * x_move(myobj)
 y_last(myobj) = y_last(myobj) + distance * y_move(myobj)
 x_new=Cint(x_last(myobj))
 y_new=Cint(y_last(myobj))
End Sub

' Handle collisions - break them by bouncing
Sub break_collision(atom As integer)
 Local integer j=1, col, bg_hit, hit
 Local integer bx, by, bw, bh, ax, ay
 Local float current_angle=direction(atom)
 Local float dx, dy
 
 ' Check what type of collision occurred
 If sprite(e,atom)=1 Then
   ' Collision with left of screen
   current_angle=360-current_angle
 ElseIf sprite(e,atom)=2 Then
   ' Collision with top of screen
   current_angle=((540-current_angle) Mod 360)
 ElseIf sprite(e,atom)=4 Then
   ' Collision with right of screen
   current_angle=360-current_angle
 ElseIf sprite(e,atom)=8 Then
   ' Collision with bottom of screen
   current_angle=((540-current_angle) Mod 360)
 Else
   ' Check for static object collision
   bg_hit = 0
   For col = 1 To Sprite(C, atom)
     hit = Sprite(C, atom, col)
     If hit >= &H80 And hit < &HF0 Then
       ' Static object collision (codes 0x80-0xBF)
       bg_hit = hit And &H3F  ' Extract object number
       Exit For
     EndIf
   Next col
   
   If bg_hit > 0 Then
     ' Bounce off static object - determine which side was hit
     bx = Sprite(ST, bg_hit, X)
     by = Sprite(ST, bg_hit, Y)
     bw = Sprite(ST, bg_hit, W)
     bh = Sprite(ST, bg_hit, H)
     ax = x(atom) + Sprite(W, atom)\2
     ay = y(atom) + Sprite(H, atom)\2
     
     ' Determine if collision is more horizontal or vertical
     dx = Abs(ax - (bx + bw\2))
     dy = Abs(ay - (by + bh\2))
     
     If dx / bw > dy / bh Then
       ' Horizontal bounce (hit left or right side)
       current_angle = 360 - current_angle
     Else
       ' Vertical bounce (hit top or bottom)
       current_angle = ((540 - current_angle) Mod 360)
     EndIf
   Else
     ' Collision with another sprite or corner
     current_angle = current_angle + 180
   EndIf
 EndIf
 
 direction(atom) = current_angle
 vector atom, direction(atom), j, x(atom), y(atom) 'break the collision
 Sprite show atom, x(atom), y(atom), 1
 
 ' If the simple bounce didn't work, try a random bounce
 Do While (sprite(t,atom) Or sprite(e,atom)) And j<10
   Do
     direction(atom) = Rnd*360
     vector atom, direction(atom), j, x(atom), y(atom)
     j = j + 1
   Loop Until x(atom)>=0 And x(atom)<=MM.HRES-sprite(w,atom) And y(atom)>=0 And y(atom)<=MM.VRES-sprite(h,atom)
   Sprite show atom, x(atom), y(atom), 1
 Loop
 
 ' If that didn't work then place the atom randomly (avoiding boxes)
 Do While (sprite(t,atom) Or sprite(e,atom))
   direction(atom) = Rnd*360
   Do
     x(atom) = Rnd*(MM.HRES-sprite(w,atom))
     y(atom) = Rnd*(MM.VRES-sprite(h,atom))
   Loop Until Not inside_box(x(atom), y(atom), sprite(w,atom))
   vector atom, direction(atom), 0, x(atom), y(atom)
   Sprite show atom, x(atom), y(atom), 1
 Loop
End Sub

x15%=sprite(b,(n\3) mode 5+1,3)