REM. Spinmaze: spin the vertical maze to manoeuvre the marble to escape
      REM. v1.0 (C) Richard Russell, http://www.rtrussell.co.uk/, 01-Nov-2024.
      REM. This program is compatible with both BBCSDL & BB4W (plus libraries)
      
      REM!Embed @lib$+"box2dlib", @lib$+"box2ddbg", @lib$+"box2dgfx", @dir$+"bboard.jpg"
      REM!Embed @dir$+"spinmaze.png", @dir$+"spinmaze.dat", @dir$+"marble.png"
      
      MODE 8 : OFF
      MOUSE TO 100,100
      
      title$ = "Spinmaze - Left and Right to spin, Space to restart, D for debug graphics"
      
      INSTALL @lib$+"box2dlib" : PROC_b2Init
      INSTALL @lib$+"box2dgfx"
      IF HIMEM > PAGE + 48000 INSTALL @lib$+"box2ddbg"
      
      IF INKEY$(-256) = "W" THEN
        SYS "SetWindowText", @hwnd%, title$
      ELSE
        SYS "SDL_SetWindowTitle", @hwnd%, title$, @memhdc%
      ENDIF
      
      ON ERROR PROCcleanup : IF ERR=17 CHAIN @lib$+"../examples/tools/touchide" ELSE ERROR 0,REPORT$
      ON CLOSE PROCcleanup : QUIT
      IF INSTR(@usr$, "rtrussell.spinmaze") OR INSTR(@lib$, @dir$) THEN *ESC OFF
      
      gravity_x = 0.0
      gravity_y = -10
      
      myWorld%% = FN_b2CreateWorld(gravity_x, gravity_y)
      PROC_gfxInit(gfx{}, 640, 512, 20)
      IF HIMEM > PAGE + 48000 PROC_b2DebugInit(myWorld%%, %01011, 20)
      
      PROC_gfxLoad(bgnd{}, @dir$+"bboard.jpg", 9.4)
      PROC_gfxLoad(maze{}, @dir$+"spinmaze.png", 20.8)
      PROC_gfxLoad(ball{}, @dir$+"marble.png", 36)
      
      ground%% = FN_b2StaticBox(myWorld%%, 16.0, -4.0, 0.0, 16.0, 0.1)
      
      REM Kinematic body:
      maze%% = FN_b2KinematicBody(myWorld%%, 16.0, 12.8, PI/2, 0.0, 0.0, 0, 0, 0)
      PROC_b2UserDataBody(maze%%, maze{})
      
      REM Rotating maze:
      f% = OPENIN(@dir$ + "spinmaze.dat")
      IF f% = 0 ERROR 100, "Couldn't load spinmaze.dat"
      INPUT #f%, n%
      DIM xc(n%-1), yc(n%-1)
      FOR i% = 0 TO n%-1
        INPUT #f%, xc(i%), yc(i%)
      NEXT
      CLOSE #f%
      edge%% = FN_b2ChainFixture(maze%%, n%, xc(), yc(), 1.0, 0.0, 1.0, TRUE)
      
      REM Dynamic bodies:
      ball%% = FN_b2DynamicBody(myWorld%%, 16.0, 12.8, 0, 0, 0, 0.1, 0, 0)
      mass%% = FN_b2CircleFixture(ball%%, 0.0, 0.0, 0.35, 1.0, 0.0, 1.0)
      PROC_b2UserDataBody(ball%%, ball{})
      PROC_b2SetBullet(ball%%, TRUE)
      
      velIterations% = 6
      posIterations% = 3
      speed = 0
      
      *REFRESH OFF
      IF INKEY$(-256) = "W" SYS "timeGetTime" TO Ticks% ELSE SYS "SDL_GetTicks" TO Ticks%
      REPEAT
        
        PROC_gfxBlit(gfx{}, bgnd{}, 15.9, 12.8, 0)
        PROC_gfxRender(gfx{}, myWorld%%)
        IF INKEY(-51) IF HIMEM > PAGE + 48000 PROC_b2DebugDraw(myWorld%%)
        PROC_gfxDisplay
        
        MOUSE X%, Y%, B%
        CASE TRUE OF
          WHEN INKEY(-122) OR (B% AND 1)<>0 OR (B% AND 4)<>0 AND X% >= 640: speed -= 0.01
          WHEN INKEY(-26)  OR (B% AND 4)<>0: speed += 0.01
          WHEN INKEY(-99): PROC_b2SetBody(ball%%, 16.0, 12.8, 0)
          OTHERWISE: speed /= 1.1
        ENDCASE
        IF ABS(speed) > 1.0 speed = SGN(speed)
        
        IF INKEY$(-256) = "W" SYS "timeGetTime" TO T% ELSE SYS "SDL_GetTicks" TO T%
        WHILE Ticks% < T%
          PROC_b2SetVelocity(maze%%, 0, 0, speed)
          PROC_b2WorldStep(myWorld%%, 0.002, velIterations%, posIterations%)
          Ticks% += 2
        ENDWHILE
        
        IF INKEY$(-256) = "W" WAIT 1
        
      UNTIL FALSE
      PROCcleanup
      END
      
      DEF PROCcleanup
      ON ERROR OFF
      *REFRESH ON
      VDU 23,22,640;500;8,20,16,128
      myWorld%% += 0 : IF myWorld%% PROC_b2DestroyWorld(myWorld%%) : myWorld%% = 0
      IF HIMEM > PAGE + 48000 PROC_b2DebugExit
      PROC_gfxExit
      PROC_b2Exit
      ENDPROC