Parallax - Printable Version

Code:
'====================================================

' PARALLAX AUTO-SCROLL DEMO v2 - 3 minute cycle

' - blinking stars (sin-driven alpha twinkle)

' - moon drawn with draw ellipse + glow halo

' - mountain silhouettes from sin() contours

' - treeline & trees with varied heights

'====================================================



set window "Parallax Demo", 384, 224, false, 2

set redraw off



constant SCROLL_SPEED = 90.0    ' camera pixels per frame

constant WORLD_W = 1535.0       ' one-way travel distance

visible CYCLE = 4 * WORLD_W / SCROLL_SPEED  ' = 180 seconds

constant GROUND_Y = 180



visible cam = [] ; cam.x = 0



' --- Build foreground trees with VARIED sizes (once, at startup) ---

' Deterministic per run. Add "randomize time()" above for a new forest each run.

visible trees = [] ; trees.num = 0

for i = 0 to 9

    trees[i] = []

    trees[i].x = i * 100 + rnd(0, 60)   ' scattered across world 0..960

    trees[i].w = 14 + rnd(0, 16)        ' width  varies 14-30

    trees[i].h = 28 + rnd(0, 38)        ' height varies 28-66

next

trees.num = 10



' ================= MAIN LOOP =================

do



    ' --- AUTO-SCROLL CAMERA (triangle wave / ping-pong) ---

    ' phase 0..0.5 : camera moves RIGHT  (0 -> WORLD_W)

    ' phase 0.5..1 : camera moves LEFT   (WORLD_W -> 0)

    t = (clock() / 1000) % CYCLE

    phase = t / CYCLE

    if phase < 0.5 then

        cam.x = WORLD_W * (phase * 2)

    else

        cam.x = WORLD_W * (2 - phase * 2)

    endif



    ' ==================== DRAWING ====================



    ' LAYER 0: Night sky (fixed, depth 0 - never moves)

    set color 10, 10, 30; draw rect 0, 0, 384, 224, true



    ' LAYER 1: BLINKING STARS (depth 0.5, wrapped with %)

    ' Alpha oscillates via sin(); each star gets its own phase offset

    ' so they twinkle independently instead of pulsing in sync

    tw = clock() / 500

    for s = 0 to 5

        alpha = int(128 + 127 * sin(tw + s * 1.7))

        set color 255, 255, 255, alpha

        sx = int((150 + s * 73 - cam.x * 0.5) % 440)

        sy = 14 + (s * 29) % 70      ' deterministic y scatter

        sz = 2 + s % 2               ' sizes alternate 2px / 3px

        draw rect sx, sy, sz, sz, true

    next

    set color 255, 255, 255, 255     ' restore full opacity



    ' LAYER 2: MOON with soft glow (depth 0.1, now draw ellipse)

    moonX = int(300 - cam.x * 0.1)

    set color 200, 200, 255, 40

    draw ellipse moonX, 60, 26, 26, true    ' faint glow halo

    set color 200, 200, 255

    draw ellipse moonX, 60, 16, 16, true    ' moon body

    set color 170, 170, 225

    draw ellipse moonX - 5, 56, 4, 4, true  ' craters

    draw ellipse moonX + 6, 64, 3, 3, true



    ' LAYER 3: MOUNTAIN SILHOUETTES via sin() contours (depth 0.2)

    ' made of TWO blended sine frequencies = natural mountain outline

    set color 40, 40, 60

    for mx = 0 to 384 

        wx = mx + cam.x * 0.2                ' world x under this column

        mh = 70 + 45 * sin(wx / 45) + 18 * sin(wx / 19)

        draw rect mx, int(GROUND_Y - mh), 7, int(mh), true

    next



    ' LAYER 4: TREELINE with varying canopy heights (depth 0.5)

    ' Same slicing trick, higher frequencies = bumpy treetops

    set color 30, 50, 30

    for tx = 0 to 384 

        wx = tx + cam.x * 0.5

        th = 28 + 14 * sin(wx / 23) + 9 * sin(wx / 11 + 1)

        draw rect tx, int(GROUND_Y - th), 11, int(th), true

    next



    ' LAYER 5: FOREGROUND TREES, varied sizes (depth 0.8)

    ' Precomputed table + tiled copies every 1000px = infinite forest

    set color 20, 30, 20

    for j = -1 to 1

        for i = 0 to trees.num - 1

            fx = int(trees[i].x + j * 1000 - cam.x * 0.8)

            if fx > -80 and fx < 460 then

                draw rect fx, GROUND_Y - trees[i].h, trees[i].w, trees[i].h, true

            endif

        next

    next



    ' LAYER 6: Ground = player layer (depth 1.0 - "real" world)

    set color 60, 40, 20; draw rect int(-cam.x), GROUND_Y, 1500, 50, true



    ' cycle timer proof

    set color 255, 255, 255

    set caret 8, 8

    'wln "Cycle : " + str(int(t)) + " / " + str(int(CYCLE)) + " sec"

    wln "cam.x : " + str(int(cam.x))

    wln "ESC to quit"



    redraw

    fwait 60

until keydown(KEY_ESCAPE)