Swirling QB64 drainpipe. Another rotozoom effect.

[Dav]

I keep playing around with the fascinating rotozoom.  Here's an effect I thought may be worth sharing.  Tried _SETALPHA on the _DISPLAY which seems to add a blur effect on the swirl.  Let it run a bit for interesting colors.

- Dav

Code: QB64: [Select]

1.  
2. SCREEN _NEWIMAGE(800, 640, 32)
3.  
4. DO
5.     _SETALPHA RND * 254, , -11: s = RND * 125
6.     _PUTIMAGE (RND * _WIDTH, RND * _HEIGHT)-STEP(s, s), -11
7.     _SETALPHA RND * 255, 1 TO -1, _DISPLAY
8.     RotoZoom3 _WIDTH / 2 + RND * 3, _HEIGHT / 2 + RND * 3, _DISPLAY, .88, .98, _D2R(a): a = a + 1
9.     _LIMIT 25
10. LOOP UNTIL INKEY$ <> ""
11.  
12.  
13. SUB RotoZoom3 (X AS LONG, Y AS LONG, Image AS LONG, xScale AS SINGLE, yScale AS SINGLE, radianRotation AS SINGLE)
14.     DIM px(3) AS SINGLE: DIM py(3) AS SINGLE ' simple arrays for x, y to hold the 4 corners of image
15.     DIM W&, H&, sinr!, cosr!, i&, x2&, y2& '   variables for image manipulation
16.     W& = _WIDTH(Image&): H& = _HEIGHT(Image&)
17.     px(0) = -W& / 2: py(0) = -H& / 2 'left top corner
18.     px(1) = -W& / 2: py(1) = H& / 2 ' left bottom corner
19.     px(2) = W& / 2: py(2) = H& / 2 '  right bottom
20.     px(3) = W& / 2: py(3) = -H& / 2 ' right top
21.     sinr! = SIN(-radianRotation): cosr! = COS(-radianRotation) ' rotation helpers
22.     FOR i& = 0 TO 3 ' calc new point locations with rotation and zoom
23.         x2& = xScale * (px(i&) * cosr! + sinr! * py(i&)) + X: y2& = yScale * (py(i&) * cosr! - px(i&) * sinr!) + Y
24.         px(i&) = x2&: py(i&) = y2&
25.     NEXT
26.     _MAPTRIANGLE _SEAMLESS(0, 0)-(0, H& - 1)-(W& - 1, H& - 1), Image TO(px(0), py(0))-(px(1), py(1))-(px(2), py(2))
27.     _MAPTRIANGLE _SEAMLESS(0, 0)-(W& - 1, 0)-(W& - 1, H& - 1), Image TO(px(0), py(0))-(px(3), py(3))-(px(2), py(2))
28. END SUB
29.  
30.  

[Pete]

No! No! No! You need the FreeBASIC icon for that!

Well, help me out here. What part of the code picks up the QB64 icon from the title window?

Pete

[Dav]

I should not make a habit of posting code that uses it, but -11 is the image handle currently for the builtin icon.. I use at home frequently when experimentig, but its not a good idea to share code using i guess. Sorry about that.

- Dav

[Pete]

What's the number for the not-built in FB horse? That's what I want to see swirling around!

Thanks Dav, I had no idea about the -11 being reserved for the QB64 icon. That's useful!

Pete

[bplus]

@Dav you should get even more effects by using the x and y scale independently.

[johnno56]

Just tried this demo... Cool... Not very accurate... but cool none the less.

Let me explain... For those of us that live "down under" the swirl (coriolis effect) is correct... Should this be moving in the opposite direction for those of us that live above the equator? Oh. I can be SO picky at times... (bplus... not a word... lol)

[Pete]

🙃

[johnno56]

Oh. Ha Ha... Good one, Pete.