Rotating blurry thing (BB4W + GfxLib)

[David Williams]

Here's a little blast from the past which I've just rediscovered hiding on a hard drive:

http://www.proggies.uk/gfxlibdemos/prog ... wdx9fs.zip

It's probably best to extract the EXE file from the zip folder before running, or your Windows/AV combination might refuse to run it.

Click mouse to exit.

[p_m21987]

To be honest I don't see the point of posting these things here if you're not including the source code.

[RichardRussell]

To be honest I don't see the point of posting these things here if you're not including the source code.

I have some sympathy with that viewpoint, but in the case of such a simple example isn't there perhaps just as much interest and challenge in reproducing something similar from scratch without having somebody else's source code to copy? It took me no more than ten minutes to create this (admittedly poor in comparison with David's) BBCSDL version; it may be tricky to improve on it greatly given SDL's 8-bit alpha resolution.

Code: Select all

      SYS "SDL_SetWindowFullscreen", @hwnd%, &1001
      VDU 26
      IF POS REM SDL thread sync
      WinW% = @vdu%!208
      WinH% = @vdu%!212

      DIM Dst{x%, y%, w%, h%}
      tex%% = FNloadtexture(@dir$ + "BBCSDL_spectrum.png")
      SYS "SDL_SetTextureBlendMode", tex%%, 1
      SYS "SDL_SetTextureAlphaMod", tex%%, 8

      REPEAT
        angle# = 360*SIN(TIME/1100)
        scale = 1 + 3.0 * ABSSIN(TIME/200)
        Dst.w% = WinW% * scale
        Dst.h% = WinW% * scale
        Dst.x% = (WinW% - Dst.w%) DIV 2
        Dst.y% = (WinH% - Dst.h%) DIV 2
        IF @platform% AND &40 THEN
          IF angle#=0 ?(^angle#+7)=&80
          SYS "SDL_RenderCopyEx", @memhdc%, tex%%, FALSE, Dst{}, angle#, FALSE, FALSE
        ELSE
          SYS "SDL_RenderCopyEx", @memhdc%, tex%%, FALSE, Dst{}, !^angle#, !(^angle#+4), FALSE, FALSE
        ENDIF
        *REFRESH
        MOUSE X%, Y%, B%
      UNTIL B% OR INKEY(0) <> -1
      QUIT

      DEF FNloadtexture(file$)
      LOCAL s%%, t%%
      SYS "STBIMG_Load", file$ TO s%%
      IF @platform% AND &40 ELSE s%% = !^s%%
      IF s%%=0 ERROR 104, "Unable to load image: " + file$
      SYS "SDL_CreateTextureFromSurface", @memhdc%, s%% TO t%%
      IF @platform% AND &40 ELSE t%% = !^t%%
      IF t%%=0 ERROR 105, "Unable to create texture: " + file$
      SYS "SDL_FreeSurface", s%%
      = t%%

The image it uses is attached.

[David Williams]

To be honest I don't see the point of posting these things here if you're not including the source code.

Fair point. Here's the source code:

http://www.proggies.uk/temp/blurry_src.zip

I had to tidy up the program a bit and make some modifications so that it actually worked (it relied on a library file that was no longer compatible), which is probably why I didn't include the source in the first place.

[David Williams]

It took me no more than ten minutes to create this (admittedly poor in comparison with David's) BBCSDL version; it may be tricky to improve on it greatly given SDL's 8-bit alpha resolution.

You have to take full much credit for those nice smooth colour gradients on display with my version, because It relies on your excellent PlotRotateScaleBilinear routine to achieve the effect.

[RichardRussell]

It relies on your excellent PlotRotateScaleBilinear routine to achieve the effect.

To enable bilinear filtering in the BBCSDL version modify the code as follows, it does reduce the 'pixellation':

Code: Select all

      SYS "SDL_SetHint", "SDL_RENDER_SCALE_QUALITY", "linear"
      tex%% = FNloadtexture(@dir$ + "BBCSDL_spectrum.png")

[Repton]

Gaudi probably thought the same thing when he built the Sagrada familiar without any plans. People talk about not reinventing the wheel in coding but this is more like reverse engineering. There are many compiled programs where the source code is lost or like Fermat last theorem when the apparent solution is also lost. The rosetta code is full of these reinventions.

[RichardRussell]

isn't there perhaps just as much interest and challenge in reproducing something similar from scratch without having somebody else's source code to copy?

Click here to run this program in your browser (Chrome, Edge or Firefox)!