Sinus Render (PB2DLL example)

[kevin]

  Sinus Render (PB2DLL example)

      Attached are two versions of bellow routine compiled to DLL using two different builds of PlayBASIC2DLL.   The routine looks simple enough until you realize there's a square root,  sinus, RGB pack, with multiples and FastDOT pixel plots for every pixel on screen.  The demo defaults to 800*600 resolution, so that's 450 odd thousand iterations, that's a lot of square roots.

      The actual effect is pretty pants, as the focus here has been more on getting the PB2DLL to optimize away as much code as it from common math functions.  Todays build can inline virtually everything from the inner loop bellow and solve it right on the FPU.    These changes make the routine around 3 times faster than when built with yesterdays builds of PB2DLL.   Some of functions like GetDistance2D() bench at up to 15 times faster individually..   Making it quick enough to do a square every pixel.    


     Requires a late PlayBASIC V1.64P beta or higher

PlayBASIC Code: [Select]

 /*
    This function computes the distance between the mouse pointer
    and every pixel on the surface.  The distance is then used as
    as sinus angle to create 'wave'  The result value is drawn as
    dot 
   
*/   


Function DLL_SinusRender()

      Width=GetSurfaceWidth()
      Height=GetSurfaceHeight()
      
      Static BaseAngle#

      midx=mousex()
      midy=mousey()

      lockbuffer
         ThisRGB=point(0,0)
         for ylp=0 to height-1
            for xlp=0 to width-1
               Dist#=BaseAngle#+GetDistance2D(xlp,ylp,midx,midy)         
               Dist=sin(Dist#)*100.0
               fastdot xlp,ylp,Rgb(Dist,Dist,dist)
            next
         next
      lockbuffer
      
      BaseAngle#=mod(BaseAngle#+1.5,3600)

EndFunction

     Hopefully you should be able to see this is pretty naive version of the routine, as a lot of the internal work can be pre-computed out.