Plasma Effect

[Clyde]

Here's an experiment with Cobra, which is the plasma routine adapted and featured in the Gravity Dimenisons series. Thanks go to Alan MacDonald for the inspiration with the method.

Code: [Select]

//
// Plasma Effect.
// By Clyde January '07
//
program uses pure2d,keyset

Const
      XRES=640
      YRES=480

Var
      cs:Array[ 3000 ] Of Integer
      sn:Array[ 3000 ] Of Integer
     
      a,c:Real




Procedure InitializePlasma()

  Var a
 
  Begin
     
    For a=0 To 3000
    CS[ a ] = Cos( a )*85
    SN[ a ] = Sin( a )*85
    Next   
 
End


Procedure UpdatePlasma()


  var
    d,b
    red,grn,blu,col
    x,y
 
  //
// Update the plasma movement.
//
  Begin
 
    a = a + 1
  c = c - 2

  If a <   0 Then a=a+360
  If a > 360 Then a=a-360
  If c <   0 Then c=c+360
  If c > 360 Then c=c-360

  d = a
  b = c

    //
  // Draw the plasma effect on the texture.
  //
    For y = 0 To YRES-1
 
      d = d + 4
  b = b + 2
 
      For x = 0 To XRES-1 //Step 2

  Red = Abs(CS[d+x] + SN[y+x] + CS[b])*2
  Grn = Abs(CS[d+x] + SN[y+x] + CS[b])*1
  Blu = Abs(CS[d+x] + SN[y+x] + CS[b])*3
     
        If Red>255 then Red=255
        If Grn>255 then Grn=255
        If blu>255 then Blu=255
     
  Col = ( Red Shl 16) Or ( Grn Shl 8 ) Or ( Blu )

        PixelFast(x,y, Col )
 
  Next
 
    Next
 
 End
//End


Procedure RunPlasma()
 
  Begin
    OpenScreen(XRES,YRES)
   
    While Not KeyDown(VK_Escape)
    Cls
   
      UpdatePlasma()
   
    Flip
    Wend 
   
  End
//End

Begin
  InitializePlasma()
  RunPlasma()
End

I can't judge what the overal speed is with these snippets, as I am using a demo version - which runs in a window, and seems to have debug mode turned on; so it makes for really slow visuals my end. If anyone has the full version of Cobra, I'd be very interested in seeing the results in a full screen application.

Anyhows I hope these prove a bit useful to anyone who is learning ( like myself ), or thinking about looking into Cobra.

Cheers and all the very best,
Clyde.

[mike_g]

Cool  I'll give it a try when I get home. So far I have been lazy with learning Cobra, but I spose leaning C is a bit more of a priority for me at the moment.

[Shockwave]

Nice one Clyde. I'm going to download the demo of Cobra at some point this week so I can run your listings.

[Clyde]

No worries and thanks. Im going to post more up as and when I do them.

The only draw back to the demo version is that, it runs in a window with debug on so they run a tad slow, and there's limited content in the help. It is quite fun dabbling in, and has a nice IDE.

[GrahamK]

He he, glad you like it

Full release is very soon....
Anyway, enough plugging, here is another 'plasma' you may find interesting.
Not as pretty as the one above, but may prove a nice starting point for some demo stuff as it uses the paletted bitmap.

Code: [Select]

program
uses pure2d,keyset

const
  width=640
  height=480

var
 i,x,y : integer
 col:integer
 t1,t2:integer;
begin
     openscreen(width,height)
     for i = 0 to 255
       palette(i,torgba(sin(i*(359.0/255.0))*127+128,sin((i*2)*(359.0/255.0))*127+128,sin((i*3)*(359.0/255.0))*127+128))
     next
       for x = 0 to width-1
         for y = 0 to height-1
           col= ((sin(y+(2*x)))+(sin(x)*4))*127+128
           pixelp(x,y,col mod 256)
         next
       next

     while not keydown(vk_escape)
       t1 = MILLISECS;
       pal2bmp
       shiftpalette(1)
       t2 = MILLISECS;
       text(0,0,'Time:'+(t2-t1))
       flip
     wend
     closescreen
end

interesting thing about paletted mode, is that any image can have one (autocreated first time you write to it using pixelP). So, cheeky demo coders, can use the standard bitmap, and hide values (0-255) behind pixels. Not exactly sure what you could use it for (maybe heightmap info, or maybe 2 4bit offsets for doing warps), but I'm sure people will get creative with it...

[Clyde]

Neat dude 

[Shockwave]

Thanks for the plasma Graham  

Always nice to see demo effects coded in as many languages as possible!

[mike_g]

Just got around to testing these and they both look real nice. Grahams one runs very smoothly too

[Shockwave]

Grahams one is using colour cycling, that's why it's so smooth

I can't honestly say what I think though, the ide looks nice, it's a shame that it's in debug mode.. I might be tempted to write something if I could get a decent turn of speed, or maybe I will soon anyway.

The ability to rotate the palette is very nice.

[GrahamK]

he he, my miggy/c64 roots showing

Sorry about the debug mode, but with making the demo not timeout, It is one of the ways to get people to buy.
I still feel it's reasonably fast in debug mode, certainly enough to evaluate it (which is what the demo is all about after all), but for people to get an idea of the speed without, I'm going to post some of the examples compiled without debug, so people can compare them.

I've been looking at some of the demo's / techniques on your site, and I'm going to add some features which make some of them easier (eg. resetting the alpha channel of a complete image, allowing HSL->RGB conversion etc)... So, I'd be really interested in what people over here do with Cobra

[Shockwave]

Some examples would be great

I'll see if I can make some nice effects in the meantime I can think of at least 30 that can be done with colour cycling!!

[GrahamK]

oooh.. can't wait.

I'm hoping to get a final demo (with the new features) out after the weekend, which I'm hoping will be the same time as it going up for sale!
I've got a nice, voxel demo with movement blur running at a decent rate.

I 'think' I have a bit of trouble with paletted mode inside sprites, but as long as you are just doing image stuff they should be fine.