Lua help needed

[Tiles]

I found a Lua code snippet for bicubic interpolation. Now i want it to use. And am lost. How do i connect this Lua code with my graphic? From which object to work? Is it even possible to use this code snippet from the internet to use with the Lua object so that it resizes a graphic? If so, how?

function get_rgb_cubic_row(x,y,offset)
  local r0,g0,b0, r1,g1,b1, r2,g2,b2, r3,g3,b3
  r0,g0,b0 = get_rgb(x,y)
  r1,g1,b1 = get_rgb(x+1,y)
  r2,g2,b2 = get_rgb(x+2,y)
  r3,g3,b3 = get_rgb(x+3,y)
  return cubic(offset,r0,r1,r2,r3), cubic(offset,g0,g1,g2,g3), cubic(offset,b0,b1,b2,b3)
end

function get_rgb_bicubic (x,y)
  local xi,yi -- integer coordinates
  local dx,dy -- offset from coordinates
  local r,g,b

  xi=math.floor(x)
  yi=math.floor(y)
  dx=x-xi
  dy=y-yi

  r0,g0,b0 = get_rgb_cubic_row(xi-1,yi-1,dx)
  r1,g1,b1 = get_rgb_cubic_row(xi-1,yi,  dx)
  r2,g2,b2 = get_rgb_cubic_row(xi-1,yi+1,dx)
  r3,g3,b3 = get_rgb_cubic_row(xi-1,yi+2,dx)

  return cubic(dy,r0,r1,r2,r3),
         cubic(dy,g0,g1,g2,g3),
         cubic(dy,b0,b1,b2,b3)
end

function scale(ratio)
  for y=0, height-1 do
    for x=0, width-1 do
      -- calculate the source coordinates (u,v)
      u = x * (1.0/ratio)
      v = y * (1.0/ratio)
      r,g,b=get_rgb_bicubic(u,v)
      set_rgb(x,y,r,g,b)
    end
    progress (y/height)
  end
  flush()
end

function cubic(offset,v0,v1,v2,v3)
  -- offset is the offset of the sampled value between v1 and v2
   return   (((( -7 * v0 + 21 * v1 - 21 * v2 + 7 * v3 ) * offset +
               ( 15 * v0 - 36 * v1 + 27 * v2 - 6 * v3 ) ) * offset +
               ( -9 * v0 + 9 * v2 ) ) * offset + (v0 + 16 * v1 + v2) ) / 18.0;
end

scale(3)

[Joshtek]

Quick and messy implementation proof of concept: http://x.jflom.com/files/klik/interpolation.mfa

[Tiles]

Amazing. Works like charm. This teaches me also alot about LUA. Very useful. Many thanks

[Tiles]

Hmm, there is a functioncall when clicking the button. And here you can set the scale factor, right? Call Function scale with 7 with 0 result.

Increasing the number 7 leads to a greater scaled result. But i cannot enter a counter value here nor a string from a value. Only choice is to change the value in the expression itself. Which i cannot do at runtime.

How can i influence the scalefactor at runtime?

[Joshtek]

In the Call Function expression replace 7 with str$(value( "Counter" ))

[Tiles]

Ah that's strange. I could have sworn that i had tried this before ... :whistle:

Works. Many thanks

[Joshtek]

If you get it working well then please post your progress.

[Tiles]

Progress is so far that i have implemented the counter now. Not really worth posting it

Well, it works like charm, but is unfortunately unbelievable slow because it works with fastloop and Overlay. I would need it to resize to 512 three times at once( the perlin noise layers) and to 4096 or even to 8192 in the maximum case. Which needs several minutes then. I need around 2 minutes for resizing a single picture to 512. And my PC is a dual core one. That's simply too much. Even when i get out the best quality :/

And that's why i cannot use it. I cannot bother my users with enough free time to go shopping just to resize a picture :grin:

The example is not worthless though. I enjoy studying it. Trying to understand what's going on. Is a great example what can be done with LUA. Again many thanks for this

[James]

MMF2 doesn't use both cores anyway.

[neat_Kliker2]

MMF2 doesn't use both cores anyway.

AFAIK the only real game that does is supreme commander, server apps do as well