Okay, barring any stupid coding problems, here we go with an example. It will only to
two
dimentions right now and it not even complete there, but it provides a starting point:

#declare Max_X = 10; // number of spheres along X Axis
#declare Max_Z = 10; // number of spheres along Y Axis
#declare Base_Radius = 1; // radius of a sphere that is not under the influence
#declare Max_Radius = 2; // radius of the sphere that is under the influence
#declare Steps = 5; // the fifth sphere from the center of the effect will be at Base
Radius

#declare Each_Step = (Max_Radius - Base_Radius)/Steps; // Quick formula to determine

// how different adjacent spheres will be
#declare separation = 4; // the distance between sphere centers


#declare MyGrid = array[Max_X][Max_Z]

// initalize the array, giving everything a value of Base Radius
#macro InitGrid ()
  #declare i = 0;
  #while ( i < Max_X )
    #declare j = 0;
    #while ( j < Max_Z )
      #declare MyGrid[i][j] = Base_Radius;
      #declare j = j + 1;
    #end
    #declare i = i + 1;
  #end
#end


#macro DrawGrid ()
  #declare i = 0;
  #while (i < Max_X )
  #declare j = 0;
    #while ( j < Max_Z )
      sphere { <i*separation,2,j*separation> MyGrid[i][j] // Y value is merely
temporary
               pigment { red 1 }
               finish { phong 1 } }
      #declare j = j + 1;
    #end
    #declare i = i + 1;
  #end
#end

#macro CheckCord(a,b) // we will use this one extensively
  ( (a < Max_X) & (a >= 0) & (b < Max_Z ) & ( b >= 0 ) )
#end

#macro AlterGrid (m,n) // this macro changes the spheres in the gird
  #declare MyGrid[m][n] = Max_Radius;
  #declare cvar = 1;
  #while (cvar < Steps )

    #declare Temp_Radius =  Max_Radius- (cvar * Each_Step );

    #if (CheckCord(m + cvar, n) ) // spheres in the +X direction
      #declare MyGrid[m+cvar][n] = Temp_Radius;
    #end

    #if (CheckCord(m-cvar, n) ) // spheres in the -X direction
      #declare MyGrid[m-cvar][n] = Temp_Radius;
    #end

    #if (CheckCord(m, n+cvar) ) // spheres in the +Z direction
      #declare MyGrid[m][n+cvar] = Temp_Radius;
    #end

    #if (CheckCord(m, n-cvar) ) // spheres in the -Z direction
      #declare MyGrid[m][n-cvar] = Temp_Radius;
    #end

    #if ( CheckCord (m+cvar,n+cvar) ) // spheres in +X,+Z diagonal
      #declare MyGrid[m+cvar][n+cvar] = Temp_Radius;
    #end

    #if ( CheckCord (m+cvar,n-cvar) ) // spheres in the +X,-Z direction
      #declare MyGrid[m+cvar][n-cvar] = Temp_Radius;
    #end

    #if ( CheckCord (m-cvar,n+cvar) ) // spheres in -X,+Z direction
      #declare MyGrid[m-cvar][n+cvar] = Temp_Radius;
    #end

    #if ( CheckCord (m-cvar,n-cvar) ) // spheres in the -X,-Z direction.
      #declare MyGrid[m-cvar][n-cvar] = Temp_Radius;
    #end

    #declare cvar = cvar + 1;
  #end

#end // AlterGrid


InitGrid()

AlterGrid (4,5)

DrawGrid()

Sadly, this still misses 24 cubes in the grid. I'm sure there's an easier way to do
it, and
this is mostly brute force, but it works.


Andrew Cocker wrote:

> I hope someone can help get me started with my latest experiment.
>
> I want to try out arrays. My plan is to create a cube made up of, say, 20x20x20 tiny
> spheres. If I pick one of these spheres and designate it to be the centre of the
effect
> I'm trying to create, and scale it by a factor of 2, how do I make the surrounding
spheres
> get gradually smaller until 5 spheres away they are back to scale 1? I plan to
animate the
> effect so that the centre of the effect moves around inside the array of spheres.
>
> I have heard the term 'fields' used. Is this the method I should use, and if so,
could
> anyone suggest either how it is done, or else point me in the direction of where I
can
> find more out about it.
>
> I am not a mathematician or a programmer, but I hand-code only so I should be able
to make
> use of any suggestions, as long as you assume large levels of ignorance on my part.
>
> Many thanks in anticipation.
>
> -----------
> Andy

Post a reply to this message