Hi. Im trying to code a macro that creates a heightfield uning some sort of
recursive algorithm. I've searched the internet for a suitable algorithm
that I could convert to SDL (suitable=simple enough for me to understand).
A came across something named the Diamond-Square Algorithm (aka Midpoint
Displacement Algorithm). I got the general idea of the algorithm and
started to convert it to the SDL. I now have a file containing the code,
its still not finished, it is very inefficient, but I think the main things
are done.
The problem is...it doesnt work.

Here's the code:



//BEGIN CODE

#macro tilenum(num)

#while (num<0 & num>Size)
#if(num>Size)
(num-Size)
#end
#if(num<Size)
(num+Size)
#end
#end

#end


#macro Diamond(Sub_Size,Point_X,Point_Z)
#declare Array[Point_X][Point_Z]=(

(Array[tilenum(Point_X-(Sub_Size/2))][tilenum(Point_Z-(Sub_Size/2))])+

(Array[tilenum(Point_X+(Sub_Size/2))][tilenum(Point_Z-(Sub_Size/2))])+

(Array[tilenum(Point_X+(Sub_Size/2))][tilenum(Point_Z+(Sub_Size/2))])+

(Array[tilenum(Point_X-(Sub_Size/2))][tilenum(Point_Z+(Sub_Size/2))])

)

/4+

(rand(Rand)*(RandVal*2)-RandVal);

#end


#macro Square(Sub_Size,Point_X,Point_Z)
#declare Array[Point_X][Point_Z]=(

(Array[Point_X][tilenum(Point_Z-(Sub_Size/2))])+

(Array[tilenum(Point_X+(Sub_Size/2))][Point_Z])+

(Array[Point_X][tilenum(Point_Z-(Sub_Size/2))])+

(Array[tilenum(Point_X-(Sub_Size/2))][Point_Z])

)

/4+

(rand(Rand)*(RandVal*2)-RandVal);

#end


#macro MainLoop(Sub_Size)

#declare N1=0;
#declare N2=0;
#while (N2<Size)

#declare D_X=N1+(Sub_Size/2);
#declare D_Z=N2+(Sub_Size/2);

Diamond(Sub_Size,D_X,D_Z)

Square(Sub_Size,D_X,D_Z-(Sub_Size/2))
Square(Sub_Size,D_X+(Sub_Size/2),D_Z)
Square(Sub_Size,D_X,D_Z+(Sub_Size/2))
Square(Sub_Size,D_X-(Sub_Size/2),D_Z)


#declare N1=N1+Sub_Size;
#if (N1>=Size)
#declare N1=0;
#declare N2=N2+Sub_Size;
#end
#end


#declare RandVal=RandVal/2;
#declare Int_Val=Int_Val+1;
#if(Int_Val<=Int)
MainLoop(Sub_Size/2)
#end

#end


#macro FractalTerrain(Size,BaseHeight,Seed,Int,RandVal)

#declare Array=array[Size+1][Size+1]

#declare Array[0][0]=BaseHeight;
#declare Array[0][Size]=BaseHeight;
#declare Array[Size][0]=BaseHeight;
#declare Array[Size][Size]=BaseHeight;
#declare Rand=seed(Seed);
#declare Size=Size;
#declare RandVal=RandVal;

#declare Int=0;
MainLoop(Size)

#end

FractalTerrain(4,1,1,2,1)

//END CODE



I get the error "Parse Error: Expected 'numeric expression', ] found
instead"
Cant you use a macro when reffering to arrays?
Any comment on this would be appreciated.


Oh, I almost forgot to thank Thorsten, Shay and Mike for the help with the
"function macro" (long time ago).
It turned out quite good, thanks.


/The Ugly

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