layout a_blocks_BCA

code metapost

initsymbol ("a_blocks_BCA");

def a_blocks_BCA (expr p) =
 T:=identity;
% This is probably a better way to impliment the different sided blocks calculates the vertices of polygons
%for (i = 0; i < n; i++) {
% printf("%f %f\n",x + r * Math.cos(2 * Math.PI * i / n), y + r * Math.sin(2 * Math.PI * i / n));
%}

boolean overlap;
overlap:=
if known ATTR_overlap: scantokens(ATTR_overlap)
else: false fi;

% Proportion to the size of separation of centres of the blocks as set out in a rectangular grid
%FIXME: Really need to check if it is number and not zero in for some cases
separation:= 
if known ATTR_separation: scantokens(ATTR_separation)
else: 0.7 fi;

% Max each point of the base block can be moved. Too big and they can intersect themselves
block_random:=
if known ATTR_block_random: scantokens(ATTR_block_random);
else: 0.7
fi;

% Rotation from 0 of base block, can be used to set all blocks to the same angle
base_rotation:=
if known ATTR_base_rotation: scantokens(ATTR_base_rotation)
else: 0
fi;

% Rotation either side of base rotation eg 20 will be plus or minus 10 each side

random_rotation:=
if known ATTR_random_rotation: scantokens(ATTR_random_rotation)
else: 360
fi;

% Minimum multiplier used for the base shape

min_scale_factor:=
if known ATTR_min_size: scantokens(ATTR_min_size)
else: 0.7
fi;

% Added to the minimum multiplier to get the maximum scale
add_scale_factor:=
if known ATTR_max_size: scantokens(ATTR_max_size)
else: 0.6
fi;

% How much longer the block is than it is wide, before randomising
aspect:=
if known ATTR_aspect: scantokens(ATTR_aspect)
else: 1.5
fi;

% Max random amount block can be moved from the original grid
shift_random:=
if known ATTR_shift_random: scantokens(ATTR_shift_random)
else: 0.75
fi;

% Set the propotions of different sided block
if known ATTR_shapes:
b_tri:=scantokens substring (0,1) of ATTR_shapes;
b_quad:=scantokens substring (2,3) of ATTR_shapes;
b_pent:=scantokens substring (4,5) of ATTR_shapes;
b_hex:=scantokens substring (6,7) of ATTR_shapes;
else:
b_tri:=1;
b_quad:=3;
b_pent:=4;
b_hex:=2;
fi;

pickup PenC;
path q, qq; q = bbox p;
pair outside;
outside:= ulcorner q + up;
picture tmp_pic; 
uu := max(u, (xpart urcorner q - xpart llcorner q)/100, (ypart urcorner q - ypart     llcorner q)/100);
iu := uu * aspect;
blocks := b_tri+b_quad + b_pent + b_hex;
tmp_pic := image(
   for i = xpart llcorner q step separation * aspect * uu until xpart urcorner q:
      for j = ypart llcorner q step separation*uu until ypart urcorner q:
        pick_sides := uniformdeviate(blocks);
        if pick_sides < b_tri:
          qq := punked (((.5iu,0)--(-0.25iu,.43uu)--(-.25iu,-0.43uu)--cycle) 
          randomized (block_random * uu))
          scaled (uniformdeviate(add_scale_factor)+min_scale_factor)
         rotated (base_rotation + random_rotation / 2 - uniformdeviate(random_rotation) )
          shifted ((i,j) randomized (shift_random * uu));
        elseif pick_sides < b_tri + b_quad:
                    qq := punked (((0.5iu,0)--(0,0.5uu)--(-0.5iu,0)--(0,-0.5uu)--cycle) 
          randomized (block_random * uu))
          scaled (uniformdeviate(add_scale_factor)+min_scale_factor)
         rotated (base_rotation + random_rotation / 2 - uniformdeviate(random_rotation) )
          shifted ((i,j) randomized (shift_random * uu));
         elseif pick_sides < b_tri + b_quad + b_pent:
                    qq := punked (((0.5iu,0)--(.15iu,0.48uu)--(-0.4iu,0.29uu)--(-0.4iu,-0.29uu)--(0.15iu,-0.48uu)--cycle) 
          randomized (block_random * uu))
          scaled (uniformdeviate(add_scale_factor)+min_scale_factor)
         rotated (base_rotation + random_rotation / 2 - uniformdeviate(random_rotation) )
          shifted ((i,j) randomized (shift_random * uu));
          else:
          qq := punked (((0.5iu,0)--(0.25iu,0.43uu)--(-0.25iu,0.43uu)--(-0.5iu,0)--(-0.25iu,-0.43uu)--(0.25iu,-0.43uu)--cycle) 
          randomized (block_random * uu))
          scaled (uniformdeviate(add_scale_factor)+min_scale_factor)
          rotated (base_rotation + random_rotation / 2 - uniformdeviate(random_rotation) )
          shifted ((i,j) randomized (shift_random * uu));
         fi;
       if not overlap: 
          forever: % Repeatedly reduces the size of the image, as this is done round zero it also moves it to the zero location, until it fits in the area
           exitif xpart (p intersectiontimes qq) < 0;
           qq:= qq scaled (0.99 );
          endfor;
        fi
            if pointinside((i,j),p,outside):
               thclean qq;
               thdraw qq;
             fi;
      endfor;  
   endfor;
);
 % clip tmp_pic to p; %this appears not to be needed as the pointinside removes any outside the area
 drawoptions(); % no idea what this does!
 draw tmp_pic;
enddef; 

endcode

endlayout