Square, diamond, square, diamond

Given a non-empty string of lowercase ASCII letters a-z, take its first character, and:

• Surround it with a square of copies of the second character,
• Surround that with a diamond of copies of the third character,
• Surround that with a square of copies of the fourth character…

…alternating between square and diamond borders until the end of the string. Empty space between the borders should be represented by ASCII spaces ().

To add a square border, draw a square exactly around the entire current “working array”:

                                               sssssssssss
t              s    t    s
t t             s   t t   s
t   t            s  t   t  s
t aaa t           s t aaa t s
t  aca  t    =>    st  aca  ts
t aaa t           s t aaa t s
t   t            s  t   t  s
t t             s   t t   s
t              s    t    s
sssssssssss


To add a diamond border, draw a centered diamond shape that touches the outermost square diagonally, but not orthogonally:

                                                     s
s s
s   s
s     s
s       s
s         s
s           s
wwwwwwwwwww               s wwwwwwwwwww s
w    o    w              s  w    o    w  s
w   o o   w             s   w   o o   w   s
w  o   o  w            s    w  o   o  w    s
w o eee o w           s     w o eee o w     s
wo  eme  ow    =>    s      wo  eme  ow      s
w o eee o w           s     w o eee o w     s
w  o   o  w            s    w  o   o  w    s
w   o o   w             s   w   o o   w   s
w    o    w              s  w    o    w  s
wwwwwwwwwww               s wwwwwwwwwww s
s           s
s         s
s       s
s     s
s   s
s s
s


Your program must output the final array.

• Each line may contain any amount of trailing spaces.
• You may output a list of strings representing lines, or a single newline-separated string with an optional trailing newline.
• Leading/trailing blank lines are disallowed.
• Leading columns of spaces are also disallowed.

This is . The shortest code in bytes wins.

Test cases

The above examples are expected outputs for cat, cats, meow, and meows, in reading order. Some other cases worth handling:

• For the input a, your program should output:

a

• For the input ab, your program should output:

bbb
bab
bbb

• For the input codegolf, your program should output:

fffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
f                            l                            f
f                           l l                           f
f                          l   l                          f
f                         l     l                         f
f                        l       l                        f
f                       l         l                       f
f                      l           l                      f
f                     l             l                     f
f                    l               l                    f
f                   l                 l                   f
f                  l                   l                  f
f                 l                     l                 f
f                l                       l                f
f               l                         l               f
f              l                           l              f
f             l ooooooooooooooooooooooooooo l             f
f            l  o            g            o  l            f
f           l   o           g g           o   l           f
f          l    o          g   g          o    l          f
f         l     o         g     g         o     l         f
f        l      o        g       g        o      l        f
f       l       o       g         g       o       l       f
f      l        o      g           g      o        l      f
f     l         o     g eeeeeeeeeee g     o         l     f
f    l          o    g  e    d    e  g    o          l    f
f   l           o   g   e   d d   e   g   o           l   f
f  l            o  g    e  d   d  e    g  o            l  f
f l             o g     e d ooo d e     g o             l f
fl              og      ed  oco  de      go              lf
f l             o g     e d ooo d e     g o             l f
f  l            o  g    e  d   d  e    g  o            l  f
f   l           o   g   e   d d   e   g   o           l   f
f    l          o    g  e    d    e  g    o          l    f
f     l         o     g eeeeeeeeeee g     o         l     f
f      l        o      g           g      o        l      f
f       l       o       g         g       o       l       f
f        l      o        g       g        o      l        f
f         l     o         g     g         o     l         f
f          l    o          g   g          o    l          f
f           l   o           g g           o   l           f
f            l  o            g            o  l            f
f             l ooooooooooooooooooooooooooo l             f
f              l                           l              f
f               l                         l               f
f                l                       l                f
f                 l                     l                 f
f                  l                   l                  f
f                   l                 l                   f
f                    l               l                    f
f                     l             l                     f
f                      l           l                      f
f                       l         l                       f
f                        l       l                        f
f                         l     l                         f
f                          l   l                          f
f                           l l                           f
f                            l                            f
fffffffffffffffffffffffffffffffffffffffffffffffffffffffffff


Reference implementation

I wrote some Julia code that your program’s output should match (at least visually). Try it online!

MATL, 63 54 bytes

l&)"X@o?TT@I$Ya}t&n2/Xkw2+-|thYa9Mqt_w&:|&+tleXM=@*+]c  Try it Online! Explanation  % Implicitly grab the input as a string l&) % Separate the first letter from the rest and push them onto the stack " % For every letter in the string besides the first X@o? % If this is an odd iteration through the loop TT % Push the array [1, 1] @ % Get current character I$Ya    % Pad the matrix with 1 copy of this character on all sides
}         % Else (this is a diamond)
t       % Duplicate the matrix
&n      % Determine the number of rows and columns (push separately to stack)
2/Xk    % Compute the radius (half the # of columns rounded up)
w2+     % Flip the stack to get the # of rows and add 2. This is the new radius.
-|      % Subtract the new and old radii and take the absolute value
thYa    % Apply the necessary number of padding zeros to the matrix
|&+     % Take the absolute value and compute the element-wise sum with itself
% and automatically broadcast to a matrix. For a radius of 5 this yields
% the following:
%
%   8   7   6   5   4   5   6   7   8
%   7   6   5   4   3   4   5   6   7
%   6   5   4   3   2   3   4   5   6
%   5   4   3   2   1   2   3   4   5
%   4   3   2   1   0   1   2   3   4
%   5   4   3   2   1   2   3   4   5
%   6   5   4   3   2   3   4   5   6
%   7   6   5   4   3   4   5   6   7
%   8   7   6   5   4   5   6   7   8
%
tleXM   % Duplicate and compute the mode of this matrix (4 in the example above)
=@*     % Find the locations where the matrix is equal to the mode and
% replace with the current character. Set all else to 0.
+       % Add this to the padded version of the previous iteration.
]          % End of if...else
c          % Cast the current matrix as a character array (zeros are spaces)
% Implicit end of for loop and implicit display



JavaScript (ES6), 294288287284256246240238 220 bytes

My first golf on this site. Pass input string to function f, e.g. f('codegolf')

f=s=>{N=n=>(2<<n/2+.5)-3-n%2
D=N(l=s.length)
for(a=[],i=S=D*2+1;i--;)a[i]=a[S+~i]=Array(S).fill
for(;l--;)for(o=n=N(l+1),I=0;I<=n;I++,o-=~l&1)a[y=D+I][x=D+o]=a[x][y]=a[y][D-o]=a[x][D-I]=s[l]
return a.map(r=>r.join)}

-6 bytes thanks to @Sunny Pun: Remove parentheses when passing template strings.

-2 bytes thanks to @ETHproductions: Change S-i-1 to S+~i, l%2||o-- to o-=~l&1.

-18 bytes per suggestions of @Sunny Pun, @edc65: Remove prompt() and console.log() in favor of function format, don't .join() final array of strings

• I count 256 bytes. Any chance you're counting the newlines as two bytes each (\r\n) instead of one (\n)? – user45941 Oct 13 '16 at 1:36
• Making it a function should save bytes by removing prompt and console.log. Also you may use template strings which saves you 2 bytes per function call on Strings (like fill(' ') becomes fill ) – Sunny Pun Oct 13 '16 at 1:44
• Welcome to PPCG! To go along with what the others have said, you can shorten S-i-1 to S+~i, and i%2||o-- to o-=~i&1. – ETHproductions Oct 13 '16 at 7:08
• @Mego Rechecked the count, 256 is correct. Thanks! – darrylyeo Oct 13 '16 at 14:11
• I think a=Array(D*2+1).fill .map((_,$,a)=>[...a]) saves you 10 bytes. – Neil Oct 13 '16 at 18:28 Haskell, 138137 136 bytes q 1=0 q x=(mod x 2+1)*(q(x-1)+1) f x|m<-q$length x,n<-abs<$>[-m..m]=[do j<-n;max" "[c|(k,c)<-zip[1..]x,cycle[max i j,i+j]!!k==q k]|i<-n]  Defines a function f which returns the result as a list of lines -1 byte thanks to @Lynn C++ - 373 366 362 359 bytes -1 by @TuukkaX, -6 by @Kevin Cruijssen, -4 by imports, -3 by @Baum mit Augen #import<string> #import<vector> #define A(x) abs(x-r) using S=std::string;using V=std::vector<S>;int R(int n){return n?(n%2)?R(n-1)+1:2*R(n-1)+2:0;}V f(S w){int l=w.size(),r=R(l-1),s=r*2+1,i,j,k;V x(s);for(i=0;i<s;++i){x[i]=S(s,46);for(j=0;j<s;++j)for(k=0;k<l;++k){if(A(i)<=R(k)&A(j)<=R(k)&k%2?A(i)==R(k)|A(j)==R(k):(A(i)+A(j)==R(k)))x[i][j]=w[k];}}return x;}  http://ideone.com/5y54mx Note: This solution uses the dot ('.') as "space" character to make the empty spaces more visible. To use a space instead, one has to change S(s,46) to S(s,32). The score remains the same. Ungolfed: #import<string> #import<vector> #define A(x) abs(x-r) //r will be the center coordinate using S=std::string; using V=std::vector<S>; int R(int n){ //recursive function returning the radius of a square/diamond return n? //if(n!=0) (n%2)? //if(n%2 != 0) R(n-1)+1 //square -> just increase radius by 1 : 2*R(n-1)+2 //diamond -> radius doubles + 2 : 0 //n==0 -> end of recursion ; } V f(S w){ //function taking a string and returning a vector<string> int l=w.size(),r=R(l-1),s=r*2+1,i,j,k; //r is radius (==center coord), s is size V x(s); //vector<string> for(i=0;i<s;++i){ //loop over vector x[i]=S(s,46); //initialize string with dots. use 32 for spaces for(j=0;j<s;++j) for(k=0;k<l;++k){ //loop over word if( A(i)<=R(k) //check bounds & A(j)<=R(k) & k%2?A(i)==R(k)|A(j)==R(k):(A(i)+A(j)==R(k)) //for square: check if distance to center of one coordinate = R //for diamond: check if sum of distances = R ) x[i][j]=w[k]; //if any is true, replace default char } } return x; }  Try ungolfed online How to use: include<iostream> void printSquare(std::string word){ auto result = f(word); for(auto& s:result) std::cout << s << std::endl; std::cout << std::endl << std::endl; } int main() { printSquare("a"); printSquare("ab"); printSquare("cat"); printSquare("cats"); printSquare("meow"); printSquare("meows"); printSquare("codegolf"); return 0; }  Output: a bbb bab bbb ....t.... ...t.t... ..t...t.. .t.aaa.t. t..aca..t .t.aaa.t. ..t...t.. ...t.t... ....t.... sssssssssss s....t....s s...t.t...s s..t...t..s s.t.aaa.t.s st..aca..ts s.t.aaa.t.s s..t...t..s s...t.t...s s....t....s sssssssssss wwwwwwwwwww w....o....w w...o.o...w w..o...o..w w.o.eee.o.w wo..eme..ow w.o.eee.o.w w..o...o..w w...o.o...w w....o....w wwwwwwwwwww ............s............ ...........s.s........... ..........s...s.......... .........s.....s......... ........s.......s........ .......s.........s....... ......s...........s...... .....s.wwwwwwwwwww.s..... ....s..w....o....w..s.... ...s...w...o.o...w...s... ..s....w..o...o..w....s.. .s.....w.o.eee.o.w.....s. s......wo..eme..ow......s .s.....w.o.eee.o.w.....s. ..s....w..o...o..w....s.. ...s...w...o.o...w...s... ....s..w....o....w..s.... .....s.wwwwwwwwwww.s..... ......s...........s...... .......s.........s....... ........s.......s........ .........s.....s......... ..........s...s.......... ...........s.s........... ............s............ fffffffffffffffffffffffffffffffffffffffffffffffffffffffffff f............................l............................f f...........................l.l...........................f f..........................l...l..........................f f.........................l.....l.........................f f........................l.......l........................f f.......................l.........l.......................f f......................l...........l......................f f.....................l.............l.....................f f....................l...............l....................f f...................l.................l...................f f..................l...................l..................f f.................l.....................l.................f f................l.......................l................f f...............l.........................l...............f f..............l...........................l..............f f.............l.ooooooooooooooooooooooooooo.l.............f f............l..o............g............o..l............f f...........l...o...........g.g...........o...l...........f f..........l....o..........g...g..........o....l..........f f.........l.....o.........g.....g.........o.....l.........f f........l......o........g.......g........o......l........f f.......l.......o.......g.........g.......o.......l.......f f......l........o......g...........g......o........l......f f.....l.........o.....g.eeeeeeeeeee.g.....o.........l.....f f....l..........o....g..e....d....e..g....o..........l....f f...l...........o...g...e...d.d...e...g...o...........l...f f..l............o..g....e..d...d..e....g..o............l..f f.l.............o.g.....e.d.ooo.d.e.....g.o.............l.f fl..............og......ed..oco..de......go..............lf f.l.............o.g.....e.d.ooo.d.e.....g.o.............l.f f..l............o..g....e..d...d..e....g..o............l..f f...l...........o...g...e...d.d...e...g...o...........l...f f....l..........o....g..e....d....e..g....o..........l....f f.....l.........o.....g.eeeeeeeeeee.g.....o.........l.....f f......l........o......g...........g......o........l......f f.......l.......o.......g.........g.......o.......l.......f f........l......o........g.......g........o......l........f f.........l.....o.........g.....g.........o.....l.........f f..........l....o..........g...g..........o....l..........f f...........l...o...........g.g...........o...l...........f f............l..o............g............o..l............f f.............l.ooooooooooooooooooooooooooo.l.............f f..............l...........................l..............f f...............l.........................l...............f f................l.......................l................f f.................l.....................l.................f f..................l...................l..................f f...................l.................l...................f f....................l...............l....................f f.....................l.............l.....................f f......................l...........l......................f f.......................l.........l.......................f f........................l.......l........................f f.........................l.....l.........................f f..........................l...l..........................f f...........................l.l...........................f f............................l............................f fffffffffffffffffffffffffffffffffffffffffffffffffffffffffff +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ +............................................................+............................................................+ +...........................................................+.+...........................................................+ +..........................................................+...+..........................................................+ +.........................................................+.....+.........................................................+ +........................................................+.......+........................................................+ +.......................................................+.........+.......................................................+ +......................................................+...........+......................................................+ +.....................................................+.............+.....................................................+ +....................................................+...............+....................................................+ +...................................................+.................+...................................................+ +..................................................+...................+..................................................+ +.................................................+.....................+.................................................+ +................................................+.......................+................................................+ +...............................................+.........................+...............................................+ +..............................................+...........................+..............................................+ +.............................................+.............................+.............................................+ +............................................+...............................+............................................+ +...........................................+.................................+...........................................+ +..........................................+...................................+..........................................+ +.........................................+.....................................+.........................................+ +........................................+.......................................+........................................+ +.......................................+.........................................+.......................................+ +......................................+...........................................+......................................+ +.....................................+.............................................+.....................................+ +....................................+...............................................+....................................+ +...................................+.................................................+...................................+ +..................................+...................................................+..................................+ +.................................+.....................................................+.................................+ +................................+.......................................................+................................+ +...............................+.........................................................+...............................+ +..............................+...........................................................+..............................+ +.............................+.CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC.+.............................+ +............................+..C............................r............................C..+............................+ +...........................+...C...........................r.r...........................C...+...........................+ +..........................+....C..........................r...r..........................C....+..........................+ +.........................+.....C.........................r.....r.........................C.....+.........................+ +........................+......C........................r.......r........................C......+........................+ +.......................+.......C.......................r.........r.......................C.......+.......................+ +......................+........C......................r...........r......................C........+......................+ +.....................+.........C.....................r.............r.....................C.........+.....................+ +....................+..........C....................r...............r....................C..........+....................+ +...................+...........C...................r.................r...................C...........+...................+ +..................+............C..................r...................r..................C............+..................+ +.................+.............C.................r.....................r.................C.............+.................+ +................+..............C................r.......................r................C..............+................+ +...............+...............C...............r.........................r...............C...............+...............+ +..............+................C..............r...........................r..............C................+..............+ +.............+.................C.............r.ooooooooooooooooooooooooooo.r.............C.................+.............+ +............+..................C............r..o............F............o..r............C..................+............+ +...........+...................C...........r...o...........F.F...........o...r...........C...................+...........+ +..........+....................C..........r....o..........F...F..........o....r..........C....................+..........+ +.........+.....................C.........r.....o.........F.....F.........o.....r.........C.....................+.........+ +........+......................C........r......o........F.......F........o......r........C......................+........+ +.......+.......................C.......r.......o.......F.........F.......o.......r.......C.......................+.......+ +......+........................C......r........o......F...........F......o........r......C........................+......+ +.....+.........................C.....r.........o.....F.eeeeeeeeeee.F.....o.........r.....C.........................+.....+ +....+..........................C....r..........o....F..e....t....e..F....o..........r....C..........................+....+ +...+...........................C...r...........o...F...e...t.t...e...F...o...........r...C...........................+...+ +..+............................C..r............o..F....e..t...t..e....F..o............r..C............................+..+ +.+.............................C.r.............o.F.....e.t.ooo.t.e.....F.o.............r.C.............................+.+ ++..............................Cr..............oF......et..oVo..te......Fo..............rC..............................++ +.+.............................C.r.............o.F.....e.t.ooo.t.e.....F.o.............r.C.............................+.+ +..+............................C..r............o..F....e..t...t..e....F..o............r..C............................+..+ +...+...........................C...r...........o...F...e...t.t...e...F...o...........r...C...........................+...+ +....+..........................C....r..........o....F..e....t....e..F....o..........r....C..........................+....+ +.....+.........................C.....r.........o.....F.eeeeeeeeeee.F.....o.........r.....C.........................+.....+ +......+........................C......r........o......F...........F......o........r......C........................+......+ +.......+.......................C.......r.......o.......F.........F.......o.......r.......C.......................+.......+ +........+......................C........r......o........F.......F........o......r........C......................+........+ +.........+.....................C.........r.....o.........F.....F.........o.....r.........C.....................+.........+ +..........+....................C..........r....o..........F...F..........o....r..........C....................+..........+ +...........+...................C...........r...o...........F.F...........o...r...........C...................+...........+ +............+..................C............r..o............F............o..r............C..................+............+ +.............+.................C.............r.ooooooooooooooooooooooooooo.r.............C.................+.............+ +..............+................C..............r...........................r..............C................+..............+ +...............+...............C...............r.........................r...............C...............+...............+ +................+..............C................r.......................r................C..............+................+ +.................+.............C.................r.....................r.................C.............+.................+ +..................+............C..................r...................r..................C............+..................+ +...................+...........C...................r.................r...................C...........+...................+ +....................+..........C....................r...............r....................C..........+....................+ +.....................+.........C.....................r.............r.....................C.........+.....................+ +......................+........C......................r...........r......................C........+......................+ +.......................+.......C.......................r.........r.......................C.......+.......................+ +........................+......C........................r.......r........................C......+........................+ +.........................+.....C.........................r.....r.........................C.....+.........................+ +..........................+....C..........................r...r..........................C....+..........................+ +...........................+...C...........................r.r...........................C...+...........................+ +............................+..C............................r............................C..+............................+ +.............................+.CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC.+.............................+ +..............................+...........................................................+..............................+ +...............................+.........................................................+...............................+ +................................+.......................................................+................................+ +.................................+.....................................................+.................................+ +..................................+...................................................+..................................+ +...................................+.................................................+...................................+ +....................................+...............................................+....................................+ +.....................................+.............................................+.....................................+ +......................................+...........................................+......................................+ +.......................................+.........................................+.......................................+ +........................................+.......................................+........................................+ +.........................................+.....................................+.........................................+ +..........................................+...................................+..........................................+ +...........................................+.................................+...........................................+ +............................................+...............................+............................................+ +.............................................+.............................+.............................................+ +..............................................+...........................+..............................................+ +...............................................+.........................+...............................................+ +................................................+.......................+................................................+ +.................................................+.....................+.................................................+ +..................................................+...................+..................................................+ +...................................................+.................+...................................................+ +....................................................+...............+....................................................+ +.....................................................+.............+.....................................................+ +......................................................+...........+......................................................+ +.......................................................+.........+.......................................................+ +........................................................+.......+........................................................+ +.........................................................+.....+.........................................................+ +..........................................................+...+..........................................................+ +...........................................................+.+...........................................................+ +............................................................+............................................................+ +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++  • std::vector<S> V has an useless whitespace. – Yytsi Oct 13 '16 at 8:25 • Impressive answer! +1 You can golf it some more though: In if(A(i)<=R(k)&&A(j)<=R(k)&&k%2?A(i)==R(k)||A(j)==R(k) the && and || can be & and | for -3 bytes; and int r=R(w.size()-1),... can become int l=w.size(),r=R(l-1),... and for(k=0;k<w.size();++k) can then become for(k=0;k<l;++k) for another -3 bytes. – Kevin Cruijssen Oct 13 '16 at 9:06 • saved another 4 bytes by using #import and importing string instead of iostream. iostream is only neccessary for printSquare(); – Anedar Oct 13 '16 at 10:32 • As of C++11, you can use using S=std::string; to safe two bytes per typedef. – Baum mit Augen Oct 13 '16 at 10:48 • @grooveplex As stated in the answer: "Note: This solution uses the dot ('.') as "space" character to make the empty spaces more visible. To use a space instead, one has to change S(s,46) to S(s,32). The score remains the same." – Anedar Oct 14 '16 at 8:50 Mathematica, 167 bytes Grid@Fold[g=Normal@SparseArray[h=f;a_List/;Plus@@Abs[a-#-1]==#->#3,2{#,#}+1]+a[#2,#/2+1]&[Length@#+1,#,#2]&;h=f=(h=g;a=ArrayPad)[#,1,#2]&;h@##&,{{#}},{##2}]/.Rule[0,]&  The input must be a list of characters. e.g. Grid@Fold[ ... ]/.Rule[0,]&["i","n","p","u","t"]  JavaScript (ES6), 252 bytes f=([c,...r],a,n,d)=>c?a?d?f(r,[...Array(m=n+n+3)].map((_,i,b)=>b.map((_,j)=>(a[i-g]||[])[j-g]||(i+j-h&&j+h-i&&h+i-j&&i+j-h*3? :c)),h=m>>1,g=m-n>>1),m,0):f(r,[b=[...a].fill(c),...a,b].map(b=>[c,...b,c]),n+2,1):f(r,[[c]],1,0):a.map(b=>b.join).join\n <input oninput=o.textContent=this.value&&f(this.value)><pre id=o> Where \n represents the literal newline character. JavaScript (ES6), 204 229 238 An anonymous function returning an array of strings s=>[...s].map(v=>{T=(x,y)=>((r=[...c[y+z]||' '.repeat(z+z)])[z+x]=r[z-x]=v,c[z+y]=c[z-y]=r.join);for(y=o-~o,o*=++i%2+1;y--;i%2?T(q,y):T(o,q,T(q,o)))q=y-o;++o},l=s.length,z=(2<<-~l/2)-3-l%2,c=[i=o=0])&&c  Less golfed s=>( l = s.length, z = (2 << l/2 + .5) - 3 - l%2, // zero position, total width and height are z+z+1 c = [], // output canvas o = 0, // base drawing offset from z [...s].map( (v, i) => { // execute for each char v at position i in input string // helper function to put current char v at position (z+y, z+x),(z+y,z-x),(z-y,z+x),(z-y,z-x) // as the image has vertical and horizontal symmetry T=(x,y) =>( r = [...c[y+z]||' '.repeat(z+z)]), // convert string to array to set char at given pos r[z+x] = v, r[z-x] = v, c[z+y] = c[z-y] = r.join // array to string again ); // shorter than if(i%2) {for ...}else{for ...} // o is doubled at every other step // and incremented (below) at each step for(y=o+o, i % 2 ? 0 : o=o*2; y >= 0; y--) q = y-o, i % 2 // even and odd steps have different shapes ? ( T(o,q), T(q,o)) : T(q,y); ++o }), c )  Test f= s=>[...s].map(v=>{T=(x,y)=>((r=[...c[y+z]||' '.repeat(z+z)])[z+x]=r[z-x]=v,c[z+y]=c[z-y]=r.join);for(y=o-~o,o*=++i%2+1;y--;i%2?T(q,y):T(o,q,T(q,o)))q=y-o;++o},l=s.length,z=(2<<-~l/2)-3-l%2,c=[i=o=0])&&c function update() { O.textContent=f(I.value).join\n } update() <input id=I value=CodeGolf oninput='update()'> <pre id=O></pre> Java - 429 417 bytes int r,l;int D(int n){return Math.abs(n-r);}int R(int n){return n=(n!=0)?((n%2!=0)?(R(n-1)+1):(2*R(n-1))+2):n;}char[][]C(String a){char[]c=a.toCharArray();l=a.length();r=R(l-1);int s=r*2+1,i,j,k;char[][]x=new char[s][s];for(i=0;i<s;i++){for(j=0;j<s;j++){x[i][j]=' ';for(k=0;k<l;k++){if(D(i)<=R(k)&&D(j)<=R(k)){if(k%2!=0){if(D(i)==R(k)||D(j)==R(k)){x[i][j]=c[k];}}else{if(D(i)+D(j)==R(k)){x[i][j]=c[k];}}}}}}return x;}  Credit goes to @Anedar as it was an influence on the structure of this answer Ungolfed: int r, l; int D(int n) { return Math.abs(n - r); } int R(int n) { return n = (n != 0) ? ((n % 2 != 0) ? (R(n - 1) + 1) : (2 * R(n - 1)) + 2) : n; } char[][] C(String a) { char[] c = a.toCharArray(); l = a.length(); r = R(l - 1); int s = r * 2 + 1, i, j, k; char[][] x = new char[s][s]; for (i = 0; i < s; i++) { for (j = 0; j < s; j++) { x[i][j] = ' '; for (k = 0; k < l; k++) { if (D(i) <= R(k) && D(j) <= R(k)) { if (k % 2 != 0) { if (D(i) == R(k) || D(j) == R(k)) { x[i][j] = c[k]; } } else if (D(i) + D(j) == R(k)) { x[i][j] = c[k]; } } } } } return x; }  JavaScript (ES6), 322 bytes Non Competitive var L=s=>{var A=Array,a,D,c,d=-1,i,k,w,O,Z,P=(u,v)=>{Z=O-(d>>1);a[D?u-v+O:u+Z][D?u+v+O-d+1:v+Z]=c},G=(c,i)=>(D=~i&1)?(d+=2,w=2*d-1):(d+=d+1,w=d);s=[...s];s.map(G);a=A(w).fill(0).map(a=>A(w).fill );O=w>>1;d=-1;s.map((C,i)=>{G(0,i);c=C;for(k=d;k--;)P(0,k),P(d-1,k),P(k,0),P(k,d-1)});return a.map(v=>v.join("")).join("\n")}  Less Golphed var L=s=>{ var A=Array,a,D,c,d=-1,i,k,w,O,Z P=(u,v)=>{ Z=O-(d>>1) a[D?u-v+O:u+Z][D?u+v+O-d+1:v+Z]=c}, G=(c,i)=>(D=~i&1)?(d+=2,w=2*d-1):(d+=d+1,w=d) s=[...s] s.map(G) a=A(w).fill(0).map( a=>A(w).fill ) O=w>>1 d=-1 s.map((C,i)=>{ G(0,i) c=C for(k=d;k--;) P(0,k),P(d-1,k),P(k,0),P(k,d-1)}) return a.map(v=>v.join("")).join("\n") }  Test with L("arty*")  Easy gains by leaving out the leading var L= and .join("\n") in the return statement for -17 bytes, but type them back in to test the code :D It's a two pass answer, evaluating the width (w) required to plot a square or diamond plot, before plotting points with P in the second pass using rotation and translation. d is the dimension (height or width) of an unrotated square before translation or rotation. Rotation and scale by √2 details from Mathematica answer. Use of tagged string template from first answer in this thread. Thanks to both for the learning. Votes for the question and answers. Powershell, 269245 238 bytes $m,$a=$args
if($a){$a|%{$c=$_
$w=$m[0].Length
$m=&({$i=0
($m|%{$_+'.'*$w+'.'})+(0..$w|%{'..'*$w+'.'})|%{($s=$_|% t*y)[--$i]=$c -join$s}},{$m|%{$_+$c}$c*$w+$c})[++$k%2]}$m=($w=$m[0].Length-1)..1+0..$w|%{$m[$_]|%{-join($_[$w..1]+$_)}}}
$m  Ungolfed, explained & test scripted: $f={

# $args is input char array #$m is canvas.
# This script draws a right-bottom quadrant (axes included) on the canvas.
# If $args contains one char only then$m contains this char and whole image at same time.
$m,$a=$args #$a is other chars array
if($a){$a|%{
$c=$_                           # $c is current char$w=$m[0].Length #$w is width of the canvas
$m=&({ #$m is the result of executing one of the two scriptblocks
$i=0 ($m|%{$_+'.'*$w+'.'})+      # expand the canvas
(0..$w|%{'..'*$w+'.'})|%{   # add new lines
($s=$_|% t*y)[--$i]=$c  # take a diamond edge on each line of the canvas
-join$s } },{ # draw Square quadrant$m|%{$_+$c}                 # expand the canvas
$c*$w+$c # add new line })[++$k%2]                      # get a scriptblock from the array and execute it
}

# We have a right-bottom part of drawn AsciiArt now. Flip, flip, paste it.
$w=$m[0].Length-1                   # width of the canvas
$m=$w..1+0..$w|%{$m[$_]|%{ # flip vertical -join($_[$w..1]+$_)             # flip horizontal
}}
}
$m } @( ,('c',@" c "@) ,('ca',@" aaa aca aaa "@) ,('cat',@" ....t.... ...t.t... ..t...t.. .t.aaa.t. t..aca..t .t.aaa.t. ..t...t.. ...t.t... ....t.... "@) ,('cats',@" sssssssssss s....t....s s...t.t...s s..t...t..s s.t.aaa.t.s st..aca..ts s.t.aaa.t.s s..t...t..s s...t.t...s s....t....s sssssssssss "@) ,('meows',@" ............s............ ...........s.s........... ..........s...s.......... .........s.....s......... ........s.......s........ .......s.........s....... ......s...........s...... .....s.wwwwwwwwwww.s..... ....s..w....o....w..s.... ...s...w...o.o...w...s... ..s....w..o...o..w....s.. .s.....w.o.eee.o.w.....s. s......wo..eme..ow......s .s.....w.o.eee.o.w.....s. ..s....w..o...o..w....s.. ...s...w...o.o...w...s... ....s..w....o....w..s.... .....s.wwwwwwwwwww.s..... ......s...........s...... .......s.........s....... ........s.......s........ .........s.....s......... ..........s...s.......... ...........s.s........... ............s............ "@) ,('codegolf',@" fffffffffffffffffffffffffffffffffffffffffffffffffffffffffff f............................l............................f f...........................l.l...........................f f..........................l...l..........................f f.........................l.....l.........................f f........................l.......l........................f f.......................l.........l.......................f f......................l...........l......................f f.....................l.............l.....................f f....................l...............l....................f f...................l.................l...................f f..................l...................l..................f f.................l.....................l.................f f................l.......................l................f f...............l.........................l...............f f..............l...........................l..............f f.............l.ooooooooooooooooooooooooooo.l.............f f............l..o............g............o..l............f f...........l...o...........g.g...........o...l...........f f..........l....o..........g...g..........o....l..........f f.........l.....o.........g.....g.........o.....l.........f f........l......o........g.......g........o......l........f f.......l.......o.......g.........g.......o.......l.......f f......l........o......g...........g......o........l......f f.....l.........o.....g.eeeeeeeeeee.g.....o.........l.....f f....l..........o....g..e....d....e..g....o..........l....f f...l...........o...g...e...d.d...e...g...o...........l...f f..l............o..g....e..d...d..e....g..o............l..f f.l.............o.g.....e.d.ooo.d.e.....g.o.............l.f fl..............og......ed..oco..de......go..............lf f.l.............o.g.....e.d.ooo.d.e.....g.o.............l.f f..l............o..g....e..d...d..e....g..o............l..f f...l...........o...g...e...d.d...e...g...o...........l...f f....l..........o....g..e....d....e..g....o..........l....f f.....l.........o.....g.eeeeeeeeeee.g.....o.........l.....f f......l........o......g...........g......o........l......f f.......l.......o.......g.........g.......o.......l.......f f........l......o........g.......g........o......l........f f.........l.....o.........g.....g.........o.....l.........f f..........l....o..........g...g..........o....l..........f f...........l...o...........g.g...........o...l...........f f............l..o............g............o..l............f f.............l.ooooooooooooooooooooooooooo.l.............f f..............l...........................l..............f f...............l.........................l...............f f................l.......................l................f f.................l.....................l.................f f..................l...................l..................f f...................l.................l...................f f....................l...............l....................f f.....................l.............l.....................f f......................l...........l......................f f.......................l.........l.......................f f........................l.......l........................f f.........................l.....l.........................f f..........................l...l..........................f f...........................l.l...........................f f............................l............................f fffffffffffffffffffffffffffffffffffffffffffffffffffffffffff "@) #,('codegolfes',"") ) | % {$s, $e =$_
$c =$s-split''-ne''
$r = &$f @c
$r =$r-join"n"
"$($e-eq$r):$sn\$r"
}