I always say “A picture is worth a thousand words” and so I sometimes use ascii art in comments. For example when writing code for a 2D-game, I have written a funtion, which returns an id for the next edge of a rectangle, and also a function which returns the sector, when the rectangle is divided into 4 triangles. The C-code looks like this:

/*   o-------> x   |   |  (left, top)  _____   |              |     |   v              |     |                  |_____|   y                      (right, bottom)  */ struct rect {     double left, top, right bottom; };  enum face { TOP, RIGHT, BOTTOM, LEFT };  /*     ___________    |',       ,'|    |  ',___,'  |    |  ,'   ',  |    |,'_______',|  */ enum face getNextEdge(double x, double y, struct rect* r) {      enum face f = TOP;     double dist = y - r->top;      double dist2 = r->right - x;     if(dist2 < dist) { dist = dist2; f = RIGHT; };      dist2 = r->bottom - y;     if(dist2 < dist) { dist = dist2; f = DOWN; };      dist2 = x - r->left;     if(dist2 < dist) { dist = dist2; f = LEFT; };       return f; },   /*     ___________    |'-_     _-'|    |   '-_-'   |    |  _-' '-_  |    |-'_______'-|  */ enum face getSector(double x, double y, struct rect* r) {      // ...  }; 

What do you think of ascii art in comments? And where did you use ascii art?