Someone

FLOAT X
FLOAT Y
: LineDDA // x1 y1 x2 y2 color
 2 PICK 5 PICK - // x2-x1
 2 PICK 5 PICK - // y2-y1
 2DUPS MAX       // L = max(x2-x1,y2-y1)
 DUP S>F ROT ROT           // FS: L
 FDUP S>F FSWAP F/         // FS: L dY/L
 FSWAP S>F FSWAP F/ FSWAP  // FS: dX/L dY/L

 // DS: x1 y1 x2 y2 color L
  2 XCHG DROP
  3 PICK 3 XCHG DROP
  4 PICK 4 XCHG DROP
  4 XCHG DROP
  ROT ROT
 // DS: color L x1 y1
 
 S>F Y F!
 S>F X F!
 // FS: dx/L dy/L
 // DS: color L
 1+ 0 DO
  FOVER X F@ F+ FDUP X F! F>S
  FDUP  Y F@ F+ FDUP Y F! F>S
  2 PICK PIXEL
 LOOP
 DROP
 FDROP FDROP
;
10 50 200 500 65000 LineDDA