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;;;; turtle-system.lisp
(in-package #:l-system)
;;;(matrix* translate rotate scale)
(export 'f)
(export '[)
(export '])
(defun turtle-system (fn list radians)
(iter (with pos = (sb-cga:vec 0.0 0.0 0.0))
(with vec = (sb-cga:vec 0.0 1.0 0.0))
(with pile = '())
(with angle = radians)
(for item in list)
(case item
;;Move forward one unit,adding data to mesh.
((f)
(let ((new-pos
(vec+ pos vec)))
(appending (funcall fn pos new-pos vec))
(setf pos new-pos)))
;;Move forward one unit,without adding data to mesh.
((j)
(setf pos
(vec+ pos
vec)))
;;Rotate left on axis z
((+)
(setf vec
(vec-rotate-around vec (vec 0.0 0.0 1.0) angle)))
;;Rotate right on axis z
((-)
(setf vec
(vec-rotate-around vec (vec 0.0 0.0 -1.0) angle)))
;;Rotate left on axis y
((&)
(setf vec
(vec-rotate-around vec (vec 0.0 1.0 0.0) angle)))
;;Rotate right on axis y
((^)
(setf vec
(vec-rotate-around vec (vec 0.0 -1.0 0.0) angle)))
;;Rotate left on axis x
((\ )
(setf vec
(vec-rotate-around vec (vec 1.0 0.0 0.0) angle)))
;;Rotate right on axis x
((/)
(setf vec
(vec-rotate-around vec (vec -1.0 0.0 0.0) angle)))
;;Push the current turtle state onto a stack
(([)
(push (list pos vec)
pile))
;;Pop the turtle stack, restoring an earlier state
((])
(let* ((asd (pop pile))
(pos0 (first asd))
(vec0 (second asd)))
(setf pos pos0)
(setf vec vec0))))))
;;; Turgle utils
(defun list-of-vectors->list (list-of-vectors)
(iterconcat #'(lambda (vec)
(concatenate 'list
vec))
list-of-vectors))
(defun vec-rotate-around (vec vec-rotation angle)
"Rotate vec around vec-rotation axis by angle"
(transform-point (vec 0.0 0.0 0.0)
(matrix*
(rotate-around vec-rotation angle)
(translate vec))))
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