src/transform.lisp @ 0d86e460026d

(in-package :flax.transform)

(defun id ()
  (meye 3))

(defun scale (m x y)
  (m* (mat x 0 0
           0 y 0
           0 0 1)
      m))

(defun rotate (m angle)
  (m* (mat (cos angle)     (sin angle) 0
           (- (sin angle)) (cos angle) 0
           0               0           1)
      m))

(defun translate (m x y)
  (m* (mat 1 0 x
           0 1 y
           0 0 1)
      m))


(defmacro transformation (&rest transforms)
  `(-<> (id)
     ,@(iterate (for (name . body) :in transforms)
                (collect `(,name <> ,@body)))))


(defgeneric ntransform (object transformation))

(defmethod ntransform ((vector vec3) transformation)
  (nm* transformation vector)
  vector)

(defmethod ntransform ((magnitude float) transformation)
  (with-fast-matref (m transformation 3)
    (let* ((a (m 0 0))
           (b (m 0 1))
           (c (m 1 0))
           (d (m 1 1))
           (scale (sqrt (/ (+ (square (+ a b))
                              (square (+ c d)))
                           2.0))))
      (* magnitude scale))))

(defmethod ntransform ((sequence sequence) transformation)
  (map-into sequence (rcurry #'ntransform transformation) sequence))