;;;; affine.lisp

(in-package #:wheelwork)

(defclass/std affine (unit)
  ((cached-model cached-projected-matrix cached-application :a)
   (base-width base-height :r :std 1.0 :doc "Determined by content.")
   (scale-x scale-y :std 1.0)
   (rotation x y :std 0.0)))

(defmethod (setf closer-mop:slot-value-using-class) :after
    (newval class (affine affine) slot)
  (case (closer-mop:slot-definition-name slot)
    ((x y scale-x scale-y rotation)
     (setf (cached-model affine) nil
           (cached-projected-matrix affine) nil))))

(defun scale-by (affine amount)
  (with-slots (scale-x scale-y) affine
    (setf scale-x (* amount scale-x)
          scale-y (* amount scale-y))))

(defun set-width-preserve-aspect (affine new-width)
  (scale-by affine (/ new-width (width affine))))

(defun set-height-preserve-aspect (affine new-height)
  (scale-by affine (/ new-height (height affine) )))

(defun width (affine)
  (with-slots (scale-x base-width) affine
    (* scale-x base-width)))

(defun height (affine)
  (with-slots (scale-y base-height) affine
    (* scale-y base-height)))

(defun (setf width) (newval affine)
  (with-slots (scale-x base-width) affine
    (setf scale-x (coerce (/ newval base-width) 'single-float))))

(defun (setf height) (newval affine)
  (with-slots (scale-y base-height) affine
    (setf scale-y (coerce (/ newval base-height) 'single-float))))

(defmethod model-matrix :around ((u affine))
  (or (cached-model u)
      (setf (cached-model u)
            (call-next-method))))

(defmethod model-matrix ((u affine))
  (let ((m (mat:meye 4)))
    (with-slots (x y base-width scale-x base-height scale-y rotation) u 
      (let ((uw (* base-width scale-x))
            (uh (* base-height scale-y)))
        (mat:nmtranslate m (vec:vec x y 0.0))

        (mat:nmtranslate m (vec:v* 0.5 (vec:vec uw uh 0.0)))
        (mat:nmrotate  m vec:+vz+ rotation)
        (mat:nmtranslate m (vec:v* -0.5 (vec:vec uw uh 0.0)))
        
        (mat:nmscale m (vec:vec uw uh 1.0))))
    m))


(defun projected-matrix (affine)
  (or (cached-projected-matrix affine)
      (setf (cached-projected-matrix affine)
            (mat:marr (mat:m* (application-projection (app-of-unit affine))
                              (model-matrix affine))))))