"""Convenience class for holding a single symbolic homogeneous transform and
operating on it in-place.  This is similar to the use of the current
transformation matrix in OpenGL..

transform3d.py, Copyright (c) 2014-2017 Garth Zeglin. All rights
reserved. Licensed under the terms of the BSD 3-clause license as included in
LICENSE.

"""

import sympy as sym
from threexform import *

#================================================================
class Transform3D:
    """Convenience class for holding a single symbolic homogeneous transform
    representing a coordinate frame and operating on it in-place.  This is
    similar to the use of the current transformation matrix in OpenGL.

    Each operation modifies the transformation state and returns the object
    itself to allow sequential composition, e.g.

    Transform3D().translate(x,y,z).rotate_x( angle).rotate_y(angle)

    Attributes:
    ctm -- the 4x4 homogenous transform

    Methods:
    translate( x,y,z )
    rotate_x( angle )
    rotate_y( angle )
    rotate_z( angle )
    set_identity()

    """

    def __init__(self):
        self.ctm = sym.eye(4)
        return

    def set_identity(self):
        self.ctm = sym.eye(4)
        return self

    def translate(self, x, y, z):
        self.ctm = self.ctm * translation(x, y, z)
        return self

    def rotate_x(self, angle):
        self.ctm = self.ctm * rotation_x(angle)
        return self

    def rotate_y(self, angle):
        self.ctm = self.ctm * rotation_y(angle)
        return self

    def rotate_z( self, angle ):
        self.ctm = self.ctm * rotation_z(angle)
        return self

#================================================================