printrun-src/printrun/gl/trackball.py

# This file is part of the Printrun suite.
#
# Printrun is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Printrun is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Printrun.  If not, see <http://www.gnu.org/licenses/>.

import math

from pyglet.gl import GLdouble

def cross(v1, v2):
    return [v1[1] * v2[2] - v1[2] * v2[1],
            v1[2] * v2[0] - v1[0] * v2[2],
            v1[0] * v2[1] - v1[1] * v2[0]]

def trackball(p1x, p1y, p2x, p2y, r):
    TRACKBALLSIZE = r

    if p1x == p2x and p1y == p2y:
        return [0.0, 0.0, 0.0, 1.0]

    p1 = [p1x, p1y, project_to_sphere(TRACKBALLSIZE, p1x, p1y)]
    p2 = [p2x, p2y, project_to_sphere(TRACKBALLSIZE, p2x, p2y)]
    a = cross(p2, p1)

    d = map(lambda x, y: x - y, p1, p2)
    t = math.sqrt(sum(x * x for x in d)) / (2.0 * TRACKBALLSIZE)

    if t > 1.0:
        t = 1.0
    if t < -1.0:
        t = -1.0
    phi = 2.0 * math.asin(t)

    return axis_to_quat(a, phi)

def axis_to_quat(a, phi):
    lena = math.sqrt(sum(x * x for x in a))
    q = [x * (1 / lena) for x in a]
    q = [x * math.sin(phi / 2.0) for x in q]
    q.append(math.cos(phi / 2.0))
    return q

def build_rotmatrix(q):
    m = (GLdouble * 16)()
    m[0] = 1.0 - 2.0 * (q[1] * q[1] + q[2] * q[2])
    m[1] = 2.0 * (q[0] * q[1] - q[2] * q[3])
    m[2] = 2.0 * (q[2] * q[0] + q[1] * q[3])
    m[3] = 0.0

    m[4] = 2.0 * (q[0] * q[1] + q[2] * q[3])
    m[5] = 1.0 - 2.0 * (q[2] * q[2] + q[0] * q[0])
    m[6] = 2.0 * (q[1] * q[2] - q[0] * q[3])
    m[7] = 0.0

    m[8] = 2.0 * (q[2] * q[0] - q[1] * q[3])
    m[9] = 2.0 * (q[1] * q[2] + q[0] * q[3])
    m[10] = 1.0 - 2.0 * (q[1] * q[1] + q[0] * q[0])
    m[11] = 0.0

    m[12] = 0.0
    m[13] = 0.0
    m[14] = 0.0
    m[15] = 1.0
    return m


def project_to_sphere(r, x, y):
    d = math.sqrt(x * x + y * y)
    if (d < r * 0.70710678118654752440):
        return math.sqrt(r * r - d * d)
    else:
        t = r / 1.41421356237309504880
        return t * t / d


def mulquat(q1, rq):
    return [q1[3] * rq[0] + q1[0] * rq[3] + q1[1] * rq[2] - q1[2] * rq[1],
            q1[3] * rq[1] + q1[1] * rq[3] + q1[2] * rq[0] - q1[0] * rq[2],
            q1[3] * rq[2] + q1[2] * rq[3] + q1[0] * rq[1] - q1[1] * rq[0],
            q1[3] * rq[3] - q1[0] * rq[0] - q1[1] * rq[1] - q1[2] * rq[2]]