/***************************************************************************
*
* Multitouch X driver
* Copyright (C) 2011 Ryan Bourgeois
*
* This program 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 2 of the License, or
* (at your option) any later version.
*
* This program 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 this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
**************************************************************************/
/* Some bastardized trig functions. These calculations flip the
* Y axis since that axis on touchpads is opposite that of the
* Cartesian system.
*/
#ifndef MT_TRIG_H
#define MT_TRIG_H
#define TR_NONE -1
#define TR_DIR_UP 0
#define TR_DIR_RT 2
#define TR_DIR_DN 4
#define TR_DIR_LT 6
/* Determine the direction of a vector. This uses the slope of the
* vector to approximate the angle, as such it is only accurate at
* increments of 45 degrees. This is sufficient for our uses.
*
* The returned value is 0 <= a < 8 such that the circle is split
* into 45 degree sections. Each whole number lies 45 degrees apart
* and so whole numbers are exact. All fractional parts are
* aproximations.
*
* TR_NONE will be returned if the magnitude of the vector is zero.
*/
double trig_direction(double dx, double dy);
/* Generalize a direction. Returns TR_NONE, TR_DIR_UP, TR_DIR_RT,
* TR_DIR_DN, or TR_DIR_LT.
*/
int trig_generalize(double dir);
/* Add two angles.
*/
double trig_angles_add(double a1, double a2);
/* Subtract two angles.
*/
double trig_angles_sub(double a1, double a2);
/* Calculate the acute angle between two angles.
*/
double trig_angles_acute(double a1, double a2);
/* Average a collection of angles.
*/
double trig_angles_avg(double* angles, int len);
/* Compare two angles. Returns 0 if a1 == a2. Returns < 0 if a1 < a2.
* Returns > 0 if a1 > a2.
*/
int trig_angles_cmp(double a1, double a2);
#endif