diff options
author | Antony Riakiotakis <kalast@gmail.com> | 2014-08-27 19:29:15 +0400 |
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committer | Antony Riakiotakis <kalast@gmail.com> | 2014-08-27 19:29:15 +0400 |
commit | 7d5c16c085a6059262b5d25cd1833609b643c649 (patch) | |
tree | c512ae93b6b12708484feee3fcaf8141837c82aa /source/blender/blenlib/intern/BLI_dial.c | |
parent | 70a49423d9a44a86bd5c77ce8027097c56702b65 (diff) |
Add a reusable dial mechanism to get rotations around a center and an
initial position. The system supports arbitrarily big angles.
Diffstat (limited to 'source/blender/blenlib/intern/BLI_dial.c')
-rw-r--r-- | source/blender/blenlib/intern/BLI_dial.c | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/source/blender/blenlib/intern/BLI_dial.c b/source/blender/blenlib/intern/BLI_dial.c new file mode 100644 index 00000000000..943e0b2bf99 --- /dev/null +++ b/source/blender/blenlib/intern/BLI_dial.c @@ -0,0 +1,99 @@ +/* + * ***** BEGIN GPL LICENSE BLOCK ***** + * + * 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 Street, Fifth Floor, Boston, MA 02110-1301, USA. + * + * ***** END GPL LICENSE BLOCK ***** + */ + +#include "BLI_dial.h" +#include "BLI_math.h" + +#include "MEM_guardedalloc.h" + +struct Dial { + /* center of the dial */ + float center[2]; + + /* threshold of the dial. Distance of current position has to be greater + * than the threshold to be used in any calculations */ + float threshold_squared; + + /* the direction of the first dial position exceeding the threshold. This + * is later used as the basis against which rotation angle is calculated */ + float initial_direction[2]; + + /* cache the last angle to detect rotations bigger than -/+ PI */ + float last_angle; + + /* number of full rotations */ + int rotations; + + /* has initial_direction been initialized */ + bool initialized; +}; + + +Dial * BLI_dial_initialize(float start_position[2], float threshold) +{ + Dial *dial = MEM_callocN(sizeof(Dial), "dial"); + + copy_v2_v2(dial->center, start_position); + dial->threshold_squared = threshold * threshold; + + return dial; +} + +float BLI_dial_angle(Dial *dial, float current_position[2]) +{ + float current_direction[2]; + + sub_v2_v2v2(current_direction, current_position, dial->center); + + /* only update when we have enough precision, by having the mouse adequately away from center */ + if (len_squared_v2(current_direction) > dial->threshold_squared) { + float angle; + float cosval, sinval; + + normalize_v2(current_direction); + + if (!dial->initialized) { + copy_v2_v2(dial->initial_direction, current_direction); + dial->initialized = true; + } + + /* calculate mouse angle between initial and final mouse position */ + cosval = dot_v2v2(current_direction, dial->initial_direction); + sinval = cross_v2v2(current_direction, dial->initial_direction); + + /* clamp to avoid nans in acos */ + angle = atan2(sinval, cosval); + + /* change of sign, we passed the 180 degree threshold. This means we need to add a turn. + * to distinguish between transition from 0 to -1 and -PI to +PI, use comparison with PI/2 */ + if ((angle * dial->last_angle < 0.0f) && (fabsf(dial->last_angle) > (float)M_PI_2)) + { + if (dial->last_angle < 0) + dial->rotations--; + else + dial->rotations++; + } + dial->last_angle = angle; + + return angle + 2.0f * (float)M_PI * dial->rotations; + } + + return dial->last_angle; +} |