Commit: 7d5c16c085a6059262b5d25cd1833609b643c649
Author: Antony Riakiotakis
Date: Wed Aug 27 17:29:15 2014 +0200
Branches: master
https://developer.blender.org/rB7d5c16c085a6059262b5d25cd1833609b643c649
Add a reusable dial mechanism to get rotations around a center and an
initial position. The system supports arbitrarily big angles.
===================================================================
A source/blender/blenlib/BLI_dial.h
M source/blender/blenlib/CMakeLists.txt
A source/blender/blenlib/intern/BLI_dial.c
===================================================================
diff --git a/source/blender/blenlib/BLI_dial.h
b/source/blender/blenlib/BLI_dial.h
new file mode 100644
index 0000000..61420f4
--- /dev/null
+++ b/source/blender/blenlib/BLI_dial.h
@@ -0,0 +1,59 @@
+/*
+ * ***** 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 *****
+ */
+
+#ifndef __BLI_DIAL_H__
+#define __BLI_DIAL_H__
+
+/** \file BLI_dial.h
+ * \ingroup bli
+ *
+ * \note dials act similar to old rotation based phones and output an angle.
+ *
+ * They just are initialized with the center of the dial and a threshold value
as input.
+ *
+ * When the distance of the current position of the dial from the center
+ * exceeds the threshold, this position is used to calculate the initial
direction.
+ * After that, the angle from the initial direction is calculated based on
+ * current and previous directions of the digit, and returned to the user.
+ *
+ * Usage examples:
+ * \code
+ * float start_position[2] = {0.0f, 0.0f};
+ * float current_position[2];
+ * float threshold = 0.5f;
+ * float angle;
+ * Dial *dial;
+ *
+ * dial = BLI_dial_initialize(start_position, threshold);
+ *
+ * angle = BLI_dial_angle(dial, curent_position);
+ *
+ * MEM_freeN(dial);
+ *
+ * \endcode
+ */
+
+typedef struct Dial Dial;
+
+Dial * BLI_dial_initialize(float start_position[2], float threshold);
+
+float BLI_dial_angle(Dial *dial, float current_position[2]);
+
+#endif /* __BLI_DIAL_H__ */
\ No newline at end of file
diff --git a/source/blender/blenlib/CMakeLists.txt
b/source/blender/blenlib/CMakeLists.txt
index 0c1c5f1..dd02bcf 100644
--- a/source/blender/blenlib/CMakeLists.txt
+++ b/source/blender/blenlib/CMakeLists.txt
@@ -42,6 +42,7 @@ set(INC_SYS
set(SRC
intern/BLI_args.c
intern/BLI_array.c
+ intern/BLI_dial.c
intern/BLI_dynstr.c
intern/BLI_ghash.c
intern/BLI_heap.c
@@ -118,6 +119,7 @@ set(SRC
BLI_compiler_attrs.h
BLI_compiler_compat.h
BLI_convexhull2d.h
+ BLI_dial.h
BLI_dlrbTree.h
BLI_dynlib.h
BLI_dynstr.h
diff --git a/source/blender/blenlib/intern/BLI_dial.c
b/source/blender/blenlib/intern/BLI_dial.c
new file mode 100644
index 0000000..943e0b2
--- /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;
+}
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