/******************************************************************************
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* Spine Runtimes License Agreement
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* Last updated July 28, 2023. Replaces all prior versions.
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*
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* Copyright (c) 2013-2023, Esoteric Software LLC
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*
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* Integration of the Spine Runtimes into software or otherwise creating
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* derivative works of the Spine Runtimes is permitted under the terms and
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* conditions of Section 2 of the Spine Editor License Agreement:
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* http://esotericsoftware.com/spine-editor-license
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*
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* Otherwise, it is permitted to integrate the Spine Runtimes into software or
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* otherwise create derivative works of the Spine Runtimes (collectively,
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* "Products"), provided that each user of the Products must obtain their own
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* Spine Editor license and redistribution of the Products in any form must
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* include this license and copyright notice.
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*
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* THE SPINE RUNTIMES ARE PROVIDED BY ESOTERIC SOFTWARE LLC "AS IS" AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL ESOTERIC SOFTWARE LLC BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES,
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* BUSINESS INTERRUPTION, OR LOSS OF USE, DATA, OR PROFITS) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THE
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* SPINE RUNTIMES, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*****************************************************************************/
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using System;
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namespace Spine {
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using Physics = Skeleton.Physics;
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/// <summary>
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/// <para>
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/// Stores the current pose for an IK constraint. An IK constraint adjusts the rotation of 1 or 2 constrained bones so the tip of
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/// the last bone is as close to the target bone as possible.</para>
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/// <para>
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/// See <a href="http://esotericsoftware.com/spine-ik-constraints">IK constraints</a> in the Spine User Guide.</para>
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/// </summary>
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public class IkConstraint : IUpdatable {
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internal readonly IkConstraintData data;
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internal readonly ExposedList<Bone> bones = new ExposedList<Bone>();
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internal Bone target;
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internal int bendDirection;
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internal bool compress, stretch;
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internal float mix = 1, softness;
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internal bool active;
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public IkConstraint (IkConstraintData data, Skeleton skeleton) {
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if (data == null) throw new ArgumentNullException("data", "data cannot be null.");
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this.data = data;
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bones = new ExposedList<Bone>(data.bones.Count);
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foreach (BoneData boneData in data.bones)
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bones.Add(skeleton.bones.Items[boneData.index]);
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target = skeleton.bones.Items[data.target.index];
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mix = data.mix;
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softness = data.softness;
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bendDirection = data.bendDirection;
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compress = data.compress;
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stretch = data.stretch;
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}
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/// <summary>Copy constructor.</summary>
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public IkConstraint (IkConstraint constraint, Skeleton skeleton)
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: this(constraint.data, skeleton) {
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mix = constraint.mix;
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softness = constraint.softness;
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bendDirection = constraint.bendDirection;
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compress = constraint.compress;
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stretch = constraint.stretch;
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}
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public void SetToSetupPose () {
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IkConstraintData data = this.data;
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mix = data.mix;
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softness = data.softness;
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bendDirection = data.bendDirection;
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compress = data.compress;
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stretch = data.stretch;
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}
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public void Update (Physics physics) {
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if (mix == 0) return;
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Bone target = this.target;
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Bone[] bones = this.bones.Items;
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switch (this.bones.Count) {
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case 1:
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Apply(bones[0], target.worldX, target.worldY, compress, stretch, data.uniform, mix);
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break;
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case 2:
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Apply(bones[0], bones[1], target.worldX, target.worldY, bendDirection, stretch, data.uniform, softness, mix);
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break;
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}
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}
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/// <summary>The bones that will be modified by this IK constraint.</summary>
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public ExposedList<Bone> Bones {
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get { return bones; }
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}
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/// <summary>The bone that is the IK target.</summary>
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public Bone Target {
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get { return target; }
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set { target = value; }
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}
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/// <summary>A percentage (0-1) that controls the mix between the constrained and unconstrained rotation.
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/// <para>
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/// For two bone IK: if the parent bone has local nonuniform scale, the child bone's local Y translation is set to 0.
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/// </para></summary>
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public float Mix {
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get { return mix; }
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set { mix = value; }
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}
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/// <summary>For two bone IK, the target bone's distance from the maximum reach of the bones where rotation begins to slow. The bones
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/// will not straighten completely until the target is this far out of range.</summary>
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public float Softness {
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get { return softness; }
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set { softness = value; }
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}
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/// <summary>For two bone IK, controls the bend direction of the IK bones, either 1 or -1.</summary>
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public int BendDirection {
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get { return bendDirection; }
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set { bendDirection = value; }
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}
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/// <summary>For one bone IK, when true and the target is too close, the bone is scaled to reach it.</summary>
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public bool Compress {
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get { return compress; }
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set { compress = value; }
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}
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/// <summary>When true and the target is out of range, the parent bone is scaled to reach it.
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/// <para>
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/// For two bone IK: 1) the child bone's local Y translation is set to 0,
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/// 2) stretch is not applied if <see cref="Softness"/> is > 0,
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/// and 3) if the parent bone has local nonuniform scale, stretch is not applied.
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/// </para></summary>
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public bool Stretch {
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get { return stretch; }
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set { stretch = value; }
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}
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public bool Active {
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get { return active; }
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}
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/// <summary>The IK constraint's setup pose data.</summary>
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public IkConstraintData Data {
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get { return data; }
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}
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override public string ToString () {
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return data.name;
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}
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/// <summary>Applies 1 bone IK. The target is specified in the world coordinate system.</summary>
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static public void Apply (Bone bone, float targetX, float targetY, bool compress, bool stretch, bool uniform,
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float alpha) {
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if (bone == null) throw new ArgumentNullException("bone", "bone cannot be null.");
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Bone p = bone.parent;
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float pa = p.a, pb = p.b, pc = p.c, pd = p.d;
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float rotationIK = -bone.ashearX - bone.arotation;
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float tx = 0, ty = 0;
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switch (bone.inherit) {
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case Inherit.OnlyTranslation:
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tx = (targetX - bone.worldX) * Math.Sign(bone.skeleton.ScaleX);
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ty = (targetY - bone.worldY) * Math.Sign(bone.skeleton.ScaleY);
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break;
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case Inherit.NoRotationOrReflection: {
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float s = Math.Abs(pa * pd - pb * pc) / Math.Max(0.0001f, pa * pa + pc * pc);
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float sa = pa / bone.skeleton.scaleX;
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float sc = pc / bone.skeleton.ScaleY;
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pb = -sc * s * bone.skeleton.scaleX;
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pd = sa * s * bone.skeleton.ScaleY;
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rotationIK += MathUtils.Atan2Deg(sc, sa);
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goto default; // Fall through.
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}
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default: {
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float x = targetX - p.worldX, y = targetY - p.worldY;
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float d = pa * pd - pb * pc;
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if (Math.Abs(d) <= 0.0001f) {
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tx = 0;
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ty = 0;
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} else {
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tx = (x * pd - y * pb) / d - bone.ax;
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ty = (y * pa - x * pc) / d - bone.ay;
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}
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break;
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}
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}
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rotationIK += MathUtils.Atan2Deg(ty, tx);
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if (bone.ascaleX < 0) rotationIK += 180;
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if (rotationIK > 180)
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rotationIK -= 360;
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else if (rotationIK < -180) //
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rotationIK += 360;
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float sx = bone.ascaleX, sy = bone.ascaleY;
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if (compress || stretch) {
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switch (bone.inherit) {
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case Inherit.NoScale:
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case Inherit.NoScaleOrReflection:
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tx = targetX - bone.worldX;
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ty = targetY - bone.worldY;
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break;
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}
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float b = bone.data.length * sx;
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if (b > 0.0001f) {
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float dd = tx * tx + ty * ty;
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if ((compress && dd < b * b) || (stretch && dd > b * b)) {
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float s = ((float)Math.Sqrt(dd) / b - 1) * alpha + 1;
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sx *= s;
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if (uniform) sy *= s;
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}
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}
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}
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bone.UpdateWorldTransform(bone.ax, bone.ay, bone.arotation + rotationIK * alpha, sx, sy, bone.ashearX, bone.ashearY);
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}
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/// <summary>Applies 2 bone IK. The target is specified in the world coordinate system.</summary>
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/// <param name="child">A direct descendant of the parent bone.</param>
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static public void Apply (Bone parent, Bone child, float targetX, float targetY, int bendDir, bool stretch, bool uniform,
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float softness, float alpha) {
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if (parent == null) throw new ArgumentNullException("parent", "parent cannot be null.");
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if (child == null) throw new ArgumentNullException("child", "child cannot be null.");
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if (parent.inherit != Inherit.Normal || child.inherit != Inherit.Normal) return;
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float px = parent.ax, py = parent.ay, psx = parent.ascaleX, psy = parent.ascaleY, sx = psx, sy = psy, csx = child.ascaleX;
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int os1, os2, s2;
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if (psx < 0) {
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psx = -psx;
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os1 = 180;
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s2 = -1;
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} else {
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os1 = 0;
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s2 = 1;
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}
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if (psy < 0) {
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psy = -psy;
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s2 = -s2;
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}
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if (csx < 0) {
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csx = -csx;
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os2 = 180;
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} else
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os2 = 0;
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float cx = child.ax, cy, cwx, cwy, a = parent.a, b = parent.b, c = parent.c, d = parent.d;
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bool u = Math.Abs(psx - psy) <= 0.0001f;
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if (!u || stretch) {
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cy = 0;
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cwx = a * cx + parent.worldX;
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cwy = c * cx + parent.worldY;
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} else {
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cy = child.ay;
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cwx = a * cx + b * cy + parent.worldX;
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cwy = c * cx + d * cy + parent.worldY;
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}
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Bone pp = parent.parent;
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a = pp.a;
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b = pp.b;
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c = pp.c;
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d = pp.d;
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float id = a * d - b * c, x = cwx - pp.worldX, y = cwy - pp.worldY;
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id = Math.Abs(id) <= 0.0001f ? 0 : 1 / id;
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float dx = (x * d - y * b) * id - px, dy = (y * a - x * c) * id - py;
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float l1 = (float)Math.Sqrt(dx * dx + dy * dy), l2 = child.data.length * csx, a1, a2;
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if (l1 < 0.0001f) {
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Apply(parent, targetX, targetY, false, stretch, false, alpha);
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child.UpdateWorldTransform(cx, cy, 0, child.ascaleX, child.ascaleY, child.ashearX, child.ashearY);
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return;
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}
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x = targetX - pp.worldX;
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y = targetY - pp.worldY;
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float tx = (x * d - y * b) * id - px, ty = (y * a - x * c) * id - py;
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float dd = tx * tx + ty * ty;
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if (softness != 0) {
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softness *= psx * (csx + 1) * 0.5f;
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float td = (float)Math.Sqrt(dd), sd = td - l1 - l2 * psx + softness;
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if (sd > 0) {
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float p = Math.Min(1, sd / (softness * 2)) - 1;
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p = (sd - softness * (1 - p * p)) / td;
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tx -= p * tx;
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ty -= p * ty;
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dd = tx * tx + ty * ty;
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}
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}
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if (u) {
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l2 *= psx;
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float cos = (dd - l1 * l1 - l2 * l2) / (2 * l1 * l2);
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if (cos < -1) {
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cos = -1;
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a2 = MathUtils.PI * bendDir;
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} else if (cos > 1) {
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cos = 1;
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a2 = 0;
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if (stretch) {
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a = ((float)Math.Sqrt(dd) / (l1 + l2) - 1) * alpha + 1;
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sx *= a;
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if (uniform) sy *= a;
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}
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} else
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a2 = (float)Math.Acos(cos) * bendDir;
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a = l1 + l2 * cos;
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b = l2 * (float)Math.Sin(a2);
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a1 = (float)Math.Atan2(ty * a - tx * b, tx * a + ty * b);
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} else {
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a = psx * l2;
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b = psy * l2;
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float aa = a * a, bb = b * b, ta = (float)Math.Atan2(ty, tx);
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c = bb * l1 * l1 + aa * dd - aa * bb;
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float c1 = -2 * bb * l1, c2 = bb - aa;
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d = c1 * c1 - 4 * c2 * c;
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if (d >= 0) {
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float q = (float)Math.Sqrt(d);
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if (c1 < 0) q = -q;
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q = -(c1 + q) * 0.5f;
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float r0 = q / c2, r1 = c / q;
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float r = Math.Abs(r0) < Math.Abs(r1) ? r0 : r1;
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r0 = dd - r * r;
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if (r0 >= 0) {
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y = (float)Math.Sqrt(r0) * bendDir;
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a1 = ta - (float)Math.Atan2(y, r);
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a2 = (float)Math.Atan2(y / psy, (r - l1) / psx);
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goto break_outer; // break outer;
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}
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}
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float minAngle = MathUtils.PI, minX = l1 - a, minDist = minX * minX, minY = 0;
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float maxAngle = 0, maxX = l1 + a, maxDist = maxX * maxX, maxY = 0;
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c = -a * l1 / (aa - bb);
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if (c >= -1 && c <= 1) {
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c = (float)Math.Acos(c);
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x = a * (float)Math.Cos(c) + l1;
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y = b * (float)Math.Sin(c);
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d = x * x + y * y;
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if (d < minDist) {
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minAngle = c;
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minDist = d;
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minX = x;
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minY = y;
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}
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if (d > maxDist) {
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maxAngle = c;
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maxDist = d;
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maxX = x;
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maxY = y;
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}
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}
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if (dd <= (minDist + maxDist) * 0.5f) {
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a1 = ta - (float)Math.Atan2(minY * bendDir, minX);
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a2 = minAngle * bendDir;
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} else {
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a1 = ta - (float)Math.Atan2(maxY * bendDir, maxX);
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a2 = maxAngle * bendDir;
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}
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}
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break_outer:
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float os = (float)Math.Atan2(cy, cx) * s2;
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float rotation = parent.arotation;
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a1 = (a1 - os) * MathUtils.RadDeg + os1 - rotation;
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if (a1 > 180)
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a1 -= 360;
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else if (a1 < -180)
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a1 += 360;
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parent.UpdateWorldTransform(px, py, rotation + a1 * alpha, sx, sy, 0, 0);
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rotation = child.arotation;
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a2 = ((a2 + os) * MathUtils.RadDeg - child.ashearX) * s2 + os2 - rotation;
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if (a2 > 180)
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a2 -= 360;
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else if (a2 < -180)
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a2 += 360;
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child.UpdateWorldTransform(cx, cy, rotation + a2 * alpha, child.ascaleX, child.ascaleY, child.ashearX, child.ashearY);
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}
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}
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}
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