com.esotericsoftware.spine.IkConstraint Maven / Gradle / Ivy
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package com.esotericsoftware.spine;
import static com.esotericsoftware.spine.utils.SpineUtils.*;
import com.badlogic.gdx.utils.Array;
/** Stores the current pose for an IK constraint. An IK constraint adjusts the rotation of 1 or 2 constrained bones so the tip of
* the last bone is as close to the target bone as possible.
*
* See IK constraints in the Spine User Guide. */
public class IkConstraint implements Updatable {
final IkConstraintData data;
final Array bones;
Bone target;
int bendDirection;
boolean compress, stretch;
float mix = 1, softness;
boolean active;
public IkConstraint (IkConstraintData data, Skeleton skeleton) {
if (data == null) throw new IllegalArgumentException("data cannot be null.");
if (skeleton == null) throw new IllegalArgumentException("skeleton cannot be null.");
this.data = data;
mix = data.mix;
softness = data.softness;
bendDirection = data.bendDirection;
compress = data.compress;
stretch = data.stretch;
bones = new Array(data.bones.size);
for (BoneData boneData : data.bones)
bones.add(skeleton.findBone(boneData.name));
target = skeleton.findBone(data.target.name);
}
/** Copy constructor. */
public IkConstraint (IkConstraint constraint, Skeleton skeleton) {
if (constraint == null) throw new IllegalArgumentException("constraint cannot be null.");
if (skeleton == null) throw new IllegalArgumentException("skeleton cannot be null.");
data = constraint.data;
bones = new Array(constraint.bones.size);
for (Bone bone : constraint.bones)
bones.add(skeleton.bones.get(bone.data.index));
target = skeleton.bones.get(constraint.target.data.index);
mix = constraint.mix;
softness = constraint.softness;
bendDirection = constraint.bendDirection;
compress = constraint.compress;
stretch = constraint.stretch;
}
/** Applies the constraint to the constrained bones. */
public void apply () {
update();
}
public void update () {
Bone target = this.target;
Array bones = this.bones;
switch (bones.size) {
case 1:
apply(bones.first(), target.worldX, target.worldY, compress, stretch, data.uniform, mix);
break;
case 2:
apply(bones.first(), bones.get(1), target.worldX, target.worldY, bendDirection, stretch, softness, mix);
break;
}
}
/** The bones that will be modified by this IK constraint. */
public Array getBones () {
return bones;
}
/** The bone that is the IK target. */
public Bone getTarget () {
return target;
}
public void setTarget (Bone target) {
if (target == null) throw new IllegalArgumentException("target cannot be null.");
this.target = target;
}
/** A percentage (0-1) that controls the mix between the constrained and unconstrained rotations. */
public float getMix () {
return mix;
}
public void setMix (float mix) {
this.mix = mix;
}
/** For two bone IK, the distance from the maximum reach of the bones that rotation will slow. */
public float getSoftness () {
return softness;
}
public void setSoftness (float softness) {
this.softness = softness;
}
/** Controls the bend direction of the IK bones, either 1 or -1. */
public int getBendDirection () {
return bendDirection;
}
public void setBendDirection (int bendDirection) {
this.bendDirection = bendDirection;
}
/** When true and only a single bone is being constrained, if the target is too close, the bone is scaled to reach it. */
public boolean getCompress () {
return compress;
}
public void setCompress (boolean compress) {
this.compress = compress;
}
/** When true, if the target is out of range, the parent bone is scaled to reach it. If more than one bone is being constrained
* and the parent bone has local nonuniform scale, stretch is not applied. */
public boolean getStretch () {
return stretch;
}
public void setStretch (boolean stretch) {
this.stretch = stretch;
}
public boolean isActive () {
return active;
}
/** The IK constraint's setup pose data. */
public IkConstraintData getData () {
return data;
}
public String toString () {
return data.name;
}
/** Applies 1 bone IK. The target is specified in the world coordinate system. */
static public void apply (Bone bone, float targetX, float targetY, boolean compress, boolean stretch, boolean uniform,
float alpha) {
if (bone == null) throw new IllegalArgumentException("bone cannot be null.");
if (!bone.appliedValid) bone.updateAppliedTransform();
Bone p = bone.parent;
float pa = p.a, pb = p.b, pc = p.c, pd = p.d;
float rotationIK = -bone.ashearX - bone.arotation, tx, ty;
switch (bone.data.transformMode) {
case onlyTranslation:
tx = targetX - bone.worldX;
ty = targetY - bone.worldY;
break;
case noRotationOrReflection:
float s = Math.abs(pa * pd - pb * pc) / (pa * pa + pc * pc);
float sa = pa / bone.skeleton.scaleX;
float sc = pc / bone.skeleton.scaleY;
pb = -sc * s * bone.skeleton.scaleX;
pd = sa * s * bone.skeleton.scaleY;
rotationIK += atan2(sc, sa) * radDeg;
// Fall through.
default:
float x = targetX - p.worldX, y = targetY - p.worldY;
float d = pa * pd - pb * pc;
tx = (x * pd - y * pb) / d - bone.ax;
ty = (y * pa - x * pc) / d - bone.ay;
}
rotationIK += atan2(ty, tx) * radDeg;
if (bone.ascaleX < 0) rotationIK += 180;
if (rotationIK > 180)
rotationIK -= 360;
else if (rotationIK < -180) //
rotationIK += 360;
float sx = bone.ascaleX, sy = bone.ascaleY;
if (compress || stretch) {
switch (bone.data.transformMode) {
case noScale:
case noScaleOrReflection:
tx = targetX - bone.worldX;
ty = targetY - bone.worldY;
}
float b = bone.data.length * sx, dd = (float)Math.sqrt(tx * tx + ty * ty);
if ((compress && dd < b) || (stretch && dd > b) && b > 0.0001f) {
float s = (dd / b - 1) * alpha + 1;
sx *= s;
if (uniform) sy *= s;
}
}
bone.updateWorldTransform(bone.ax, bone.ay, bone.arotation + rotationIK * alpha, sx, sy, bone.ashearX, bone.ashearY);
}
/** Applies 2 bone IK. The target is specified in the world coordinate system.
* @param child A direct descendant of the parent bone. */
static public void apply (Bone parent, Bone child, float targetX, float targetY, int bendDir, boolean stretch, float softness,
float alpha) {
if (parent == null) throw new IllegalArgumentException("parent cannot be null.");
if (child == null) throw new IllegalArgumentException("child cannot be null.");
if (alpha == 0) {
child.updateWorldTransform();
return;
}
if (!parent.appliedValid) parent.updateAppliedTransform();
if (!child.appliedValid) child.updateAppliedTransform();
float px = parent.ax, py = parent.ay, psx = parent.ascaleX, sx = psx, psy = parent.ascaleY, csx = child.ascaleX;
int os1, os2, s2;
if (psx < 0) {
psx = -psx;
os1 = 180;
s2 = -1;
} else {
os1 = 0;
s2 = 1;
}
if (psy < 0) {
psy = -psy;
s2 = -s2;
}
if (csx < 0) {
csx = -csx;
os2 = 180;
} else
os2 = 0;
float cx = child.ax, cy, cwx, cwy, a = parent.a, b = parent.b, c = parent.c, d = parent.d;
boolean u = Math.abs(psx - psy) <= 0.0001f;
if (!u) {
cy = 0;
cwx = a * cx + parent.worldX;
cwy = c * cx + parent.worldY;
} else {
cy = child.ay;
cwx = a * cx + b * cy + parent.worldX;
cwy = c * cx + d * cy + parent.worldY;
}
Bone pp = parent.parent;
a = pp.a;
b = pp.b;
c = pp.c;
d = pp.d;
float id = 1 / (a * d - b * c), x = cwx - pp.worldX, y = cwy - pp.worldY;
float dx = (x * d - y * b) * id - px, dy = (y * a - x * c) * id - py;
float l1 = (float)Math.sqrt(dx * dx + dy * dy), l2 = child.data.length * csx, a1, a2;
if (l1 < 0.0001f) {
apply(parent, targetX, targetY, false, stretch, false, alpha);
child.updateWorldTransform(cx, cy, 0, child.ascaleX, child.ascaleY, child.ashearX, child.ashearY);
return;
}
x = targetX - pp.worldX;
y = targetY - pp.worldY;
float tx = (x * d - y * b) * id - px, ty = (y * a - x * c) * id - py;
float dd = tx * tx + ty * ty;
if (softness != 0) {
softness *= psx * (csx + 1) / 2;
float td = (float)Math.sqrt(dd), sd = td - l1 - l2 * psx + softness;
if (sd > 0) {
float p = Math.min(1, sd / (softness * 2)) - 1;
p = (sd - softness * (1 - p * p)) / td;
tx -= p * tx;
ty -= p * ty;
dd = tx * tx + ty * ty;
}
}
outer:
if (u) {
l2 *= psx;
float cos = (dd - l1 * l1 - l2 * l2) / (2 * l1 * l2);
if (cos < -1)
cos = -1;
else if (cos > 1) {
cos = 1;
if (stretch) sx *= ((float)Math.sqrt(dd) / (l1 + l2) - 1) * alpha + 1;
}
a2 = (float)Math.acos(cos) * bendDir;
a = l1 + l2 * cos;
b = l2 * sin(a2);
a1 = atan2(ty * a - tx * b, tx * a + ty * b);
} else {
a = psx * l2;
b = psy * l2;
float aa = a * a, bb = b * b, ta = atan2(ty, tx);
c = bb * l1 * l1 + aa * dd - aa * bb;
float c1 = -2 * bb * l1, c2 = bb - aa;
d = c1 * c1 - 4 * c2 * c;
if (d >= 0) {
float q = (float)Math.sqrt(d);
if (c1 < 0) q = -q;
q = -(c1 + q) / 2;
float r0 = q / c2, r1 = c / q;
float r = Math.abs(r0) < Math.abs(r1) ? r0 : r1;
if (r * r <= dd) {
y = (float)Math.sqrt(dd - r * r) * bendDir;
a1 = ta - atan2(y, r);
a2 = atan2(y / psy, (r - l1) / psx);
break outer;
}
}
float minAngle = PI, minX = l1 - a, minDist = minX * minX, minY = 0;
float maxAngle = 0, maxX = l1 + a, maxDist = maxX * maxX, maxY = 0;
c = -a * l1 / (aa - bb);
if (c >= -1 && c <= 1) {
c = (float)Math.acos(c);
x = a * cos(c) + l1;
y = b * sin(c);
d = x * x + y * y;
if (d < minDist) {
minAngle = c;
minDist = d;
minX = x;
minY = y;
}
if (d > maxDist) {
maxAngle = c;
maxDist = d;
maxX = x;
maxY = y;
}
}
if (dd <= (minDist + maxDist) / 2) {
a1 = ta - atan2(minY * bendDir, minX);
a2 = minAngle * bendDir;
} else {
a1 = ta - atan2(maxY * bendDir, maxX);
a2 = maxAngle * bendDir;
}
}
float os = atan2(cy, cx) * s2;
float rotation = parent.arotation;
a1 = (a1 - os) * radDeg + os1 - rotation;
if (a1 > 180)
a1 -= 360;
else if (a1 < -180) a1 += 360;
parent.updateWorldTransform(px, py, rotation + a1 * alpha, sx, parent.ascaleY, 0, 0);
rotation = child.arotation;
a2 = ((a2 + os) * radDeg - child.ashearX) * s2 + os2 - rotation;
if (a2 > 180)
a2 -= 360;
else if (a2 < -180) a2 += 360;
child.updateWorldTransform(cx, cy, rotation + a2 * alpha, child.ascaleX, child.ascaleY, child.ashearX, child.ashearY);
}
}