[libgdx] Added a Physics enum to updateWorldTransform and Updateable#update to control how physics and other non-deterministic updates are applied.

spine-libgdx/spine-libgdx-tests/src/com/esotericsoftware/spine/BonePlotting.java

@@ -34,6 +34,7 @@ import com.badlogic.gdx.utils.Null;
 
 import com.esotericsoftware.spine.Animation.MixBlend;
 import com.esotericsoftware.spine.Animation.MixDirection;
+import com.esotericsoftware.spine.Skeleton.Physics;
 import com.esotericsoftware.spine.attachments.AttachmentLoader;
 import com.esotericsoftware.spine.attachments.BoundingBoxAttachment;
 import com.esotericsoftware.spine.attachments.ClippingAttachment;
@@ -83,7 +84,7 @@ public class BonePlotting {
 			float time = 0;
 			while (time < animation.getDuration()) {
 				animation.apply(skeleton, time, time, false, null, 1, MixBlend.first, MixDirection.in);
-				skeleton.updateWorldTransform();
+				skeleton.updateWorldTransform(Physics.update);
 
 				System.out.println(animation.getName() + "," //
 					+ bone.getWorldX() + "," + bone.getWorldY() + "," + bone.getWorldRotationX());

spine-libgdx/spine-libgdx-tests/src/com/esotericsoftware/spine/Box2DExample.java

@@ -54,6 +54,7 @@ import com.badlogic.gdx.utils.ScreenUtils;
 
 import com.esotericsoftware.spine.Animation.MixBlend;
 import com.esotericsoftware.spine.Animation.MixDirection;
+import com.esotericsoftware.spine.Skeleton.Physics;
 import com.esotericsoftware.spine.attachments.AtlasAttachmentLoader;
 import com.esotericsoftware.spine.attachments.RegionAttachment;
 import com.esotericsoftware.spine.attachments.Sequence;
@@ -104,7 +105,7 @@ public class Box2DExample extends ApplicationAdapter {
 		skeleton = new Skeleton(skeletonData);
 		skeleton.x = -32;
 		skeleton.y = 1;
-		skeleton.updateWorldTransform();
+		skeleton.updateWorldTransform(Physics.update);
 
 		// See Box2DTest in libgdx for more detailed information about Box2D setup.
 		camera = new OrthographicCamera(48, 32);
@@ -150,7 +151,7 @@ public class Box2DExample extends ApplicationAdapter {
 
 		animation.apply(skeleton, time, time, true, events, 1, MixBlend.first, MixDirection.in);
 		skeleton.x += 8 * delta;
-		skeleton.updateWorldTransform();
+		skeleton.updateWorldTransform(Physics.update);
 		skeletonRenderer.draw(batch, skeleton);
 
 		batch.end();

spine-libgdx/spine-libgdx-tests/src/com/esotericsoftware/spine/FboTest.java

@@ -42,6 +42,7 @@ import com.badlogic.gdx.graphics.g2d.TextureRegion;
 import com.badlogic.gdx.graphics.glutils.FrameBuffer;
 import com.badlogic.gdx.utils.ScreenUtils;
 
+import com.esotericsoftware.spine.Skeleton.Physics;
 import com.esotericsoftware.spine.utils.TwoColorPolygonBatch;
 
 /** Demonstrates rendering an animation to a frame buffer (FBO) and then rendering the FBO to the screen. */
@@ -75,7 +76,7 @@ public class FboTest extends ApplicationAdapter {
 		// Create a skeleton instance, set the position of its root bone, and update its world transform.
 		skeleton = new Skeleton(skeletonData);
 		skeleton.setPosition(250, 20);
-		skeleton.updateWorldTransform();
+		skeleton.updateWorldTransform(Physics.update);
 
 		// Create an FBO and a texture region with Y flipped.
 		fbo = new FrameBuffer(Pixmap.Format.RGBA8888, 512, 512, false);

spine-libgdx/spine-libgdx-tests/src/com/esotericsoftware/spine/IKTest.java

@@ -38,6 +38,7 @@ import com.badlogic.gdx.math.Vector2;
 import com.badlogic.gdx.math.Vector3;
 import com.badlogic.gdx.utils.ScreenUtils;
 
+import com.esotericsoftware.spine.Skeleton.Physics;
 import com.esotericsoftware.spine.utils.TwoColorPolygonBatch;
 
 /** Demonstrates how to let the target bone of an IK constraint follow the mouse or touch position, which in turn repositions part
@@ -97,7 +98,7 @@ public class IKTest extends ApplicationAdapter {
 		// later.
 		state.update(Gdx.graphics.getDeltaTime());
 		state.apply(skeleton);
-		skeleton.updateWorldTransform();
+		skeleton.updateWorldTransform(Physics.update);
 
 		// Position the "crosshair" bone at the mouse
 		// location. We do this before calling
@@ -122,7 +123,7 @@ public class IKTest extends ApplicationAdapter {
 		// Calculate final world transform with the
 		// crosshair bone set to the mouse cursor
 		// position.
-		skeleton.updateWorldTransform();
+		skeleton.updateWorldTransform(Physics.update);
 
 		// Clear the screen, update the camera and
 		// render the skeleton.

spine-libgdx/spine-libgdx-tests/src/com/esotericsoftware/spine/MixAndMatchTest.java

@@ -37,6 +37,8 @@ import com.badlogic.gdx.graphics.g2d.PolygonSpriteBatch;
 import com.badlogic.gdx.graphics.g2d.TextureAtlas;
 import com.badlogic.gdx.utils.ScreenUtils;
 
+import com.esotericsoftware.spine.Skeleton.Physics;
+
 /** Demonstrates creating and configuring a new skin at runtime. */
 public class MixAndMatchTest extends ApplicationAdapter {
 	OrthographicCamera camera;
@@ -92,7 +94,7 @@ public class MixAndMatchTest extends ApplicationAdapter {
 		ScreenUtils.clear(0, 0, 0, 0);
 
 		state.apply(skeleton); // Poses skeleton using current animations. This sets the bones' local SRT.
-		skeleton.updateWorldTransform(); // Uses the bones' local SRT to compute their world SRT.
+		skeleton.updateWorldTransform(Physics.update); // Uses the bones' local SRT to compute their world SRT.
 
 		// Configure the camera, and PolygonSpriteBatch
 		camera.update();

spine-libgdx/spine-libgdx-tests/src/com/esotericsoftware/spine/NormalMapTest.java

@@ -58,6 +58,7 @@ import com.badlogic.gdx.utils.ScreenUtils;
 
 import com.esotericsoftware.spine.Animation.MixBlend;
 import com.esotericsoftware.spine.Animation.MixDirection;
+import com.esotericsoftware.spine.Skeleton.Physics;
 
 /** Demonstrates simplistic usage of lighting with normal maps.
  * <p>
@@ -110,7 +111,7 @@ public class NormalMapTest extends ApplicationAdapter {
 		skeleton = new Skeleton(skeleton);
 		skeleton.setX(ui.prefs.getFloat("x", Gdx.graphics.getWidth() / 2));
 		skeleton.setY(ui.prefs.getFloat("y", Gdx.graphics.getHeight() / 4));
-		skeleton.updateWorldTransform();
+		skeleton.updateWorldTransform(Physics.update);
 
 		Gdx.input.setInputProcessor(new InputMultiplexer(ui.stage, new InputAdapter() {
 			public boolean touchDown (int screenX, int screenY, int pointer, int button) {
@@ -136,7 +137,7 @@ public class NormalMapTest extends ApplicationAdapter {
 		float lastTime = time;
 		time += Gdx.graphics.getDeltaTime();
 		if (animation != null) animation.apply(skeleton, lastTime, time, true, null, 1, MixBlend.first, MixDirection.in);
-		skeleton.updateWorldTransform();
+		skeleton.updateWorldTransform(Physics.update);
 
 		lightPosition.x = Gdx.input.getX();
 		lightPosition.y = (Gdx.graphics.getHeight() - 1 - Gdx.input.getY());

spine-libgdx/spine-libgdx-tests/src/com/esotericsoftware/spine/PngExportTest.java

@@ -48,6 +48,7 @@ import com.badlogic.gdx.utils.ScreenUtils;
 
 import com.esotericsoftware.spine.Animation.MixBlend;
 import com.esotericsoftware.spine.Animation.MixDirection;
+import com.esotericsoftware.spine.Skeleton.Physics;
 import com.esotericsoftware.spine.utils.TwoColorPolygonBatch;
 
 /** Demonstrates rendering an animation to a frame buffer (FBO) and then writing each frame as a PNG. */
@@ -81,7 +82,7 @@ public class PngExportTest extends ApplicationAdapter {
 		// Create a skeleton instance, set the position of its root bone, and update its world transform.
 		skeleton = new Skeleton(skeletonData);
 		skeleton.setPosition(250, 20);
-		skeleton.updateWorldTransform();
+		skeleton.updateWorldTransform(Physics.update);
 
 		// Create an FBO and a texture region.
 		fbo = new FrameBuffer(Pixmap.Format.RGBA8888, 512, 512, false);
@@ -104,7 +105,7 @@ public class PngExportTest extends ApplicationAdapter {
 		int frame = 1;
 		while (time < animation.getDuration()) {
 			animation.apply(skeleton, time, time, false, null, 1, MixBlend.first, MixDirection.in);
-			skeleton.updateWorldTransform();
+			skeleton.updateWorldTransform(Physics.update);
 
 			// Render the skeleton to the FBO.
 			ScreenUtils.clear(0, 0, 0, 0);

spine-libgdx/spine-libgdx-tests/src/com/esotericsoftware/spine/SimpleTest1.java

@@ -36,6 +36,7 @@ import com.badlogic.gdx.graphics.GL20;
 import com.badlogic.gdx.graphics.OrthographicCamera;
 import com.badlogic.gdx.graphics.g2d.TextureAtlas;
 
+import com.esotericsoftware.spine.Skeleton.Physics;
 import com.esotericsoftware.spine.utils.TwoColorPolygonBatch;
 
 /** Demonstrates loading, animating, and rendering a skeleton.
@@ -86,7 +87,7 @@ public class SimpleTest1 extends ApplicationAdapter {
 		Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
 
 		state.apply(skeleton); // Poses skeleton using current animations. This sets the bones' local SRT.
-		skeleton.updateWorldTransform(); // Uses the bones' local SRT to compute their world SRT.
+		skeleton.updateWorldTransform(Physics.update); // Uses the bones' local SRT to compute their world SRT.
 
 		// Configure the camera, SpriteBatch, and SkeletonRendererDebug.
 		camera.update();

spine-libgdx/spine-libgdx-tests/src/com/esotericsoftware/spine/SimpleTest2.java

@@ -41,6 +41,7 @@ import com.badlogic.gdx.math.Vector3;
 
 import com.esotericsoftware.spine.AnimationState.AnimationStateListener;
 import com.esotericsoftware.spine.AnimationState.TrackEntry;
+import com.esotericsoftware.spine.Skeleton.Physics;
 import com.esotericsoftware.spine.attachments.BoundingBoxAttachment;
 import com.esotericsoftware.spine.utils.TwoColorPolygonBatch;
 
@@ -147,7 +148,7 @@ public class SimpleTest2 extends ApplicationAdapter {
 		Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
 
 		if (state.apply(skeleton)) // Poses skeleton using current animations. This sets the bones' local SRT.
-			skeleton.updateWorldTransform(); // Uses the bones' local SRT to compute their world SRT.
+			skeleton.updateWorldTransform(Physics.update); // Uses the bones' local SRT to compute their world SRT.
 
 		// Configure the camera, SpriteBatch, and SkeletonRendererDebug.
 		camera.update();

spine-libgdx/spine-libgdx-tests/src/com/esotericsoftware/spine/SimpleTest3.java

@@ -37,6 +37,8 @@ import com.badlogic.gdx.graphics.g2d.PolygonSpriteBatch;
 import com.badlogic.gdx.graphics.g2d.TextureAtlas;
 import com.badlogic.gdx.utils.ScreenUtils;
 
+import com.esotericsoftware.spine.Skeleton.Physics;
+
 /** Demonstrates applying multiple animations at once using {@link AnimationState} tracks. */
 public class SimpleTest3 extends ApplicationAdapter {
 	OrthographicCamera camera;
@@ -84,7 +86,7 @@ public class SimpleTest3 extends ApplicationAdapter {
 		ScreenUtils.clear(0, 0, 0, 0);
 
 		if (state.apply(skeleton)) // Poses skeleton using current animations. This sets the bones' local SRT.
-			skeleton.updateWorldTransform(); // Uses the bones' local SRT to compute their world SRT.
+			skeleton.updateWorldTransform(Physics.update); // Uses the bones' local SRT to compute their world SRT.
 
 		// Configure the camera, SpriteBatch, and SkeletonRendererDebug.
 		camera.update();

spine-libgdx/spine-libgdx-tests/src/com/esotericsoftware/spine/SkeletonAssetManagerTest.java

@@ -38,6 +38,7 @@ import com.badlogic.gdx.graphics.g2d.PolygonSpriteBatch;
 import com.badlogic.gdx.graphics.g2d.TextureAtlas;
 import com.badlogic.gdx.utils.ScreenUtils;
 
+import com.esotericsoftware.spine.Skeleton.Physics;
 import com.esotericsoftware.spine.utils.SkeletonDataLoader;
 import com.esotericsoftware.spine.utils.SkeletonDataLoader.SkeletonDataParameter;
 
@@ -102,7 +103,7 @@ public class SkeletonAssetManagerTest extends ApplicationAdapter {
 		state.update(Gdx.graphics.getDeltaTime()); // Update the animation time.
 
 		state.apply(skeleton); // Poses skeleton using current animations. This sets the bones' local SRT.
-		skeleton.updateWorldTransform(); // Uses the bones' local SRT to compute their world SRT.
+		skeleton.updateWorldTransform(Physics.update); // Uses the bones' local SRT to compute their world SRT.
 
 		// Configure the camera, SpriteBatch, and SkeletonRendererDebug.
 		camera.update();

spine-libgdx/spine-libgdx-tests/src/com/esotericsoftware/spine/SkeletonAttachmentTest.java

@@ -37,6 +37,7 @@ import com.badlogic.gdx.graphics.g2d.PolygonSpriteBatch;
 import com.badlogic.gdx.graphics.g2d.TextureAtlas;
 import com.badlogic.gdx.utils.ScreenUtils;
 
+import com.esotericsoftware.spine.Skeleton.Physics;
 import com.esotericsoftware.spine.attachments.SkeletonAttachment;
 
 /** Demonstrates using {@link SkeletonAttachment} to use an entire skeleton as an attachment. */
@@ -93,11 +94,11 @@ public class SkeletonAttachmentTest extends ApplicationAdapter {
 	public void render () {
 		spineboyState.update(Gdx.graphics.getDeltaTime());
 		spineboyState.apply(spineboy);
-		spineboy.updateWorldTransform();
+		spineboy.updateWorldTransform(Physics.update);
 
 		goblinState.update(Gdx.graphics.getDeltaTime());
 		goblinState.apply(goblin);
-		goblin.updateWorldTransform(attachmentBone);
+		goblin.updateWorldTransform(Physics.update, attachmentBone);
 
 		ScreenUtils.clear(0, 0, 0, 0);
 

spine-libgdx/spine-libgdx-tests/src/com/esotericsoftware/spine/TestHarness.java

@@ -39,6 +39,8 @@ import com.badlogic.gdx.graphics.g2d.TextureAtlas;
 import com.badlogic.gdx.graphics.glutils.ShapeRenderer;
 import com.badlogic.gdx.utils.ScreenUtils;
 
+import com.esotericsoftware.spine.Skeleton.Physics;
+
 /** Boilerplate for basic skeleton rendering, used for various testing. */
 public class TestHarness extends ApplicationAdapter {
 // static String JSON = "coin/coin-pro.json";
@@ -79,7 +81,7 @@ public class TestHarness extends ApplicationAdapter {
 		// state.setAnimation(0, "rotate", false);
 		state.update(0);
 		state.apply(skeleton);
-		skeleton.updateWorldTransform();
+		skeleton.updateWorldTransform(Physics.update);
 	}
 
 	public void render () {
@@ -87,7 +89,7 @@ public class TestHarness extends ApplicationAdapter {
 			state.update(0.25f); // Update the animation time.
 		}
 		state.apply(skeleton); // Poses skeleton using current animations. This sets the bones' local SRT.
-		skeleton.updateWorldTransform(); // Uses the bones' local SRT to compute their world SRT.
+		skeleton.updateWorldTransform(Physics.update); // Uses the bones' local SRT to compute their world SRT.
 
 		ScreenUtils.clear(0, 0, 0, 0);
 

spine-libgdx/spine-libgdx-tests/src/com/esotericsoftware/spine/TimelineApiTest.java

@@ -39,6 +39,7 @@ import com.badlogic.gdx.utils.ScreenUtils;
 
 import com.esotericsoftware.spine.Animation.MixBlend;
 import com.esotericsoftware.spine.Animation.MixDirection;
+import com.esotericsoftware.spine.Skeleton.Physics;
 
 /** Demonstrates using the timeline API. See {@link SimpleTest1} for a higher level API using {@link AnimationState}.
  * <p>
@@ -79,7 +80,7 @@ public class TimelineApiTest extends ApplicationAdapter {
 		jumpAnimation = skeletonData.findAnimation("jump");
 
 		skeleton = new Skeleton(skeletonData);
-		skeleton.updateWorldTransform();
+		skeleton.updateWorldTransform(Physics.update);
 		skeleton.setPosition(-50, 20);
 	}
 
@@ -127,7 +128,7 @@ public class TimelineApiTest extends ApplicationAdapter {
 			walkAnimation.apply(skeleton, time, time, true, events, 1, MixBlend.first, MixDirection.in);
 		}
 
-		skeleton.updateWorldTransform();
+		skeleton.updateWorldTransform(Physics.update);
 
 		batch.begin();
 		renderer.draw(batch, skeleton);

spine-libgdx/spine-libgdx/src/com/esotericsoftware/spine/Bone.java

@@ -38,6 +38,7 @@ import com.badlogic.gdx.utils.Array;
 import com.badlogic.gdx.utils.Null;
 
 import com.esotericsoftware.spine.BoneData.TransformMode;
+import com.esotericsoftware.spine.Skeleton.Physics;
 
 /** Stores a bone's current pose.
  * <p>
@@ -82,7 +83,7 @@ public class Bone implements Updatable {
 	}
 
 	/** Computes the world transform using the parent bone and this bone's local applied transform. */
-	public void update () {
+	public void update (Physics physics) {
 		updateWorldTransform(ax, ay, arotation, ascaleX, ascaleY, ashearX, ashearY);
 	}
 
@@ -618,8 +619,8 @@ public class Bone implements Updatable {
 
 	/** Rotates the world transform the specified amount.
 	 * <p>
-	 * After changes are made to the world transform, {@link #updateAppliedTransform()} should be called and {@link #update()} will
-	 * need to be called on any child bones, recursively. */
+	 * After changes are made to the world transform, {@link #updateAppliedTransform()} should be called and
+	 * {@link #update(Physics)} will need to be called on any child bones, recursively. */
 	public void rotateWorld (float degrees) {
 		degrees *= degRad;
 		float sin = sin(degrees), cos = cos(degrees);

spine-libgdx/spine-libgdx/src/com/esotericsoftware/spine/BoneData.java

@@ -32,6 +32,8 @@ package com.esotericsoftware.spine;
 import com.badlogic.gdx.graphics.Color;
 import com.badlogic.gdx.utils.Null;
 
+import com.esotericsoftware.spine.Skeleton.Physics;
+
 /** Stores the setup pose for a {@link Bone}. */
 public class BoneData {
 	final int index;
@@ -175,8 +177,8 @@ public class BoneData {
 		this.transformMode = transformMode;
 	}
 
-	/** When true, {@link Skeleton#updateWorldTransform()} only updates this bone if the {@link Skeleton#getSkin()} contains this
-	 * bone.
+	/** When true, {@link Skeleton#updateWorldTransform(Physics)} only updates this bone if the {@link Skeleton#getSkin()} contains
+	 * this bone.
 	 * <p>
 	 * See {@link Skin#getBones()}. */
 	public boolean getSkinRequired () {

spine-libgdx/spine-libgdx/src/com/esotericsoftware/spine/ConstraintData.java

@@ -29,6 +29,8 @@
 
 package com.esotericsoftware.spine;
 
+import com.esotericsoftware.spine.Skeleton.Physics;
+
 /** The base class for all constraint datas. */
 abstract public class ConstraintData {
 	final String name;
@@ -46,7 +48,7 @@ abstract public class ConstraintData {
 	}
 
 	/** The ordinal of this constraint for the order a skeleton's constraints will be applied by
-	 * {@link Skeleton#updateWorldTransform()}. */
+	 * {@link Skeleton#updateWorldTransform(Physics)}. */
 	public int getOrder () {
 		return order;
 	}
@@ -55,8 +57,8 @@ abstract public class ConstraintData {
 		this.order = order;
 	}
 
-	/** When true, {@link Skeleton#updateWorldTransform()} only updates this constraint if the {@link Skeleton#getSkin()} contains
-	 * this constraint.
+	/** When true, {@link Skeleton#updateWorldTransform(Physics)} only updates this constraint if the {@link Skeleton#getSkin()}
+	 * contains this constraint.
 	 * <p>
 	 * See {@link Skin#getConstraints()}. */
 	public boolean getSkinRequired () {

spine-libgdx/spine-libgdx/src/com/esotericsoftware/spine/IkConstraint.java

@@ -33,6 +33,8 @@ import static com.esotericsoftware.spine.utils.SpineUtils.*;
 
 import com.badlogic.gdx.utils.Array;
 
+import com.esotericsoftware.spine.Skeleton.Physics;
+
 /** 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.
  * <p>
@@ -87,7 +89,7 @@ public class IkConstraint implements Updatable {
 	}
 
 	/** Applies the constraint to the constrained bones. */
-	public void update () {
+	public void update (Physics physics) {
 		if (mix == 0) return;
 		Bone target = this.target;
 		Object[] bones = this.bones.items;

spine-libgdx/spine-libgdx/src/com/esotericsoftware/spine/PathConstraint.java

@@ -39,6 +39,7 @@ import com.badlogic.gdx.utils.FloatArray;
 import com.esotericsoftware.spine.PathConstraintData.PositionMode;
 import com.esotericsoftware.spine.PathConstraintData.RotateMode;
 import com.esotericsoftware.spine.PathConstraintData.SpacingMode;
+import com.esotericsoftware.spine.Skeleton.Physics;
 import com.esotericsoftware.spine.attachments.Attachment;
 import com.esotericsoftware.spine.attachments.PathAttachment;
 
@@ -101,7 +102,7 @@ public class PathConstraint implements Updatable {
 	}
 
 	/** Applies the constraint to the constrained bones. */
-	public void update () {
+	public void update (Physics physics) {
 		Attachment attachment = target.attachment;
 		if (!(attachment instanceof PathAttachment)) return;
 

spine-libgdx/spine-libgdx/src/com/esotericsoftware/spine/PhysicsConstraint.java

@@ -29,14 +29,23 @@
 
 package com.esotericsoftware.spine;
 
+import static com.badlogic.gdx.math.Interpolation.*;
+import static com.esotericsoftware.spine.utils.SpineUtils.*;
+
+import com.badlogic.gdx.math.Vector2;
 import com.badlogic.gdx.utils.Array;
 
+import com.esotericsoftware.spine.Skeleton.Physics;
+
+// BOZO - Physics steps/something in metrics view.
+
 /** Stores the current pose for a physics constraint. A physics constraint applies physics to bones.
  * <p>
  * See <a href="http://esotericsoftware.com/spine-physics-constraints">Physics constraints</a> in the Spine User Guide. */
 public class PhysicsConstraint implements Updatable {
 	final PhysicsConstraintData data;
 	final Array<Bone> bones;
+	State[] states = {};
 	float mix;
 
 	boolean active;
@@ -66,19 +75,158 @@ public class PhysicsConstraint implements Updatable {
 		mix = constraint.mix;
 	}
 
-	public void setToSetupPose () {
+	/** Caches information about bones. Must be called if {@link PathConstraintData#getBones()} is modified. */
+	public void updateBones () {
+		int count = 0;
+		if (data.x) count = 1;
+		if (data.y) count++;
+		if (data.rotate) count++;
+		if (data.scaleX) count++;
+		if (data.shearX) count++;
+		count *= bones.size * 2;
+		if (states.length != count) {
+			states = new State[count];
+			for (int i = 0; i < count; i++)
+				states[i] = new State();
+		}
+	}
+
+	public void reset () {
 		remaining = 0;
 		lastTime = skeleton.time;
 
+		for (int i = 0, n = states.length; i < n; i++) {
+			State state = states[i];
+			state.last = false;
+			state.offset = 0;
+			state.velocity = 0;
+		}
+	}
+
+	public void setToSetupPose () {
+		reset();
+
 		PhysicsConstraintData data = this.data;
 		mix = data.mix;
 	}
 
 	/** Applies the constraint to the constrained bones. */
-	public void update () {
+	public void update (Physics physics) {
 		if (mix == 0) return;
 
-		// BOZO
+		data.rotate = true; // BOZO - Remove.
+		updateBones(); // BOZO - Remove.
+
+		Object[] bones = this.bones.items;
+		int boneCount = this.bones.size;
+
+		switch (physics) {
+		case none:
+			return;
+		case reset:
+			reset();
+			// Fall through.
+		case update:
+			for (int i = 0; i < boneCount; i++) {
+				Bone bone = (Bone)bones[i];
+				if (data.rotate) {
+					Vector2 tip = bone.localToWorld(new Vector2(bone.data.length, 0));
+					State state = states[i];
+					if (!state.last)
+						state.last = true;
+					else if (state.x != bone.worldX || state.y != bone.worldY) {
+						float angleToOldTip = new Vector2(state.tipx, state.tipy).sub(bone.worldX, bone.worldY).angleDeg()
+							+ state.offset - bone.getWorldRotationX();
+						angleToOldTip -= (16384 - (int)(16384.499999999996 - angleToOldTip / 360)) * 360;
+						state.offset = linear.apply(0, angleToOldTip, data.inertia);
+// if (angleToOldTip > 0.0001f || angleToOldTip < -0.0001f) //
+// System.out.println(angleToOldTip);
+// if (applyShear) {
+// if (rotationOffset > 0)
+// rotationOffset = Math.max(0, rotationOffset - shearOffset);
+// else
+// rotationOffset = Math.min(0, rotationOffset - shearOffset);
+// }
+					}
+					tip = bone.localToWorld(new Vector2(bone.data.length, 0));
+// if (bone.worldX!=271.64316f)
+// System.out.println(bone.worldX);
+					if (bone.worldY != 662.5888f) System.out.println(bone.worldY);
+// System.out.println(bone.worldY);
+					state.x = bone.worldX;
+					state.y = bone.worldY;
+					state.tipx = tip.x;
+					state.tipy = tip.y;
+				}
+				// BOZO - Update physics x, y, scaleX, shearX.
+			}
+		}
+
+		boolean angle = data.rotate || data.scaleX || data.shearX;
+
+		remaining += Math.max(skeleton.time - lastTime, 0);
+		lastTime = skeleton.time;
+
+		float step = 0.016f; // BOZO - Keep fixed step? Make it configurable?
+		float cos = 0, sin = 0;
+		while (remaining >= step) {
+			remaining -= step;
+
+			for (int i = 0; i < boneCount; i++) {
+				Bone bone = (Bone)bones[i];
+				if (angle) {
+					float r = bone.getWorldRotationX() * degRad;
+					cos = (float)Math.cos(r);
+					sin = (float)Math.sin(r);
+				}
+				if (data.rotate) {
+					State state = states[i];
+					// BOZO - Keep length affecting rotation? Calculate world length?
+					float windForce = bone.data.length * 0.5f * (-data.wind * sin - data.gravity * cos);
+					float springForce = state.offset * data.strength;
+					float frictionForce = data.friction * state.velocity;
+					state.velocity += (windForce - springForce - frictionForce) / data.mass;
+					state.offset += state.velocity * step;
+					state.velocity *= data.damping;
+				}
+			}
+		}
+
+		if (mix == 1) {
+			for (int i = 0; i < boneCount; i++) {
+				Bone bone = (Bone)bones[i];
+				if (angle) {
+					float r = bone.getWorldRotationX() * degRad;
+					cos = (float)Math.cos(r);
+					sin = (float)Math.sin(r);
+				}
+				if (data.rotate) {
+					State state = states[i];
+					bone.rotateWorld(state.offset);
+					bone.updateAppliedTransform();
+				}
+			}
+		} else {
+			// BOZO - PhysicsConstraint mix.
+		}
+	}
+
+	public void step () {
+		// BOZO - PhysicsConstraint#step.
+	}
+
+	/** The bones that will be modified by this physics constraint. */
+	public Array<Bone> getBones () {
+		return bones;
+	}
+
+	/** A percentage (0-1) that controls the mix between the constrained and unconstrained poses. */
+	public float getMix () {
+		return mix;
+	}
+
+	public void setMix (float mix) {
+		this.mix = mix;
 	}
 
 	public boolean isActive () {
@@ -93,4 +241,9 @@ public class PhysicsConstraint implements Updatable {
 	public String toString () {
 		return data.name;
 	}
+
+	static class State {
+		boolean last;
+		float x, y, tipx, tipy, offset, velocity;
+	}
 }

spine-libgdx/spine-libgdx/src/com/esotericsoftware/spine/PhysicsConstraintData.java

@@ -36,9 +36,9 @@ import com.badlogic.gdx.utils.Array;
  * See <a href="http://esotericsoftware.com/spine-physics-constraints">Physics constraints</a> in the Spine User Guide. */
 public class PhysicsConstraintData extends ConstraintData {
 	final Array<BoneData> bones = new Array();
-	float speed = 1, mass = 1;
+	float speed = 1, mass = 1; // BOZO - Keep speed?
 	float strength, friction, damping, inertia, wind, gravity, mix;
-	boolean translate, rotate, scale, shear;
+	boolean x, y, rotate, scaleX, shearX;
 
 	public PhysicsConstraintData (String name) {
 		super(name);
@@ -113,12 +113,20 @@ public class PhysicsConstraintData extends ConstraintData {
 		this.gravity = gravity;
 	}
 
-	public boolean getTranslate () {
-		return translate;
+	public boolean getX () {
+		return x;
 	}
 
-	public void setTranslate (boolean translate) {
-		this.translate = translate;
+	public void setX (boolean x) {
+		this.x = x;
+	}
+
+	public boolean getY () {
+		return y;
+	}
+
+	public void setY (boolean y) {
+		this.y = y;
 	}
 
 	public boolean getRotate () {
@@ -129,20 +137,20 @@ public class PhysicsConstraintData extends ConstraintData {
 		this.rotate = rotate;
 	}
 
-	public boolean getScale () {
-		return scale;
+	public boolean getScaleX () {
+		return scaleX;
 	}
 
-	public void setScale (boolean scale) {
-		this.scale = scale;
+	public void setScaleX (boolean scaleX) {
+		this.scaleX = scaleX;
 	}
 
-	public boolean getShear () {
-		return shear;
+	public boolean getShearX () {
+		return shearX;
 	}
 
-	public void setShear (boolean shear) {
-		this.shear = shear;
+	public void setShearX (boolean shearX) {
+		this.shearX = shearX;
 	}
 
 	/** A percentage (0-1) that controls the mix between the constrained and unconstrained poses. */

spine-libgdx/spine-libgdx/src/com/esotericsoftware/spine/Skeleton.java

@@ -384,7 +384,7 @@ public class Skeleton {
 	 * <p>
 	 * See <a href="http://esotericsoftware.com/spine-runtime-skeletons#World-transforms">World transforms</a> in the Spine
 	 * Runtimes Guide. */
-	public void updateWorldTransform () {
+	public void updateWorldTransform (Physics physics) {
 		Object[] bones = this.bones.items;
 		for (int i = 0, n = this.bones.size; i < n; i++) {
 			Bone bone = (Bone)bones[i];
@@ -399,7 +399,7 @@ public class Skeleton {
 
 		Object[] updateCache = this.updateCache.items;
 		for (int i = 0, n = this.updateCache.size; i < n; i++)
-			((Updatable)updateCache[i]).update();
+			((Updatable)updateCache[i]).update(physics);
 	}
 
 	/** Temporarily sets the root bone as a child of the specified bone, then updates the world transform for each bone and applies
@@ -407,7 +407,7 @@ public class Skeleton {
 	 * <p>
 	 * See <a href="http://esotericsoftware.com/spine-runtime-skeletons#World-transforms">World transforms</a> in the Spine
 	 * Runtimes Guide. */
-	public void updateWorldTransform (Bone parent) {
+	public void updateWorldTransform (Physics physics, Bone parent) {
 		if (parent == null) throw new IllegalArgumentException("parent cannot be null.");
 
 		Object[] bones = this.bones.items;
@@ -443,7 +443,7 @@ public class Skeleton {
 		Object[] updateCache = this.updateCache.items;
 		for (int i = 0, n = this.updateCache.size; i < n; i++) {
 			Updatable updatable = (Updatable)updateCache[i];
-			if (updatable != rootBone) updatable.update();
+			if (updatable != rootBone) updatable.update(physics);
 		}
 	}
 
@@ -833,4 +833,19 @@ public class Skeleton {
 	public String toString () {
 		return data.name != null ? data.name : super.toString();
 	}
+
+	/** Determines how physics and other non-deterministic updates are applied. */
+	static public enum Physics {
+		/** Physics are not updated or applied. */
+		none,
+
+		/** Physics are not updated but the pose from physics is applied. */
+		pose,
+
+		/** Physics are updated and the pose from physics is applied. */
+		update,
+
+		/** Physics are reset to the current pose. */
+		reset
+	}
 }

spine-libgdx/spine-libgdx/src/com/esotericsoftware/spine/TransformConstraint.java

@@ -34,6 +34,8 @@ import static com.esotericsoftware.spine.utils.SpineUtils.*;
 import com.badlogic.gdx.math.Vector2;
 import com.badlogic.gdx.utils.Array;
 
+import com.esotericsoftware.spine.Skeleton.Physics;
+
 /** Stores the current pose for a transform constraint. A transform constraint adjusts the world transform of the constrained
  * bones to match that of the target bone.
  * <p>
@@ -90,7 +92,7 @@ public class TransformConstraint implements Updatable {
 	}
 
 	/** Applies the constraint to the constrained bones. */
-	public void update () {
+	public void update (Physics physics) {
 		if (mixRotate == 0 && mixX == 0 && mixY == 0 && mixScaleX == 0 && mixScaleY == 0 && mixShearY == 0) return;
 		if (data.local) {
 			if (data.relative)

spine-libgdx/spine-libgdx/src/com/esotericsoftware/spine/Updatable.java

@@ -29,9 +29,12 @@
 
 package com.esotericsoftware.spine;
 
-/** The interface for items updated by {@link Skeleton#updateWorldTransform()}. */
+import com.esotericsoftware.spine.Skeleton.Physics;
+
+/** The interface for items updated by {@link Skeleton#updateWorldTransform(Physics)}. */
 public interface Updatable {
-	public void update ();
+	/** @param physics Determines how physics and other non-deterministic updates are applied. */
+	public void update (Physics physics);
 
 	/** Returns false when this item has not been updated because a skin is required and the {@link Skeleton#getSkin() active skin}
 	 * does not contain this item.

spine-libgdx/spine-skeletonviewer/src/com/esotericsoftware/spine/SkeletonViewer.java

@@ -52,6 +52,7 @@ import com.badlogic.gdx.utils.viewport.ScreenViewport;
 import com.esotericsoftware.spine.Animation.MixBlend;
 import com.esotericsoftware.spine.AnimationState.AnimationStateAdapter;
 import com.esotericsoftware.spine.AnimationState.TrackEntry;
+import com.esotericsoftware.spine.Skeleton.Physics;
 import com.esotericsoftware.spine.utils.TwoColorPolygonBatch;
 
 import java.awt.Toolkit;
@@ -154,10 +155,7 @@ public class SkeletonViewer extends ApplicationAdapter {
 		}
 
 		skeleton = new Skeleton(skeletonData);
-		skeleton.updateWorldTransform();
-		skeleton.setToSetupPose();
-		skeleton = new Skeleton(skeleton); // Tests copy constructors.
-		skeleton.updateWorldTransform();
+		skeleton.updateWorldTransform(Physics.update);
 
 		state = new AnimationState(new AnimationStateData(skeletonData));
 		state.addListener(new AnimationStateAdapter() {
@@ -269,7 +267,7 @@ public class SkeletonViewer extends ApplicationAdapter {
 			delta = Math.min(delta, 0.032f) * ui.speedSlider.getValue();
 			state.update(delta);
 			state.apply(skeleton);
-			skeleton.updateWorldTransform();
+			skeleton.updateWorldTransform(Physics.update);
 
 			batch.begin();
 			renderer.draw(batch, skeleton);