Javadocs, argument checks, minor clean up.

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

@@ -70,7 +70,8 @@ public class Animation {
 	/** Applies all the animation's timelines to the specified skeleton.
 	 * <p>
 	 * See Timeline {@link Timeline#apply(Skeleton, float, float, Array, float, MixBlend, MixDirection)}.
-	 * @param loop If true, the animation repeats after {@link #getDuration()}. */
+	 * @param loop If true, the animation repeats after {@link #getDuration()}.
+	 * @param events May be null to ignore fired events. */
 	public void apply (Skeleton skeleton, float lastTime, float time, boolean loop, Array<Event> events, float alpha,
 		MixBlend blend, MixDirection direction) {
 		if (skeleton == null) throw new IllegalArgumentException("skeleton cannot be null.");
@@ -144,12 +145,12 @@ public class Animation {
 		 *           (exclusive) and <code>time</code> (inclusive).
 		 * @param time The time within the animation. Most timelines find the key before and the key after this time so they can
 		 *           interpolate between the keys.
-		 * @param events If any events are fired, they are added to this list. Can be null to ignore firing events or if the
-		 *           timeline does not fire events.
+		 * @param events If any events are fired, they are added to this list. Can be null to ignore fired events or if the timeline
+		 *           does not fire events.
 		 * @param alpha 0 applies the current or setup value (depending on <code>blend</code>). 1 applies the timeline value.
 		 *           Between 0 and 1 applies a value between the current or setup value and the timeline value. By adjusting
 		 *           <code>alpha</code> over time, an animation can be mixed in or out. <code>alpha</code> can also be useful to
-		 *           apply animations on top of each other (layered).
+		 *           apply animations on top of each other (layering).
 		 * @param blend Controls how mixing is applied when <code>alpha</code> < 1.
 		 * @param direction Indicates whether the timeline is mixing in or out. Used by timelines which perform instant transitions,
 		 *           such as {@link DrawOrderTimeline} or {@link AttachmentTimeline}. */
@@ -160,7 +161,8 @@ public class Animation {
 		public int getPropertyId ();
 	}
 
-	/** Controls how a timeline value is mixed with the setup pose value or current pose value.
+	/** Controls how a timeline value is mixed with the setup pose value or current pose value when a timeline's <code>alpha</code>
+	 * < 1.
 	 * <p>
 	 * See Timeline {@link Timeline#apply(Skeleton, float, float, Array, float, MixBlend, MixDirection)}. */
 	static public enum MixBlend {
@@ -181,7 +183,9 @@ public class Animation {
 		/** Transitions from the current value to the current value plus the timeline value. No change is made before the first key
 		 * (the current value is kept until the first key).
 		 * <p>
-		 * <code>add</code> is intended for animations layered on top of others, not for the first animations applied. */
+		 * <code>add</code> is intended for animations layered on top of others, not for the first animations applied. Properties
+		 * keyed by additive animations must be set manually or by another animation before applying the additive animations, else
+		 * the property values will increase continually. */
 		add
 	}
 
@@ -779,7 +783,8 @@ public class Animation {
 			this.slotIndex = index;
 		}
 
-		/** The index of the slot in {@link Skeleton#getSlots()} that will be changed. */
+		/** The index of the slot in {@link Skeleton#getSlots()} that will be changed. The {@link Slot#getDarkColor()} must not be
+		 * null. */
 		public int getSlotIndex () {
 			return slotIndex;
 		}

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

@@ -462,6 +462,7 @@ public class AnimationState {
 	 * It may be desired to use {@link AnimationState#setEmptyAnimation(int, float)} to mix the skeletons back to the setup pose,
 	 * rather than leaving them in their current pose. */
 	public void clearTrack (int trackIndex) {
+		if (trackIndex < 0) throw new IllegalArgumentException("trackIndex must be >= 0.");
 		if (trackIndex >= tracks.size) return;
 		TrackEntry current = tracks.get(trackIndex);
 		if (current == null) return;
@@ -521,6 +522,7 @@ public class AnimationState {
 	 * @return A track entry to allow further customization of animation playback. References to the track entry must not be kept
 	 *         after the {@link AnimationStateListener#dispose(TrackEntry)} event occurs. */
 	public TrackEntry setAnimation (int trackIndex, Animation animation, boolean loop) {
+		if (trackIndex < 0) throw new IllegalArgumentException("trackIndex must be >= 0.");
 		if (animation == null) throw new IllegalArgumentException("animation cannot be null.");
 		boolean interrupt = true;
 		TrackEntry current = expandToIndex(trackIndex);
@@ -560,6 +562,7 @@ public class AnimationState {
 	 * @return A track entry to allow further customization of animation playback. References to the track entry must not be kept
 	 *         after the {@link AnimationStateListener#dispose(TrackEntry)} event occurs. */
 	public TrackEntry addAnimation (int trackIndex, Animation animation, boolean loop, float delay) {
+		if (trackIndex < 0) throw new IllegalArgumentException("trackIndex must be >= 0.");
 		if (animation == null) throw new IllegalArgumentException("animation cannot be null.");
 
 		TrackEntry last = expandToIndex(trackIndex);
@@ -783,6 +786,7 @@ public class AnimationState {
 
 	/** Returns the track entry for the animation currently playing on the track, or null if no animation is currently playing. */
 	public TrackEntry getCurrent (int trackIndex) {
+		if (trackIndex < 0) throw new IllegalArgumentException("trackIndex must be >= 0.");
 		if (trackIndex >= tracks.size) return null;
 		return tracks.get(trackIndex);
 	}
@@ -892,6 +896,7 @@ public class AnimationState {
 		}
 
 		public void setAnimation (Animation animation) {
+			if (animation == null) throw new IllegalArgumentException("animation cannot be null.");
 			this.animation = animation;
 		}
 
@@ -1124,6 +1129,7 @@ public class AnimationState {
 		}
 
 		public void setMixBlend (MixBlend mixBlend) {
+			if (mixBlend == null) throw new IllegalArgumentException("mixBlend cannot be null.");
 			this.mixBlend = mixBlend;
 		}
 
@@ -1178,40 +1184,40 @@ public class AnimationState {
 		private final Array objects = new Array();
 		boolean drainDisabled;
 
-		public void start (TrackEntry entry) {
+		void start (TrackEntry entry) {
 			objects.add(EventType.start);
 			objects.add(entry);
 			animationsChanged = true;
 		}
 
-		public void interrupt (TrackEntry entry) {
+		void interrupt (TrackEntry entry) {
 			objects.add(EventType.interrupt);
 			objects.add(entry);
 		}
 
-		public void end (TrackEntry entry) {
+		void end (TrackEntry entry) {
 			objects.add(EventType.end);
 			objects.add(entry);
 			animationsChanged = true;
 		}
 
-		public void dispose (TrackEntry entry) {
+		void dispose (TrackEntry entry) {
 			objects.add(EventType.dispose);
 			objects.add(entry);
 		}
 
-		public void complete (TrackEntry entry) {
+		void complete (TrackEntry entry) {
 			objects.add(EventType.complete);
 			objects.add(entry);
 		}
 
-		public void event (TrackEntry entry, Event event) {
+		void event (TrackEntry entry, Event event) {
 			objects.add(EventType.event);
 			objects.add(entry);
 			objects.add(event);
 		}
 
-		public void drain () {
+		void drain () {
 			if (drainDisabled) return; // Not reentrant.
 			drainDisabled = true;
 
@@ -1260,7 +1266,7 @@ public class AnimationState {
 			drainDisabled = false;
 		}
 
-		public void clear () {
+		void clear () {
 			objects.clear();
 		}
 	}

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

@@ -55,5 +55,5 @@ public enum BlendMode {
 		return dest;
 	}
 
-	static public BlendMode[] values = values();
+	static public final BlendMode[] values = values();
 }

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

@@ -538,6 +538,7 @@ public class Bone implements Updatable {
 
 	/** Transforms a point from world coordinates to the bone's local coordinates. */
 	public Vector2 worldToLocal (Vector2 world) {
+		if (world == null) throw new IllegalArgumentException("world cannot be null.");
 		float invDet = 1 / (a * d - b * c);
 		float x = world.x - worldX, y = world.y - worldY;
 		world.x = x * d * invDet - y * b * invDet;
@@ -547,6 +548,7 @@ public class Bone implements Updatable {
 
 	/** Transforms a point from the bone's local coordinates to world coordinates. */
 	public Vector2 localToWorld (Vector2 local) {
+		if (local == null) throw new IllegalArgumentException("local cannot be null.");
 		float x = local.x, y = local.y;
 		local.x = x * a + y * b + worldX;
 		local.y = x * c + y * d + worldY;

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

@@ -173,6 +173,7 @@ public class BoneData {
 	}
 
 	public void setTransformMode (TransformMode transformMode) {
+		if (transformMode == null) throw new IllegalArgumentException("transformMode cannot be null.");
 		this.transformMode = transformMode;
 	}
 

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

@@ -73,6 +73,7 @@ public class Event {
 	}
 
 	public void setString (String stringValue) {
+		if (stringValue == null) throw new IllegalArgumentException("stringValue cannot be null.");
 		this.stringValue = stringValue;
 	}
 

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

@@ -65,6 +65,7 @@ public class EventData {
 	}
 
 	public void setString (String stringValue) {
+		if (stringValue == null) throw new IllegalArgumentException("stringValue cannot be null.");
 		this.stringValue = stringValue;
 	}
 
@@ -73,6 +74,7 @@ public class EventData {
 	}
 
 	public void setAudioPath (String audioPath) {
+		if (audioPath == null) throw new IllegalArgumentException("audioPath cannot be null.");
 		this.audioPath = audioPath;
 	}
 

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

@@ -106,6 +106,7 @@ public class IkConstraint implements Updatable {
 	}
 
 	public void setTarget (Bone target) {
+		if (target == null) throw new IllegalArgumentException("target cannot be null.");
 		this.target = target;
 	}
 
@@ -162,6 +163,7 @@ public class IkConstraint implements Updatable {
 	/** 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 id = 1 / (p.a * p.d - p.b * p.c);
@@ -188,6 +190,8 @@ public class IkConstraint implements Updatable {
 	/** 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 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;

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

@@ -497,6 +497,7 @@ public class PathConstraint implements Updatable {
 	}
 
 	public void setTarget (Slot target) {
+		if (target == null) throw new IllegalArgumentException("target cannot be null.");
 		this.target = target;
 	}
 

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

@@ -58,6 +58,7 @@ public class PathConstraintData extends ConstraintData {
 	}
 
 	public void setTarget (SlotData target) {
+		if (target == null) throw new IllegalArgumentException("target cannot be null.");
 		this.target = target;
 	}
 
@@ -67,6 +68,7 @@ public class PathConstraintData extends ConstraintData {
 	}
 
 	public void setPositionMode (PositionMode positionMode) {
+		if (positionMode == null) throw new IllegalArgumentException("positionMode cannot be null.");
 		this.positionMode = positionMode;
 	}
 
@@ -76,6 +78,7 @@ public class PathConstraintData extends ConstraintData {
 	}
 
 	public void setSpacingMode (SpacingMode spacingMode) {
+		if (spacingMode == null) throw new IllegalArgumentException("spacingMode cannot be null.");
 		this.spacingMode = spacingMode;
 	}
 
@@ -85,6 +88,7 @@ public class PathConstraintData extends ConstraintData {
 	}
 
 	public void setRotateMode (RotateMode rotateMode) {
+		if (rotateMode == null) throw new IllegalArgumentException("rotateMode cannot be null.");
 		this.rotateMode = rotateMode;
 	}
 

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

@@ -362,6 +362,7 @@ public class Skeleton {
 	 * See <a href="http://esotericsoftware.com/spine-runtime-skeletons#World-transforms">World transforms</a> in the Spine
 	 * Runtimes Guide. */
 	public void updateWorldTransform (Bone parent) {
+		if (parent == null) throw new IllegalArgumentException("parent cannot be null.");
 		// This partial update avoids computing the world transform for constrained bones when 1) the bone is not updated
 		// before the constraint, 2) the constraint only needs to access the applied local transform, and 3) the constraint calls
 		// updateWorldTransform.
@@ -462,6 +463,7 @@ public class Skeleton {
 		return bones;
 	}
 
+	/** The list of bones and constraints, sorted in the order they should be updated, as computed by {@link #updateCache()}. */
 	public Array<Updatable> getUpdateCache () {
 		return updateCache;
 	}
@@ -473,7 +475,7 @@ public class Skeleton {
 	}
 
 	/** Finds a bone by comparing each bone's name. It is more efficient to cache the results of this method than to call it
-	 * multiple times.
+	 * repeatedly.
 	 * @return May be null. */
 	public Bone findBone (String boneName) {
 		if (boneName == null) throw new IllegalArgumentException("boneName cannot be null.");
@@ -491,7 +493,7 @@ public class Skeleton {
 	}
 
 	/** Finds a slot by comparing each slot's name. It is more efficient to cache the results of this method than to call it
-	 * multiple times.
+	 * repeatedly.
 	 * @return May be null. */
 	public Slot findSlot (String slotName) {
 		if (slotName == null) throw new IllegalArgumentException("slotName cannot be null.");
@@ -607,7 +609,7 @@ public class Skeleton {
 	}
 
 	/** Finds an IK constraint by comparing each IK constraint's name. It is more efficient to cache the results of this method
-	 * than to call it multiple times.
+	 * than to call it repeatedly.
 	 * @return May be null. */
 	public IkConstraint findIkConstraint (String constraintName) {
 		if (constraintName == null) throw new IllegalArgumentException("constraintName cannot be null.");
@@ -625,7 +627,7 @@ public class Skeleton {
 	}
 
 	/** Finds a transform constraint by comparing each transform constraint's name. It is more efficient to cache the results of
-	 * this method than to call it multiple times.
+	 * this method than to call it repeatedly.
 	 * @return May be null. */
 	public TransformConstraint findTransformConstraint (String constraintName) {
 		if (constraintName == null) throw new IllegalArgumentException("constraintName cannot be null.");
@@ -643,7 +645,7 @@ public class Skeleton {
 	}
 
 	/** Finds a path constraint by comparing each path constraint's name. It is more efficient to cache the results of this method
-	 * than to call it multiple times.
+	 * than to call it repeatedly.
 	 * @return May be null. */
 	public PathConstraint findPathConstraint (String constraintName) {
 		if (constraintName == null) throw new IllegalArgumentException("constraintName cannot be null.");
@@ -658,10 +660,11 @@ public class Skeleton {
 	/** Returns the axis aligned bounding box (AABB) of the region and mesh attachments for the current pose.
 	 * @param offset An output value, the distance from the skeleton origin to the bottom left corner of the AABB.
 	 * @param size An output value, the width and height of the AABB.
-	 * @param temp Working memory. */
+	 * @param temp Working memory to temporarily store attachments' computed world vertices. */
 	public void getBounds (Vector2 offset, Vector2 size, FloatArray temp) {
 		if (offset == null) throw new IllegalArgumentException("offset cannot be null.");
 		if (size == null) throw new IllegalArgumentException("size cannot be null.");
+		if (temp == null) throw new IllegalArgumentException("temp cannot be null.");
 		Array<Slot> drawOrder = this.drawOrder;
 		float minX = Integer.MAX_VALUE, minY = Integer.MAX_VALUE, maxX = Integer.MIN_VALUE, maxY = Integer.MIN_VALUE;
 		for (int i = 0, n = drawOrder.size; i < n; i++) {
@@ -748,6 +751,7 @@ public class Skeleton {
 		this.y = y;
 	}
 
+	/** Sets the skeleton X and Y position, which is added to the root bone worldX and worldY position. */
 	public void setPosition (float x, float y) {
 		this.x = x;
 		this.y = y;

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

@@ -122,6 +122,7 @@ public class SkeletonBinary {
 	}
 
 	public void setScale (float scale) {
+		if (scale == 0) throw new IllegalArgumentException("scale cannot be 0.");
 		this.scale = scale;
 	}
 

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

@@ -35,8 +35,8 @@ import com.badlogic.gdx.utils.Pool;
 import com.esotericsoftware.spine.attachments.Attachment;
 import com.esotericsoftware.spine.attachments.BoundingBoxAttachment;
 
-/** Collects each {@link BoundingBoxAttachment} that is visible and computes the world vertices for its polygon. The polygon
- * vertices are provided along with convenience methods for doing hit detection. */
+/** Collects each visible {@link BoundingBoxAttachment} and computes the world vertices for its polygon. The polygon vertices are
+ * provided along with convenience methods for doing hit detection. */
 public class SkeletonBounds {
 	private float minX, minY, maxX, maxY;
 	private Array<BoundingBoxAttachment> boundingBoxes = new Array();
@@ -135,6 +135,7 @@ public class SkeletonBounds {
 
 	/** Returns true if the axis aligned bounding box intersects the axis aligned bounding box of the specified bounds. */
 	public boolean aabbIntersectsSkeleton (SkeletonBounds bounds) {
+		if (bounds == null) throw new IllegalArgumentException("bounds cannot be null.");
 		return minX < bounds.maxX && maxX > bounds.minX && minY < bounds.maxY && maxY > bounds.minY;
 	}
 
@@ -149,6 +150,7 @@ public class SkeletonBounds {
 
 	/** Returns true if the polygon contains the point. */
 	public boolean containsPoint (FloatArray polygon, float x, float y) {
+		if (polygon == null) throw new IllegalArgumentException("polygon cannot be null.");
 		float[] vertices = polygon.items;
 		int nn = polygon.size;
 
@@ -178,6 +180,7 @@ public class SkeletonBounds {
 
 	/** Returns true if the polygon contains any part of the line segment. */
 	public boolean intersectsSegment (FloatArray polygon, float x1, float y1, float x2, float y2) {
+		if (polygon == null) throw new IllegalArgumentException("polygon cannot be null.");
 		float[] vertices = polygon.items;
 		int nn = polygon.size;
 

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

@@ -99,10 +99,12 @@ public class SkeletonJson {
 	}
 
 	public void setScale (float scale) {
+		if (scale == 0) throw new IllegalArgumentException("scale cannot be 0.");
 		this.scale = scale;
 	}
 
 	protected JsonValue parse (FileHandle file) {
+		if (file == null) throw new IllegalArgumentException("file cannot be null.");
 		return new JsonReader().parse(file);
 	}
 

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

@@ -29,14 +29,6 @@
 
 package com.esotericsoftware.spine;
 
-import com.esotericsoftware.spine.attachments.Attachment;
-import com.esotericsoftware.spine.attachments.ClippingAttachment;
-import com.esotericsoftware.spine.attachments.MeshAttachment;
-import com.esotericsoftware.spine.attachments.RegionAttachment;
-import com.esotericsoftware.spine.attachments.SkeletonAttachment;
-import com.esotericsoftware.spine.utils.SkeletonClipping;
-import com.esotericsoftware.spine.utils.TwoColorPolygonBatch;
-
 import com.badlogic.gdx.graphics.Color;
 import com.badlogic.gdx.graphics.Texture;
 import com.badlogic.gdx.graphics.g2d.Batch;
@@ -47,6 +39,14 @@ import com.badlogic.gdx.utils.FloatArray;
 import com.badlogic.gdx.utils.NumberUtils;
 import com.badlogic.gdx.utils.ShortArray;
 
+import com.esotericsoftware.spine.attachments.Attachment;
+import com.esotericsoftware.spine.attachments.ClippingAttachment;
+import com.esotericsoftware.spine.attachments.MeshAttachment;
+import com.esotericsoftware.spine.attachments.RegionAttachment;
+import com.esotericsoftware.spine.attachments.SkeletonAttachment;
+import com.esotericsoftware.spine.utils.SkeletonClipping;
+import com.esotericsoftware.spine.utils.TwoColorPolygonBatch;
+
 public class SkeletonRenderer {
 	static private final short[] quadTriangles = {0, 1, 2, 2, 3, 0};
 
@@ -72,10 +72,13 @@ public class SkeletonRenderer {
 		if (batch instanceof TwoColorPolygonBatch) {
 			draw((TwoColorPolygonBatch)batch, skeleton);
 			return;
-		} else if (batch instanceof PolygonSpriteBatch) {
+		}
+		if (batch instanceof PolygonSpriteBatch) {
 			draw((PolygonSpriteBatch)batch, skeleton);
 			return;
 		}
+		if (batch == null) throw new IllegalArgumentException("batch cannot be null.");
+		if (skeleton == null) throw new IllegalArgumentException("skeleton cannot be null.");
 
 		VertexEffect vertexEffect = this.vertexEffect;
 		if (vertexEffect != null) vertexEffect.begin(skeleton);
@@ -148,12 +151,12 @@ public class SkeletonRenderer {
 	 * next. */
 	@SuppressWarnings("null")
 	public void draw (PolygonSpriteBatch batch, Skeleton skeleton) {
-		Vector2 tempPos = this.temp;
-		Vector2 tempUv = this.temp2;
-		Color tempLight = this.temp3;
-		Color tempDark = this.temp4;
-		Color temp5 = this.temp5;
-		Color temp6 = this.temp6;
+		if (batch == null) throw new IllegalArgumentException("batch cannot be null.");
+		if (skeleton == null) throw new IllegalArgumentException("skeleton cannot be null.");
+
+		Vector2 tempPosition = this.temp, tempUV = this.temp2;
+		Color tempLight1 = this.temp3, tempDark1 = this.temp4;
+		Color tempLight2 = this.temp5, tempDark2 = this.temp6;
 		VertexEffect vertexEffect = this.vertexEffect;
 		if (vertexEffect != null) vertexEffect.begin(skeleton);
 
@@ -231,21 +234,21 @@ public class SkeletonRenderer {
 						clippedTriangles.size);
 				} else {
 					if (vertexEffect != null) {
-						temp5.set(NumberUtils.floatToIntColor(c));
-						temp6.set(0);
+						tempLight1.set(NumberUtils.floatToIntColor(c));
+						tempDark1.set(0);
 						for (int v = 0, u = 0; v < verticesLength; v += 5, u += 2) {
-							tempPos.x = vertices[v];
-							tempPos.y = vertices[v + 1];
-							tempLight.set(temp5);
-							tempDark.set(temp6);
-							tempUv.x = uvs[u];
-							tempUv.y = uvs[u + 1];
-							vertexEffect.transform(tempPos, tempUv, tempLight, tempDark);
-							vertices[v] = tempPos.x;
-							vertices[v + 1] = tempPos.y;
-							vertices[v + 2] = tempLight.toFloatBits();
-							vertices[v + 3] = tempUv.x;
-							vertices[v + 4] = tempUv.y;
+							tempPosition.x = vertices[v];
+							tempPosition.y = vertices[v + 1];
+							tempLight2.set(tempLight1);
+							tempDark2.set(tempDark1);
+							tempUV.x = uvs[u];
+							tempUV.y = uvs[u + 1];
+							vertexEffect.transform(tempPosition, tempUV, tempLight2, tempDark2);
+							vertices[v] = tempPosition.x;
+							vertices[v + 1] = tempPosition.y;
+							vertices[v + 2] = tempLight2.toFloatBits();
+							vertices[v + 3] = tempUV.x;
+							vertices[v + 4] = tempUV.y;
 						}
 					} else {
 						for (int v = 2, u = 0; v < verticesLength; v += 5, u += 2) {
@@ -271,12 +274,12 @@ public class SkeletonRenderer {
 	 * next. */
 	@SuppressWarnings("null")
 	public void draw (TwoColorPolygonBatch batch, Skeleton skeleton) {
-		Vector2 tempPos = this.temp;
-		Vector2 tempUv = this.temp2;
-		Color tempLight = this.temp3;
-		Color tempDark = this.temp4;
-		Color temp5 = this.temp5;
-		Color temp6 = this.temp6;
+		if (batch == null) throw new IllegalArgumentException("batch cannot be null.");
+		if (skeleton == null) throw new IllegalArgumentException("skeleton cannot be null.");
+
+		Vector2 tempPosition = this.temp, tempUV = this.temp2;
+		Color tempLight1 = this.temp3, tempDark1 = this.temp4;
+		Color tempLight2 = this.temp5, tempDark2 = this.temp6;
 		VertexEffect vertexEffect = this.vertexEffect;
 		if (vertexEffect != null) vertexEffect.begin(skeleton);
 
@@ -363,22 +366,22 @@ public class SkeletonRenderer {
 						clippedTriangles.size);
 				} else {
 					if (vertexEffect != null) {
-						temp5.set(NumberUtils.floatToIntColor(light));
-						temp6.set(NumberUtils.floatToIntColor(dark));
+						tempLight1.set(NumberUtils.floatToIntColor(light));
+						tempDark1.set(NumberUtils.floatToIntColor(dark));
 						for (int v = 0, u = 0; v < verticesLength; v += 6, u += 2) {
-							tempPos.x = vertices[v];
-							tempPos.y = vertices[v + 1];
-							tempLight.set(temp5);
-							tempDark.set(temp6);
-							tempUv.x = uvs[u];
-							tempUv.y = uvs[u + 1];
-							vertexEffect.transform(tempPos, tempUv, tempLight, tempDark);
-							vertices[v] = tempPos.x;
-							vertices[v + 1] = tempPos.y;
-							vertices[v + 2] = tempLight.toFloatBits();
-							vertices[v + 3] = tempDark.toFloatBits();
-							vertices[v + 4] = tempUv.x;
-							vertices[v + 5] = tempUv.y;
+							tempPosition.x = vertices[v];
+							tempPosition.y = vertices[v + 1];
+							tempLight2.set(tempLight1);
+							tempDark2.set(tempDark1);
+							tempUV.x = uvs[u];
+							tempUV.y = uvs[u + 1];
+							vertexEffect.transform(tempPosition, tempUV, tempLight2, tempDark2);
+							vertices[v] = tempPosition.x;
+							vertices[v + 1] = tempPosition.y;
+							vertices[v + 2] = tempLight2.toFloatBits();
+							vertices[v + 3] = tempDark2.toFloatBits();
+							vertices[v + 4] = tempUV.x;
+							vertices[v + 5] = tempUV.y;
 						}
 					} else {
 						for (int v = 2, u = 0; v < verticesLength; v += 6, u += 2) {
@@ -399,45 +402,42 @@ public class SkeletonRenderer {
 	}
 
 	private void applyVertexEffect (float[] vertices, int verticesLength, int stride, float light, float dark) {
-		Vector2 tempPos = this.temp;
-		Vector2 tempUv = this.temp2;
-		Color tempLight = this.temp3;
-		Color tempDark = this.temp4;
-		Color temp5 = this.temp5;
-		Color temp6 = this.temp6;
+		Vector2 tempPosition = this.temp, tempUV = this.temp2;
+		Color tempLight1 = this.temp3, tempDark1 = this.temp4;
+		Color tempLight2 = this.temp5, tempDark2 = this.temp6;
 		VertexEffect vertexEffect = this.vertexEffect;
-		temp5.set(NumberUtils.floatToIntColor(light));
-		temp6.set(NumberUtils.floatToIntColor(dark));
+		tempLight1.set(NumberUtils.floatToIntColor(light));
+		tempDark1.set(NumberUtils.floatToIntColor(dark));
 		if (stride == 5) {
 			for (int v = 0; v < verticesLength; v += stride) {
-				tempPos.x = vertices[v];
-				tempPos.y = vertices[v + 1];
-				tempUv.x = vertices[v + 3];
-				tempUv.y = vertices[v + 4];
-				tempLight.set(temp5);
-				tempDark.set(temp6);
-				vertexEffect.transform(tempPos, tempUv, tempLight, tempDark);
-				vertices[v] = tempPos.x;
-				vertices[v + 1] = tempPos.y;
-				vertices[v + 2] = tempLight.toFloatBits();
-				vertices[v + 3] = tempUv.x;
-				vertices[v + 4] = tempUv.y;
+				tempPosition.x = vertices[v];
+				tempPosition.y = vertices[v + 1];
+				tempUV.x = vertices[v + 3];
+				tempUV.y = vertices[v + 4];
+				tempLight2.set(tempLight1);
+				tempDark2.set(tempDark1);
+				vertexEffect.transform(tempPosition, tempUV, tempLight2, tempDark2);
+				vertices[v] = tempPosition.x;
+				vertices[v + 1] = tempPosition.y;
+				vertices[v + 2] = tempLight2.toFloatBits();
+				vertices[v + 3] = tempUV.x;
+				vertices[v + 4] = tempUV.y;
 			}
 		} else {
 			for (int v = 0; v < verticesLength; v += stride) {
-				tempPos.x = vertices[v];
-				tempPos.y = vertices[v + 1];
-				tempUv.x = vertices[v + 4];
-				tempUv.y = vertices[v + 5];
-				tempLight.set(temp5);
-				tempDark.set(temp6);
-				vertexEffect.transform(tempPos, tempUv, tempLight, tempDark);
-				vertices[v] = tempPos.x;
-				vertices[v + 1] = tempPos.y;
-				vertices[v + 2] = tempLight.toFloatBits();
-				vertices[v + 3] = tempDark.toFloatBits();
-				vertices[v + 4] = tempUv.x;
-				vertices[v + 5] = tempUv.y;
+				tempPosition.x = vertices[v];
+				tempPosition.y = vertices[v + 1];
+				tempUV.x = vertices[v + 4];
+				tempUV.y = vertices[v + 5];
+				tempLight2.set(tempLight1);
+				tempDark2.set(tempDark1);
+				vertexEffect.transform(tempPosition, tempUV, tempLight2, tempDark2);
+				vertices[v] = tempPosition.x;
+				vertices[v + 1] = tempPosition.y;
+				vertices[v + 2] = tempLight2.toFloatBits();
+				vertices[v + 3] = tempDark2.toFloatBits();
+				vertices[v + 4] = tempUV.x;
+				vertices[v + 5] = tempUV.y;
 			}
 		}
 	}
@@ -450,14 +450,17 @@ public class SkeletonRenderer {
 		this.premultipliedAlpha = premultipliedAlpha;
 	}
 
+	/** @return May be null. */
 	public VertexEffect getVertexEffect () {
 		return vertexEffect;
 	}
 
+	/** @param vertexEffect May be null. */
 	public void setVertexEffect (VertexEffect vertexEffect) {
 		this.vertexEffect = vertexEffect;
 	}
 
+	/** Modifies the skeleton or vertex positions, UVs, or colors during rendering. */
 	static public interface VertexEffect {
 		public void begin (Skeleton skeleton);
 

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

@@ -67,10 +67,13 @@ public class SkeletonRendererDebug {
 	}
 
 	public SkeletonRendererDebug (ShapeRenderer shapes) {
+		if (shapes == null) throw new IllegalArgumentException("shapes cannot be null.");
 		this.shapes = shapes;
 	}
 
 	public void draw (Skeleton skeleton) {
+		if (skeleton == null) throw new IllegalArgumentException("skeleton cannot be null.");
+
 		Gdx.gl.glEnable(GL20.GL_BLEND);
 		int srcFunc = premultipliedAlpha ? GL20.GL_ONE : GL20.GL_SRC_ALPHA;
 		Gdx.gl.glBlendFunc(srcFunc, GL20.GL_ONE_MINUS_SRC_ALPHA);

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

@@ -31,6 +31,7 @@ package com.esotericsoftware.spine;
 
 import com.badlogic.gdx.utils.Array;
 import com.badlogic.gdx.utils.OrderedMap;
+
 import com.esotericsoftware.spine.attachments.Attachment;
 import com.esotericsoftware.spine.attachments.MeshAttachment;
 
@@ -53,13 +54,15 @@ public class Skin {
 
 	/** Adds an attachment to the skin for the specified slot index and name. */
 	public void setAttachment (int slotIndex, String name, Attachment attachment) {
-		if (attachment == null) throw new IllegalArgumentException("attachment cannot be null.");
 		if (slotIndex < 0) throw new IllegalArgumentException("slotIndex must be >= 0.");
+		if (attachment == null) throw new IllegalArgumentException("attachment cannot be null.");
 		attachments.put(new SkinEntry(slotIndex, name, attachment), attachment);
 	}
 
 	/** Adds all attachments, bones, and constraints from the specified skin to this skin. */
 	public void addSkin (Skin skin) {
+		if (skin == null) throw new IllegalArgumentException("skin cannot be null.");
+
 		for (BoneData data : skin.bones)
 			if (!bones.contains(data, true)) bones.add(data);
 
@@ -70,8 +73,11 @@ public class Skin {
 			setAttachment(entry.slotIndex, entry.name, entry.attachment);
 	}
 
-	/** Adds all attachments, bones, and constraints from the specified skin to this skin. Attachments are deep copied. */
+	/** Adds all bones and constraints and copies of all attachments from the specified skin to this skin. Mesh attachments are not
+	 * copied, instead a new linked mesh is created. The attachment copies can be modified without affecting the originals. */
 	public void copySkin (Skin skin) {
+		if (skin == null) throw new IllegalArgumentException("skin cannot be null.");
+
 		for (BoneData data : skin.bones)
 			if (!bones.contains(data, true)) bones.add(data);
 
@@ -80,8 +86,7 @@ public class Skin {
 
 		for (SkinEntry entry : skin.attachments.keys()) {
 			if (entry.attachment instanceof MeshAttachment)
-				setAttachment(entry.slotIndex, entry.name,
-					entry.attachment != null ? ((MeshAttachment)entry.attachment).newLinkedMesh() : null);
+				setAttachment(entry.slotIndex, entry.name, ((MeshAttachment)entry.attachment).newLinkedMesh());
 			else
 				setAttachment(entry.slotIndex, entry.name, entry.attachment != null ? entry.attachment.copy() : null);
 		}
@@ -108,6 +113,8 @@ public class Skin {
 
 	/** Returns all attachments in this skin for the specified slot index. */
 	public void getAttachments (int slotIndex, Array<SkinEntry> attachments) {
+		if (slotIndex < 0) throw new IllegalArgumentException("slotIndex must be >= 0.");
+		if (attachments == null) throw new IllegalArgumentException("attachments cannot be null.");
 		for (SkinEntry entry : this.attachments.keys())
 			if (entry.slotIndex == slotIndex) attachments.add(entry);
 	}

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

@@ -77,6 +77,7 @@ public class SlotData {
 		return darkColor;
 	}
 
+	/** @param darkColor May be null. */
 	public void setDarkColor (Color darkColor) {
 		this.darkColor = darkColor;
 	}
@@ -97,6 +98,7 @@ public class SlotData {
 	}
 
 	public void setBlendMode (BlendMode blendMode) {
+		if (blendMode == null) throw new IllegalArgumentException("blendMode cannot be null.");
 		this.blendMode = blendMode;
 	}
 

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

@@ -301,6 +301,7 @@ public class TransformConstraint implements Updatable {
 	}
 
 	public void setTarget (Bone target) {
+		if (target == null) throw new IllegalArgumentException("target cannot be null.");
 		this.target = target;
 	}
 

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

@@ -33,8 +33,8 @@ package com.esotericsoftware.spine;
 public interface Updatable {
 	public void update ();
 
-	/** Returns false when this item has not been updated because a skine is required and the {@link Skeleton#getSkin() active
-	 * skin} does not contain this item.
+	/** 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.
 	 * @see Skin#getBones()
 	 * @see Skin#getConstraints() */
 	public boolean isActive ();

spine-libgdx/spine-libgdx/src/com/esotericsoftware/spine/attachments/AttachmentType.java

@@ -32,5 +32,5 @@ package com.esotericsoftware.spine.attachments;
 public enum AttachmentType {
 	region, boundingbox, mesh, linkedmesh, path, point, clipping;
 
-	static public AttachmentType[] values = values();
+	static public final AttachmentType[] values = values();
 }

spine-libgdx/spine-libgdx/src/com/esotericsoftware/spine/attachments/MeshAttachment.java

@@ -259,7 +259,7 @@ public class MeshAttachment extends VertexAttachment {
 		return copy;
 	}
 
-	/** Returns a new mesh with this mesh set as the {@link #parentMesh}. **/
+	/** Returns a new mesh with the {@link #parentMesh} set to this mesh's parent mesh, if any, else to this mesh. **/
 	public MeshAttachment newLinkedMesh () {
 		MeshAttachment mesh = new MeshAttachment(name);
 		mesh.region = region;