float[] ComputeWorldPositions(PathAttachment path, int spacesCount, bool tangents, bool percentPosition,
                                      bool percentSpacing)
        {
            Slot  target   = this.target;
            float position = this.position;

            float[] spacesItems = this.spaces.Items, output = this.positions.Resize(spacesCount * 3 + 2).Items, world;
            bool    closed = path.Closed;
            int     verticesLength = path.WorldVerticesLength, curveCount = verticesLength / 6, prevCurve = NONE;

            float pathLength;

            if (!path.ConstantSpeed)
            {
                float[] lengths = path.Lengths;
                curveCount -= closed ? 1 : 2;
                pathLength  = lengths[curveCount];
                if (percentPosition)
                {
                    position *= pathLength;
                }
                if (percentSpacing)
                {
                    for (int i = 0; i < spacesCount; i++)
                    {
                        spacesItems[i] *= pathLength;
                    }
                }
                world = this.world.Resize(8).Items;
                for (int i = 0, o = 0, curve = 0; i < spacesCount; i++, o += 3)
                {
                    float space = spacesItems[i];
                    position += space;
                    float p = position;

                    if (closed)
                    {
                        p %= pathLength;
                        if (p < 0)
                        {
                            p += pathLength;
                        }
                        curve = 0;
                    }
                    else if (p < 0)
                    {
                        if (prevCurve != BEFORE)
                        {
                            prevCurve = BEFORE;
                            path.ComputeWorldVertices(target, 2, 4, world, 0);
                        }
                        AddBeforePosition(p, world, 0, output, o);
                        continue;
                    }
                    else if (p > pathLength)
                    {
                        if (prevCurve != AFTER)
                        {
                            prevCurve = AFTER;
                            path.ComputeWorldVertices(target, verticesLength - 6, 4, world, 0);
                        }
                        AddAfterPosition(p - pathLength, world, 0, output, o);
                        continue;
                    }

                    // Determine curve containing position.
                    for (;; curve++)
                    {
                        float length = lengths[curve];
                        if (p > length)
                        {
                            continue;
                        }
                        if (curve == 0)
                        {
                            p /= length;
                        }
                        else
                        {
                            float prev = lengths[curve - 1];
                            p = (p - prev) / (length - prev);
                        }
                        break;
                    }
                    if (curve != prevCurve)
                    {
                        prevCurve = curve;
                        if (closed && curve == curveCount)
                        {
                            path.ComputeWorldVertices(target, verticesLength - 4, 4, world, 0);
                            path.ComputeWorldVertices(target, 0, 4, world, 4);
                        }
                        else
                        {
                            path.ComputeWorldVertices(target, curve * 6 + 2, 8, world, 0);
                        }
                    }
                    AddCurvePosition(p, world[0], world[1], world[2], world[3], world[4], world[5], world[6], world[7], output, o,
                                     tangents || (i > 0 && space < PathConstraint.Epsilon));
                }
                return(output);
            }

            // World vertices.
            if (closed)
            {
                verticesLength += 2;
                world           = this.world.Resize(verticesLength).Items;
                path.ComputeWorldVertices(target, 2, verticesLength - 4, world, 0);
                path.ComputeWorldVertices(target, 0, 2, world, verticesLength - 4);
                world[verticesLength - 2] = world[0];
                world[verticesLength - 1] = world[1];
            }
            else
            {
                curveCount--;
                verticesLength -= 4;
                world           = this.world.Resize(verticesLength).Items;
                path.ComputeWorldVertices(target, 2, verticesLength, world, 0);
            }

            // Curve lengths.
            float[] curves = this.curves.Resize(curveCount).Items;
            pathLength = 0;
            float x1 = world[0], y1 = world[1], cx1 = 0, cy1 = 0, cx2 = 0, cy2 = 0, x2 = 0, y2 = 0;
            float tmpx, tmpy, dddfx, dddfy, ddfx, ddfy, dfx, dfy;

            for (int i = 0, w = 2; i < curveCount; i++, w += 6)
            {
                cx1         = world[w];
                cy1         = world[w + 1];
                cx2         = world[w + 2];
                cy2         = world[w + 3];
                x2          = world[w + 4];
                y2          = world[w + 5];
                tmpx        = (x1 - cx1 * 2 + cx2) * 0.1875f;
                tmpy        = (y1 - cy1 * 2 + cy2) * 0.1875f;
                dddfx       = ((cx1 - cx2) * 3 - x1 + x2) * 0.09375f;
                dddfy       = ((cy1 - cy2) * 3 - y1 + y2) * 0.09375f;
                ddfx        = tmpx * 2 + dddfx;
                ddfy        = tmpy * 2 + dddfy;
                dfx         = (cx1 - x1) * 0.75f + tmpx + dddfx * 0.16666667f;
                dfy         = (cy1 - y1) * 0.75f + tmpy + dddfy * 0.16666667f;
                pathLength += (float)Math.Sqrt(dfx * dfx + dfy * dfy);
                dfx        += ddfx;
                dfy        += ddfy;
                ddfx       += dddfx;
                ddfy       += dddfy;
                pathLength += (float)Math.Sqrt(dfx * dfx + dfy * dfy);
                dfx        += ddfx;
                dfy        += ddfy;
                pathLength += (float)Math.Sqrt(dfx * dfx + dfy * dfy);
                dfx        += ddfx + dddfx;
                dfy        += ddfy + dddfy;
                pathLength += (float)Math.Sqrt(dfx * dfx + dfy * dfy);
                curves[i]   = pathLength;
                x1          = x2;
                y1          = y2;
            }
            if (percentPosition)
            {
                position *= pathLength;
            }
            if (percentSpacing)
            {
                for (int i = 0; i < spacesCount; i++)
                {
                    spacesItems[i] *= pathLength;
                }
            }

            float[] segments    = this.segments;
            float   curveLength = 0;

            for (int i = 0, o = 0, curve = 0, segment = 0; i < spacesCount; i++, o += 3)
            {
                float space = spacesItems[i];
                position += space;
                float p = position;

                if (closed)
                {
                    p %= pathLength;
                    if (p < 0)
                    {
                        p += pathLength;
                    }
                    curve = 0;
                }
                else if (p < 0)
                {
                    AddBeforePosition(p, world, 0, output, o);
                    continue;
                }
                else if (p > pathLength)
                {
                    AddAfterPosition(p - pathLength, world, verticesLength - 4, output, o);
                    continue;
                }

                // Determine curve containing position.
                for (;; curve++)
                {
                    float length = curves[curve];
                    if (p > length)
                    {
                        continue;
                    }
                    if (curve == 0)
                    {
                        p /= length;
                    }
                    else
                    {
                        float prev = curves[curve - 1];
                        p = (p - prev) / (length - prev);
                    }
                    break;
                }

                // Curve segment lengths.
                if (curve != prevCurve)
                {
                    prevCurve = curve;
                    int ii = curve * 6;
                    x1          = world[ii];
                    y1          = world[ii + 1];
                    cx1         = world[ii + 2];
                    cy1         = world[ii + 3];
                    cx2         = world[ii + 4];
                    cy2         = world[ii + 5];
                    x2          = world[ii + 6];
                    y2          = world[ii + 7];
                    tmpx        = (x1 - cx1 * 2 + cx2) * 0.03f;
                    tmpy        = (y1 - cy1 * 2 + cy2) * 0.03f;
                    dddfx       = ((cx1 - cx2) * 3 - x1 + x2) * 0.006f;
                    dddfy       = ((cy1 - cy2) * 3 - y1 + y2) * 0.006f;
                    ddfx        = tmpx * 2 + dddfx;
                    ddfy        = tmpy * 2 + dddfy;
                    dfx         = (cx1 - x1) * 0.3f + tmpx + dddfx * 0.16666667f;
                    dfy         = (cy1 - y1) * 0.3f + tmpy + dddfy * 0.16666667f;
                    curveLength = (float)Math.Sqrt(dfx * dfx + dfy * dfy);
                    segments[0] = curveLength;
                    for (ii = 1; ii < 8; ii++)
                    {
                        dfx         += ddfx;
                        dfy         += ddfy;
                        ddfx        += dddfx;
                        ddfy        += dddfy;
                        curveLength += (float)Math.Sqrt(dfx * dfx + dfy * dfy);
                        segments[ii] = curveLength;
                    }
                    dfx         += ddfx;
                    dfy         += ddfy;
                    curveLength += (float)Math.Sqrt(dfx * dfx + dfy * dfy);
                    segments[8]  = curveLength;
                    dfx         += ddfx + dddfx;
                    dfy         += ddfy + dddfy;
                    curveLength += (float)Math.Sqrt(dfx * dfx + dfy * dfy);
                    segments[9]  = curveLength;
                    segment      = 0;
                }

                // Weight by segment length.
                p *= curveLength;
                for (;; segment++)
                {
                    float length = segments[segment];
                    if (p > length)
                    {
                        continue;
                    }
                    if (segment == 0)
                    {
                        p /= length;
                    }
                    else
                    {
                        float prev = segments[segment - 1];
                        p = segment + (p - prev) / (length - prev);
                    }
                    break;
                }
                AddCurvePosition(p * 0.1f, x1, y1, cx1, cy1, cx2, cy2, x2, y2, output, o, tangents || (i > 0 && space < PathConstraint.Epsilon));
            }
            return(output);
        }
        private Attachment ReadAttachment(Stream input, SkeletonData skeletonData, Skin skin, int slotIndex, String attachmentName, bool nonessential)
        {
            float scale = Scale;

            String name = ReadString(input);

            if (name == null)
            {
                name = attachmentName;
            }

            AttachmentType type = (AttachmentType)input.ReadByte();

            switch (type)
            {
            case AttachmentType.Region: {
                String path     = ReadString(input);
                float  rotation = ReadFloat(input);
                float  x        = ReadFloat(input);
                float  y        = ReadFloat(input);
                float  scaleX   = ReadFloat(input);
                float  scaleY   = ReadFloat(input);
                float  width    = ReadFloat(input);
                float  height   = ReadFloat(input);
                int    color    = ReadInt(input);

                if (path == null)
                {
                    path = name;
                }
                RegionAttachment region = attachmentLoader.NewRegionAttachment(skin, name, path);
                if (region == null)
                {
                    return(null);
                }
                region.Path     = path;
                region.x        = x * scale;
                region.y        = y * scale;
                region.scaleX   = scaleX;
                region.scaleY   = scaleY;
                region.rotation = rotation;
                region.width    = width * scale;
                region.height   = height * scale;
                region.r        = ((color & 0xff000000) >> 24) / 255f;
                region.g        = ((color & 0x00ff0000) >> 16) / 255f;
                region.b        = ((color & 0x0000ff00) >> 8) / 255f;
                region.a        = ((color & 0x000000ff)) / 255f;
                region.UpdateOffset();
                return(region);
            }

            case AttachmentType.Boundingbox: {
                int      vertexCount = ReadVarint(input, true);
                Vertices vertices    = ReadVertices(input, vertexCount);
                if (nonessential)
                {
                    ReadInt(input);                                       //int color = nonessential ? ReadInt(input) : 0; // Avoid unused local warning.
                }
                BoundingBoxAttachment box = attachmentLoader.NewBoundingBoxAttachment(skin, name);
                if (box == null)
                {
                    return(null);
                }
                box.worldVerticesLength = vertexCount << 1;
                box.vertices            = vertices.vertices;
                box.bones = vertices.bones;
                return(box);
            }

            case AttachmentType.Mesh: {
                String   path = ReadString(input);
                int      color = ReadInt(input);
                int      vertexCount = ReadVarint(input, true);
                float[]  uvs = ReadFloatArray(input, vertexCount << 1, 1);
                int[]    triangles = ReadShortArray(input);
                Vertices vertices = ReadVertices(input, vertexCount);
                int      hullLength = ReadVarint(input, true);
                int[]    edges = null;
                float    width = 0, height = 0;
                if (nonessential)
                {
                    edges  = ReadShortArray(input);
                    width  = ReadFloat(input);
                    height = ReadFloat(input);
                }

                if (path == null)
                {
                    path = name;
                }
                MeshAttachment mesh = attachmentLoader.NewMeshAttachment(skin, name, path);
                if (mesh == null)
                {
                    return(null);
                }
                mesh.Path                = path;
                mesh.r                   = ((color & 0xff000000) >> 24) / 255f;
                mesh.g                   = ((color & 0x00ff0000) >> 16) / 255f;
                mesh.b                   = ((color & 0x0000ff00) >> 8) / 255f;
                mesh.a                   = ((color & 0x000000ff)) / 255f;
                mesh.bones               = vertices.bones;
                mesh.vertices            = vertices.vertices;
                mesh.WorldVerticesLength = vertexCount << 1;
                mesh.triangles           = triangles;
                mesh.regionUVs           = uvs;
                mesh.UpdateUVs();
                mesh.HullLength = hullLength << 1;
                if (nonessential)
                {
                    mesh.Edges  = edges;
                    mesh.Width  = width * scale;
                    mesh.Height = height * scale;
                }
                return(mesh);
            }

            case AttachmentType.Linkedmesh: {
                String path = ReadString(input);
                int    color = ReadInt(input);
                String skinName = ReadString(input);
                String parent = ReadString(input);
                bool   inheritDeform = ReadBoolean(input);
                float  width = 0, height = 0;
                if (nonessential)
                {
                    width  = ReadFloat(input);
                    height = ReadFloat(input);
                }

                if (path == null)
                {
                    path = name;
                }
                MeshAttachment mesh = attachmentLoader.NewMeshAttachment(skin, name, path);
                if (mesh == null)
                {
                    return(null);
                }
                mesh.Path          = path;
                mesh.r             = ((color & 0xff000000) >> 24) / 255f;
                mesh.g             = ((color & 0x00ff0000) >> 16) / 255f;
                mesh.b             = ((color & 0x0000ff00) >> 8) / 255f;
                mesh.a             = ((color & 0x000000ff)) / 255f;
                mesh.inheritDeform = inheritDeform;
                if (nonessential)
                {
                    mesh.Width  = width * scale;
                    mesh.Height = height * scale;
                }
                linkedMeshes.Add(new SkeletonJson.LinkedMesh(mesh, skinName, slotIndex, parent));
                return(mesh);
            }

            case AttachmentType.Path: {
                bool     closed        = ReadBoolean(input);
                bool     constantSpeed = ReadBoolean(input);
                int      vertexCount   = ReadVarint(input, true);
                Vertices vertices      = ReadVertices(input, vertexCount);
                float[]  lengths       = new float[vertexCount / 3];
                for (int i = 0, n = lengths.Length; i < n; i++)
                {
                    lengths[i] = ReadFloat(input) * scale;
                }
                if (nonessential)
                {
                    ReadInt(input);                                       //int color = nonessential ? ReadInt(input) : 0;
                }
                PathAttachment path = attachmentLoader.NewPathAttachment(skin, name);
                if (path == null)
                {
                    return(null);
                }
                path.closed              = closed;
                path.constantSpeed       = constantSpeed;
                path.worldVerticesLength = vertexCount << 1;
                path.vertices            = vertices.vertices;
                path.bones   = vertices.bones;
                path.lengths = lengths;
                return(path);
            }

            case AttachmentType.Point: {
                float rotation = ReadFloat(input);
                float x        = ReadFloat(input);
                float y        = ReadFloat(input);
                if (nonessential)
                {
                    ReadInt(input);                                       //int color = nonessential ? ReadInt(input) : 0;
                }
                PointAttachment point = attachmentLoader.NewPointAttachment(skin, name);
                if (point == null)
                {
                    return(null);
                }
                point.x        = x * scale;
                point.y        = y * scale;
                point.rotation = rotation;
                //if (nonessential) point.color = color;
                return(point);
            }

            case AttachmentType.Clipping: {
                int      endSlotIndex = ReadVarint(input, true);
                int      vertexCount  = ReadVarint(input, true);
                Vertices vertices     = ReadVertices(input, vertexCount);
                if (nonessential)
                {
                    ReadInt(input);
                }

                ClippingAttachment clip = attachmentLoader.NewClippingAttachment(skin, name);
                if (clip == null)
                {
                    return(null);
                }
                clip.EndSlot             = skeletonData.slots.Items[endSlotIndex];
                clip.worldVerticesLength = vertexCount << 1;
                clip.vertices            = vertices.vertices;
                clip.bones = vertices.bones;
                return(clip);
            }
            }
            return(null);
        }
        public void Update()
        {
            PathAttachment attachment = target.Attachment as PathAttachment;

            if (attachment == null)
            {
                return;
            }

            float rotateMix = this.rotateMix, translateMix = this.translateMix;
            bool  translate = translateMix > 0, rotate = rotateMix > 0;

            if (!translate && !rotate)
            {
                return;
            }

            PathConstraintData data = this.data;
            SpacingMode        spacingMode = data.spacingMode;
            bool       lengthSpacing = spacingMode == SpacingMode.Length;
            RotateMode rotateMode = data.rotateMode;
            bool       tangents = rotateMode == RotateMode.Tangent, scale = rotateMode == RotateMode.ChainScale;
            int        boneCount = this.bones.Count, spacesCount = tangents ? boneCount : boneCount + 1;

            Bone[] bonesItems = this.bones.Items;
            ExposedList <float> spaces = this.spaces.Resize(spacesCount), lengths = null;
            float spacing = this.spacing;

            if (scale || lengthSpacing)
            {
                if (scale)
                {
                    lengths = this.lengths.Resize(boneCount);
                }
                for (int i = 0, n = spacesCount - 1; i < n;)
                {
                    Bone  bone        = bonesItems[i];
                    float setupLength = bone.data.length;
                    if (setupLength < PathConstraint.Epsilon)
                    {
                        if (scale)
                        {
                            lengths.Items[i] = 0;
                        }
                        spaces.Items[++i] = 0;
                    }
                    else
                    {
                        float x = setupLength * bone.a, y = setupLength * bone.c;
                        float length = (float)Math.Sqrt(x * x + y * y);
                        if (scale)
                        {
                            lengths.Items[i] = length;
                        }
                        spaces.Items[++i] = (lengthSpacing ? setupLength + spacing : spacing) * length / setupLength;
                    }
                }
            }
            else
            {
                for (int i = 1; i < spacesCount; i++)
                {
                    spaces.Items[i] = spacing;
                }
            }

            float[] positions = ComputeWorldPositions(attachment, spacesCount, tangents,
                                                      data.positionMode == PositionMode.Percent, spacingMode == SpacingMode.Percent);
            float boneX = positions[0], boneY = positions[1], offsetRotation = data.offsetRotation;
            bool  tip;

            if (offsetRotation == 0)
            {
                tip = rotateMode == RotateMode.Chain;
            }
            else
            {
                tip = false;
                Bone p = target.bone;
                offsetRotation *= p.a * p.d - p.b * p.c > 0 ? MathUtils.DegRad : -MathUtils.DegRad;
            }
            for (int i = 0, p = 3; i < boneCount; i++, p += 3)
            {
                Bone bone = bonesItems[i];
                bone.worldX += (boneX - bone.worldX) * translateMix;
                bone.worldY += (boneY - bone.worldY) * translateMix;
                float x = positions[p], y = positions[p + 1], dx = x - boneX, dy = y - boneY;
                if (scale)
                {
                    float length = lengths.Items[i];
                    if (length >= PathConstraint.Epsilon)
                    {
                        float s = ((float)Math.Sqrt(dx * dx + dy * dy) / length - 1) * rotateMix + 1;
                        bone.a *= s;
                        bone.c *= s;
                    }
                }
                boneX = x;
                boneY = y;
                if (rotate)
                {
                    float a = bone.a, b = bone.b, c = bone.c, d = bone.d, r, cos, sin;
                    if (tangents)
                    {
                        r = positions[p - 1];
                    }
                    else if (spaces.Items[i + 1] < PathConstraint.Epsilon)
                    {
                        r = positions[p + 2];
                    }
                    else
                    {
                        r = MathUtils.Atan2(dy, dx);
                    }
                    r -= MathUtils.Atan2(c, a);
                    if (tip)
                    {
                        cos = MathUtils.Cos(r);
                        sin = MathUtils.Sin(r);
                        float length = bone.data.length;
                        boneX += (length * (cos * a - sin * c) - dx) * rotateMix;
                        boneY += (length * (sin * a + cos * c) - dy) * rotateMix;
                    }
                    else
                    {
                        r += offsetRotation;
                    }
                    if (r > MathUtils.PI)
                    {
                        r -= MathUtils.PI2;
                    }
                    else if (r < -MathUtils.PI)                     //
                    {
                        r += MathUtils.PI2;
                    }
                    r     *= rotateMix;
                    cos    = MathUtils.Cos(r);
                    sin    = MathUtils.Sin(r);
                    bone.a = cos * a - sin * c;
                    bone.b = cos * b - sin * d;
                    bone.c = sin * a + cos * c;
                    bone.d = sin * b + cos * d;
                }
                bone.appliedValid = false;
            }
        }