Add blend space drawing in Multi Blend 2D editor

#1980

Source/Editor/Surface/Archetypes/Animation.MultiBlend.cs

@@ -30,7 +30,7 @@ namespace FlaxEditor.Surface.Archetypes
         /// Represents single blend point.
         /// </summary>
         /// <seealso cref="FlaxEngine.GUI.Control" />
-        protected class BlendPoint : Control
+        internal class BlendPoint : Control
         {
             private readonly BlendPointsEditor _editor;
             private readonly int _index;
@@ -48,6 +48,11 @@ namespace FlaxEditor.Surface.Archetypes
             /// </summary>
             public int Index => _index;
 
+            /// <summary>
+            /// Flag that indicates that user is moving this point with a mouse.
+            /// </summary>
+            public bool IsMouseDown => _isMouseDown;
+
             /// <summary>
             /// Initializes a new instance of the <see cref="BlendPoint"/> class.
             /// </summary>
@@ -211,6 +216,11 @@ namespace FlaxEditor.Surface.Archetypes
         /// </summary>
         public int PointsCount => (_node.Values.Length - 4) / 2; // 4 node values + 2 per blend point
 
+        /// <summary>
+        /// BLend points array.
+        /// </summary>
+        internal IReadOnlyList<BlendPoint> BlendPoints => _blendPoints;
+
         /// <summary>
         /// Initializes a new instance of the <see cref="BlendPointsEditor"/> class.
         /// </summary>
@@ -374,6 +384,12 @@ namespace FlaxEditor.Surface.Archetypes
         /// <returns>The blend point control position.</returns>
         public Float2 BlendSpacePosToBlendPointPos(Float2 pos)
         {
+            if (_rangeX.IsZero)
+            {
+                var data0 = (Float4)_node.Values[0];
+                _rangeX = new Float2(data0.X, data0.Y);
+                _rangeY = _is2D ? new Float2(data0.Z, data0.W) : Float2.Zero;
+            }
             GetPointsArea(out var pointsArea);
             if (_is2D)
             {
@@ -389,7 +405,7 @@ namespace FlaxEditor.Surface.Archetypes
                                  pointsArea.Center.Y
                                 );
             }
-            return pos - new Float2(BlendPoint.DefaultSize * 0.5f);
+            return pos;
         }
 
         /// <inheritdoc />
@@ -532,81 +548,18 @@ namespace FlaxEditor.Surface.Archetypes
             SetAsset((int)b.Tag, Guid.Empty);
         }
 
-        private void DrawAxis(bool vertical, Float2 start, Float2 end, ref Color gridColor, ref Color labelColor, Font labelFont, float value, bool isLast)
-        {
-            // Draw line
-            Render2D.DrawLine(start, end, gridColor);
-
-            // Draw label
-            var labelWidth = 50.0f;
-            var labelHeight = 10.0f;
-            var labelMargin = 2.0f;
-            string label = Utils.RoundTo2DecimalPlaces(value).ToString(System.Globalization.CultureInfo.InvariantCulture);
-            var hAlign = TextAlignment.Near;
-            Rectangle labelRect;
-            if (vertical)
-            {
-                labelRect = new Rectangle(start.X + labelMargin * 2, start.Y, labelWidth, labelHeight);
-                if (isLast)
-                    return; // Don't overlap with the first horizontal label
-            }
-            else
-            {
-                labelRect = new Rectangle(start.X + labelMargin, start.Y - labelHeight - labelMargin, labelWidth, labelHeight);
-                if (isLast)
-                {
-                    labelRect.X = start.X - labelMargin - labelRect.Width;
-                    hAlign = TextAlignment.Far;
-                }
-            }
-            Render2D.DrawText(labelFont, label, labelRect, labelColor, hAlign, TextAlignment.Center, TextWrapping.NoWrap, 1.0f, 0.7f);
-        }
-
         /// <inheritdoc />
         public override void Draw()
         {
             var style = Style.Current;
             var rect = new Rectangle(Float2.Zero, Size);
             var containsFocus = ContainsFocus;
-            GetPointsArea(out var pointsArea);
-            var data0 = (Float4)_node.Values[0];
-            var rangeX = new Float2(data0.X, data0.Y);
 
             // Background
-            Render2D.DrawRectangle(rect, IsMouseOver ? style.TextBoxBackgroundSelected : style.TextBoxBackground);
+            _node.DrawEditorBackground(ref rect);
-            //Render2D.DrawRectangle(pointsArea, Color.Red);
 
             // Grid
-            int splits = 10;
+            _node.DrawEditorGrid(ref rect);
-            var gridColor = style.TextBoxBackgroundSelected * 1.1f;
-            var labelColor = style.ForegroundDisabled;
-            var labelFont = style.FontSmall;
-            //var blendArea = BlendAreaRect;
-            var blendArea = pointsArea;
-
-            for (int i = 0; i <= splits; i++)
-            {
-                float alpha = (float)i / splits;
-                float x = blendArea.Left + blendArea.Width * alpha;
-                float value = Mathf.Lerp(rangeX.X, rangeX.Y, alpha);
-                DrawAxis(false, new Float2(x, rect.Height - 2), new Float2(x, 1), ref gridColor, ref labelColor, labelFont, value, i == splits);
-            }
-            if (_is2D)
-            {
-                var rangeY = new Float2(data0.Z, data0.W);
-                for (int i = 0; i <= splits; i++)
-                {
-                    float alpha = (float)i / splits;
-                    float y = blendArea.Top + blendArea.Height * alpha;
-                    float value = Mathf.Lerp(rangeY.X, rangeY.Y, 1.0f - alpha);
-                    DrawAxis(true, new Float2(1, y), new Float2(rect.Width - 2, y), ref gridColor, ref labelColor, labelFont, value, i == splits);
-                }
-            }
-            else
-            {
-                float y = blendArea.Center.Y;
-                Render2D.DrawLine(new Float2(1, y), new Float2(rect.Width - 2, y), gridColor);
-            }
 
             base.Draw();
 
@@ -808,6 +761,87 @@ namespace FlaxEditor.Surface.Archetypes
                 _editor.SetAsset(SelectedAnimationIndex, Guid.Empty);
             }
 
+            private void DrawAxis(bool vertical, Float2 start, Float2 end, ref Color gridColor, ref Color labelColor, Font labelFont, float value, bool isLast)
+            {
+                // Draw line
+                Render2D.DrawLine(start, end, gridColor);
+
+                // Draw label
+                var labelWidth = 50.0f;
+                var labelHeight = 10.0f;
+                var labelMargin = 2.0f;
+                string label = Utils.RoundTo2DecimalPlaces(value).ToString(System.Globalization.CultureInfo.InvariantCulture);
+                var hAlign = TextAlignment.Near;
+                Rectangle labelRect;
+                if (vertical)
+                {
+                    labelRect = new Rectangle(start.X + labelMargin * 2, start.Y, labelWidth, labelHeight);
+                    if (isLast)
+                        return; // Don't overlap with the first horizontal label
+                }
+                else
+                {
+                    labelRect = new Rectangle(start.X + labelMargin, start.Y - labelHeight - labelMargin, labelWidth, labelHeight);
+                    if (isLast)
+                    {
+                        labelRect.X = start.X - labelMargin - labelRect.Width;
+                        hAlign = TextAlignment.Far;
+                    }
+                }
+                Render2D.DrawText(labelFont, label, labelRect, labelColor, hAlign, TextAlignment.Center, TextWrapping.NoWrap, 1.0f, 0.7f);
+            }
+
+            /// <summary>
+            /// Custom drawing logic for blend space background.
+            /// </summary>
+            public virtual void DrawEditorBackground(ref Rectangle rect)
+            {
+                var style = Style.Current;
+                Render2D.FillRectangle(rect, style.Background.AlphaMultiplied(0.5f));
+                Render2D.DrawRectangle(rect, IsMouseOver ? style.TextBoxBackgroundSelected : style.TextBoxBackground);
+            }
+
+            /// <summary>
+            /// Custom drawing logic for blend space grid.
+            /// </summary>
+            public virtual void DrawEditorGrid(ref Rectangle rect)
+            {
+                var style = Style.Current;
+                _editor.GetPointsArea(out var pointsArea);
+                var data0 = (Float4)Values[0];
+                var rangeX = new Float2(data0.X, data0.Y);
+                int splits = 10;
+                var gridColor = style.TextBoxBackgroundSelected * 1.1f;
+                var labelColor = style.ForegroundDisabled;
+                var labelFont = style.FontSmall;
+                //var blendArea = BlendAreaRect;
+                var blendArea = pointsArea;
+
+                for (int i = 0; i <= splits; i++)
+                {
+                    float alpha = (float)i / splits;
+                    float x = blendArea.Left + blendArea.Width * alpha;
+                    float value = Mathf.Lerp(rangeX.X, rangeX.Y, alpha);
+                    DrawAxis(false, new Float2(x, rect.Height - 2), new Float2(x, 1), ref gridColor, ref labelColor, labelFont, value, i == splits);
+                }
+                if (_editor.Is2D)
+                {
+                    var rangeY = new Float2(data0.Z, data0.W);
+                    for (int i = 0; i <= splits; i++)
+                    {
+                        float alpha = (float)i / splits;
+                        float y = blendArea.Top + blendArea.Height * alpha;
+                        float value = Mathf.Lerp(rangeY.X, rangeY.Y, 1.0f - alpha);
+                        DrawAxis(true, new Float2(1, y), new Float2(rect.Width - 2, y), ref gridColor, ref labelColor, labelFont, value, i == splits);
+                    }
+                }
+                else
+                {
+                    float y = blendArea.Center.Y;
+                    Render2D.DrawLine(new Float2(1, y), new Float2(rect.Width - 2, y), gridColor);
+                }
+            }
+
             /// <summary>
             /// Updates the editor UI.
             /// </summary>
@@ -972,6 +1006,10 @@ namespace FlaxEditor.Surface.Archetypes
             private readonly FloatValueBox _animationX;
             private readonly Label _animationYLabel;
             private readonly FloatValueBox _animationY;
+            private Float2[] _triangles;
+            private Color[] _triangleColors;
+            private Float2[] _selectedTriangles;
+            private Color[] _selectedColors;
 
             /// <inheritdoc />
             public MultiBlend2D(uint id, VisjectSurfaceContext context, NodeArchetype nodeArch, GroupArchetype groupArch)
@@ -1040,6 +1078,143 @@ namespace FlaxEditor.Surface.Archetypes
                 }
             }
 
+            private void ClearTriangles()
+            {
+                // Remove cache
+                _triangles = null;
+                _triangleColors = null;
+                _selectedTriangles = null;
+                _selectedColors = null;
+            }
+
+            private void CacheTriangles()
+            {
+                // Get locations of blend point vertices
+                int pointsCount = _editor.PointsCount;
+                int count = 0, j = 0;
+                for (int i = 0; i < pointsCount; i++)
+                {
+                    var animId = (Guid)Values[5 + i * 2];
+                    if (animId != Guid.Empty)
+                        count++;
+                }
+                var vertices = new Float2[count];
+                for (int i = 0; i < pointsCount; i++)
+                {
+                    var animId = (Guid)Values[5 + i * 2];
+                    if (animId != Guid.Empty)
+                    {
+                        var dataA = (Float4)Values[4 + i * 2];
+                        vertices[j++] = new Float2(dataA.X, dataA.Y);
+                    }
+                }
+
+                // Triangulate
+                _triangles = FlaxEngine.Utilities.Delaunay2D.Triangulate(vertices);
+                _triangleColors = null;
+
+                // Fix incorrect triangles (mirror logic in AnimGraphBase::onNodeLoaded)
+                if (_triangles == null || _triangles.Length == 0)
+                {
+                    // Insert dummy triangles to have something working (eg. blend points are on the same axis)
+                    var triangles = new List<Float2>();
+                    int verticesLeft = vertices.Length;
+                    while (verticesLeft >= 3)
+                    {
+                        verticesLeft -= 3;
+                        triangles.Add(vertices[verticesLeft + 0]);
+                        triangles.Add(vertices[verticesLeft + 1]);
+                        triangles.Add(vertices[verticesLeft + 2]);
+                    }
+                    if (verticesLeft == 1)
+                    {
+                        triangles.Add(vertices[0]);
+                        triangles.Add(vertices[0]);
+                        triangles.Add(vertices[0]);
+                    }
+                    else if (verticesLeft == 2)
+                    {
+                        triangles.Add(vertices[0]);
+                        triangles.Add(vertices[1]);
+                        triangles.Add(vertices[0]);
+                    }
+                    _triangles = triangles.ToArray();
+                }
+
+                // Project to the blend space for drawing
+                for (int i = 0; i < _triangles.Length; i++)
+                    _triangles[i] = _editor.BlendSpacePosToBlendPointPos(_triangles[i]);
+
+                // Check if anything is selected
+                var selectedIndex = _selectedAnimation.SelectedIndex;
+                if (selectedIndex != -1)
+                {
+                    // Find triangles that contain selected point
+                    var dataA = (Float4)Values[4 + selectedIndex * 2];
+                    var pos = _editor.BlendSpacePosToBlendPointPos(new Float2(dataA.X, dataA.Y));
+                    var selectedTriangles = new List<Float2>();
+                    var selectedColors = new List<Color>();
+                    var style = Style.Current;
+                    var triangleColor = style.TextBoxBackgroundSelected.AlphaMultiplied(0.6f);
+                    var selectedTriangleColor = style.BackgroundSelected.AlphaMultiplied(0.6f);
+                    _triangleColors = new Color[_triangles.Length];
+                    for (int i = 0; i < _triangles.Length; i += 3)
+                    {
+                        var is0 = Float2.NearEqual(ref _triangles[i + 0], ref pos);
+                        var is1 = Float2.NearEqual(ref _triangles[i + 1], ref pos);
+                        var is2 = Float2.NearEqual(ref _triangles[i + 2], ref pos);
+                        if (is0 || is1 || is2)
+                        {
+                            selectedTriangles.Add(_triangles[i + 0]);
+                            selectedTriangles.Add(_triangles[i + 1]);
+                            selectedTriangles.Add(_triangles[i + 2]);
+                            selectedColors.Add(is0 ? Color.White : Color.Transparent);
+                            selectedColors.Add(is1 ? Color.White : Color.Transparent);
+                            selectedColors.Add(is2 ? Color.White : Color.Transparent);
+                        }
+                        _triangleColors[i + 0] = is0 ? selectedTriangleColor : triangleColor;
+                        _triangleColors[i + 1] = is1 ? selectedTriangleColor : triangleColor;
+                        _triangleColors[i + 2] = is2 ? selectedTriangleColor : triangleColor;
+                    }
+                    _selectedTriangles = selectedTriangles.ToArray();
+                    _selectedColors = selectedColors.ToArray();
+                }
+            }
+
+            /// <inheritdoc />
+            public override void DrawEditorBackground(ref Rectangle rect)
+            {
+                base.DrawEditorBackground(ref rect);
+
+                // Draw triangulated multi blend space
+                var style = Style.Current;
+                if (_triangles == null)
+                    CacheTriangles();
+                if (_triangleColors != null && (ContainsFocus || IsMouseOver))
+                    Render2D.FillTriangles(_triangles, _triangleColors);
+                else
+                    Render2D.FillTriangles(_triangles, style.TextBoxBackgroundSelected.AlphaMultiplied(0.6f));
+                Render2D.DrawTriangles(_triangles, style.Foreground);
+            }
+
+            /// <inheritdoc />
+            public override void DrawEditorGrid(ref Rectangle rect)
+            {
+                base.DrawEditorGrid(ref rect);
+
+                // Highlight selected blend point
+                var style = Style.Current;
+                var selectedIndex = _selectedAnimation.SelectedIndex;
+                if (selectedIndex != -1 && (ContainsFocus || IsMouseOver))
+                {
+                    var point = _editor.BlendPoints[selectedIndex];
+                    var highlightColor = point.IsMouseDown ? style.SelectionBorder : style.BackgroundSelected;
+                    Render2D.PushTint(ref highlightColor);
+                    Render2D.DrawTriangles(_selectedTriangles, _selectedColors);
+                    Render2D.PopTint();
+                }
+            }
+
             /// <inheritdoc />
             public override void UpdateUI(int selectedIndex, bool isValid, ref Float4 data0, ref Guid data1)
             {
@@ -1064,6 +1239,23 @@ namespace FlaxEditor.Surface.Archetypes
                 _animationX.Enabled = isValid;
                 _animationYLabel.Enabled = isValid;
                 _animationY.Enabled = isValid;
+                ClearTriangles();
+            }
+
+            /// <inheritdoc />
+            public override void OnValuesChanged()
+            {
+                base.OnValuesChanged();
+
+                ClearTriangles();
+            }
+
+            /// <inheritdoc />
+            public override void OnLoaded(SurfaceNodeActions action)
+            {
+                base.OnLoaded(action);
+
+                ClearTriangles();
             }
         }
     }

Source/Engine/Render2D/Render2D.cpp

@@ -301,12 +301,12 @@ void WriteTri(const Float2& p0, const Float2& p1, const Float2& p2, const Float2
     IBIndex += 3;
 }
 
-void WriteTri(const Float2& p0, const Float2& p1, const Float2& p2, const Color& color0, const Color& color1, const Color& color2)
+FORCE_INLINE void WriteTri(const Float2& p0, const Float2& p1, const Float2& p2, const Color& color0, const Color& color1, const Color& color2)
 {
     WriteTri(p0, p1, p2, Float2::Zero, Float2::Zero, Float2::Zero, color0, color1, color2);
 }
 
-void WriteTri(const Float2& p0, const Float2& p1, const Float2& p2, const Float2& uv0, const Float2& uv1, const Float2& uv2)
+FORCE_INLINE void WriteTri(const Float2& p0, const Float2& p1, const Float2& p2, const Float2& uv0, const Float2& uv1, const Float2& uv2)
 {
     WriteTri(p0, p1, p2, uv0, uv1, uv2, Color::Black, Color::Black, Color::Black);
 }
@@ -1816,8 +1816,8 @@ void DrawLines(const Float2* points, int32 pointsCount, const Color& color1, con
 
     // Ending cap
     {
-        ApplyTransform(points[0], p1t);
+        ApplyTransform(points[pointsCount - 2], p1t);
-        ApplyTransform(points[1], p2t);
+        //ApplyTransform(points[pointsCount - 1], p2t);
 
         const Float2 capDirection = thicknessHalf * Float2::Normalize(p2t - p1t);
 
@@ -1962,9 +1962,56 @@ void Render2D::DrawBlur(const Rectangle& rect, float blurStrength)
     WriteRect(rect, Color::White);
 }
 
+void Render2D::DrawTriangles(const Span<Float2>& vertices, const Color& color, float thickness)
+{
+    RENDER2D_CHECK_RENDERING_STATE;
+    CHECK(vertices.Length() % 3 == 0);
+
+    Float2 points[2];
+    for (int32 i = 0; i < vertices.Length(); i += 3)
+    {
+#if 0
+        // TODO: fix this
+        DrawLines(&vertices.Get()[i], 3, color, color, thickness);
+#else
+        points[0] = vertices.Get()[i + 0];
+        points[1] = vertices.Get()[i + 1];
+        DrawLines(points, 2, color, color, thickness);
+        points[0] = vertices.Get()[i + 2];
+        DrawLines(points, 2, color, color, thickness);
+        points[1] = vertices.Get()[i + 0];
+        DrawLines(points, 2, color, color, thickness);
+#endif
+    }
+}
+
+void Render2D::DrawTriangles(const Span<Float2>& vertices, const Span<Color>& colors, float thickness)
+{
+    RENDER2D_CHECK_RENDERING_STATE;
+    CHECK(vertices.Length() % 3 == 0);
+
+    Float2 points[2];
+    Color cols[2];
+    for (int32 i = 0; i < vertices.Length(); i += 3)
+    {
+        points[0] = vertices.Get()[i + 0];
+        points[1] = vertices.Get()[i + 1];
+        cols[0] = colors.Get()[i + 0];
+        cols[1] = colors.Get()[i + 1];
+        DrawLines(points, 2, cols[0], cols[1], thickness);
+        points[0] = vertices.Get()[i + 2];
+        cols[0] = colors.Get()[i + 2];
+        DrawLines(points, 2, cols[0], cols[1], thickness);
+        points[1] = vertices.Get()[i + 0];
+        cols[1] = colors.Get()[i + 0];
+        DrawLines(points, 2, cols[0], cols[1], thickness);
+    }
+}
+
 void Render2D::DrawTexturedTriangles(GPUTexture* t, const Span<Float2>& vertices, const Span<Float2>& uvs)
 {
     RENDER2D_CHECK_RENDERING_STATE;
+    CHECK(vertices.Length() % 3 == 0);
     CHECK(vertices.Length() == uvs.Length());
 
     Render2DDrawCall& drawCall = DrawCalls.AddOne();
@@ -1979,14 +2026,24 @@ void Render2D::DrawTexturedTriangles(GPUTexture* t, const Span<Float2>& vertices
 
 void Render2D::DrawTexturedTriangles(GPUTexture* t, const Span<Float2>& vertices, const Span<Float2>& uvs, const Color& color)
 {
-    Color colors[3] = { (Color)color, (Color)color, (Color)color };
+    RENDER2D_CHECK_RENDERING_STATE;
-    Span<Color> spancolor(colors, 3);
+    CHECK(vertices.Length() % 3 == 0);
-    DrawTexturedTriangles(t, vertices, uvs, spancolor);
+    CHECK(vertices.Length() == uvs.Length());
+
+    Render2DDrawCall& drawCall = DrawCalls.AddOne();
+    drawCall.Type = DrawCallType::FillTexture;
+    drawCall.StartIB = IBIndex;
+    drawCall.CountIB = vertices.Length();
+    drawCall.AsTexture.Ptr = t;
+
+    for (int32 i = 0; i < vertices.Length(); i += 3)
+        WriteTri(vertices[i], vertices[i + 1], vertices[i + 2], uvs[i], uvs[i + 1], uvs[i + 2], color, color, color);
 }
 
 void Render2D::DrawTexturedTriangles(GPUTexture* t, const Span<Float2>& vertices, const Span<Float2>& uvs, const Span<Color>& colors)
 {
     RENDER2D_CHECK_RENDERING_STATE;
+    CHECK(vertices.Length() % 3 == 0);
     CHECK(vertices.Length() == uvs.Length());
     CHECK(vertices.Length() == colors.Length());
 
@@ -2021,6 +2078,19 @@ void Render2D::DrawTexturedTriangles(GPUTexture* t, const Span<uint16>& indices,
     }
 }
 
+void Render2D::FillTriangles(const Span<Float2>& vertices, const Color& color)
+{
+    RENDER2D_CHECK_RENDERING_STATE;
+
+    Render2DDrawCall& drawCall = DrawCalls.AddOne();
+    drawCall.Type = NeedAlphaWithTint(color) ? DrawCallType::FillRect : DrawCallType::FillRectNoAlpha;
+    drawCall.StartIB = IBIndex;
+    drawCall.CountIB = vertices.Length();
+
+    for (int32 i = 0; i < vertices.Length(); i += 3)
+        WriteTri(vertices[i], vertices[i + 1], vertices[i + 2], color, color, color);
+}
+
 void Render2D::FillTriangles(const Span<Float2>& vertices, const Span<Color>& colors, bool useAlpha)
 {
     CHECK(vertices.Length() == colors.Length());

Source/Engine/Render2D/Render2D.h

@@ -415,6 +415,22 @@ public:
     /// <param name="blurStrength">The blur strength defines how blurry the background is. Larger numbers increase blur, resulting in a larger runtime cost on the GPU.</param>
     API_FUNCTION() static void DrawBlur(const Rectangle& rect, float blurStrength);
 
+    /// <summary>
+    /// Draws vertices array.
+    /// </summary>
+    /// <param name="vertices">The vertices array.</param>
+    /// <param name="color">The color.</param>
+    /// <param name="thickness">The line thickness.</param>
+    API_FUNCTION() static void DrawTriangles(const Span<Float2>& vertices, const Color& color, float thickness = 1.0f);
+
+    /// <summary>
+    /// Draws vertices array.
+    /// </summary>
+    /// <param name="vertices">The vertices array.</param>
+    /// <param name="colors">The colors array.</param>
+    /// <param name="thickness">The line thickness.</param>
+    API_FUNCTION() static void DrawTriangles(const Span<Float2>& vertices, const Span<Color>& colors, float thickness = 1.0f);
+
     /// <summary>
     /// Draws vertices array.
     /// </summary>
@@ -451,13 +467,20 @@ public:
     /// <param name="colors">The colors array.</param>
     API_FUNCTION() static void DrawTexturedTriangles(GPUTexture* t, const Span<uint16>& indices, const Span<Float2>& vertices, const Span<Float2>& uvs, const Span<Color>& colors);
 
+    /// <summary>
+    /// Draws vertices array.
+    /// </summary>
+    /// <param name="vertices">The vertices array.</param>
+    /// <param name="color">The color.</param>
+    API_FUNCTION() static void FillTriangles(const Span<Float2>& vertices, const Color& color);
+
     /// <summary>
     /// Draws vertices array.
     /// </summary>
     /// <param name="vertices">The vertices array.</param>
     /// <param name="colors">The colors array.</param>
     /// <param name="useAlpha">If true alpha blending will be enabled.</param>
-    API_FUNCTION() static void FillTriangles(const Span<Float2>& vertices, const Span<Color>& colors, bool useAlpha);
+    API_FUNCTION() static void FillTriangles(const Span<Float2>& vertices, const Span<Color>& colors, bool useAlpha = true);
 
     /// <summary>
     /// Fills a triangular area.

Source/Engine/Utilities/Delaunay2D.h

@@ -7,10 +7,11 @@
 #include "Engine/Core/Collections/Array.h"
 
 /// <summary>
-/// Helper class with Delaunay triangulation algorithm implementation,
+/// Helper class with Delaunay triangulation algorithm implementation (2D space).
 /// </summary>
-class Delaunay2D
+API_CLASS(Internal, Static, Namespace="FlaxEngine.Utilities") class Delaunay2D
 {
+    DECLARE_SCRIPTING_TYPE_MINIMAL(Delaunay2D);
 public:
     struct Triangle
     {
@@ -31,14 +32,35 @@ public:
         }
     };
 
-    template<typename TVertexArray, typename TTrianglesArray>
+    /// <summary>
-    static void Triangulate(const TVertexArray& vertices, TTrianglesArray& triangles)
+    /// Triangulates input vertices array into the list of triangle vertices.
+    /// </summary>
+    /// <param name="vertices">Input list of vertices.</param>
+    /// <returns>Result list of triangles. Each triangle is made out of sequence of 3 vertices. Empty if no valid triangle built.</returns>
+    API_FUNCTION() static Array<Float2> Triangulate(const Array<Float2>& vertices)
+    {
+        Array<Triangle> triangles;
+        Triangulate(vertices, triangles);
+        Array<Float2> result;
+        result.Resize(triangles.Count() * 3);
+        int32 c = 0;
+        for (const Triangle& t : triangles)
+        {
+            result.Get()[c++] = vertices[t.Indices[0]];
+            result.Get()[c++] = vertices[t.Indices[1]];
+            result.Get()[c++] = vertices[t.Indices[2]];
+        }
+        return result;
+    }
+
+    template<typename TrianglesArray = Triangle>
+    static void Triangulate(const Array<Float2>& vertices, TrianglesArray& triangles)
     {
         // Skip if no change to produce any triangles
-        if (vertices.Count() < 3)
+         if (vertices.Count() < 3)
             return;
 
-        TVertexArray points = vertices;
+        Array<Float2> points = vertices;
         Array<Edge> polygon;
 
         Rectangle rect;
@@ -142,8 +164,7 @@ private:
         }
     };
 
-    template<typename TVertexArray>
+    static bool CircumCircleContains(const Array<Float2>& vertices, const Triangle& triangle, int32 vertexIndex)
-    static bool CircumCircleContains(const TVertexArray& vertices, const Triangle& triangle, int vertexIndex)
     {
         Float2 p1 = vertices[triangle.Indices[0]];
         Float2 p2 = vertices[triangle.Indices[1]];
@@ -157,25 +178,20 @@ private:
             (ab * (p3.Y - p2.Y) + cd * (p1.Y - p3.Y) + ef * (p2.Y - p1.Y)) / (p1.X * (p3.Y - p2.Y) + p2.X * (p1.Y - p3.Y) + p3.X * (p2.Y - p1.Y)),
             (ab * (p3.X - p2.X) + cd * (p1.X - p3.X) + ef * (p2.X - p1.X)) / (p1.Y * (p3.X - p2.X) + p2.Y * (p1.X - p3.X) + p3.Y * (p2.X - p1.X)));
 
-        circum *= 0.5;
+        circum *= 0.5f;
         float r = Float2::DistanceSquared(p1, circum);
         float d = Float2::DistanceSquared(vertices[vertexIndex], circum);
         return d <= r;
     }
 
-    template<typename TVertexArray>
+    static bool EdgeCompare(const Array<Float2>& vertices, const Edge& a, const Edge& b)
-    static bool EdgeCompare(const TVertexArray& vertices, const Edge& a, const Edge& b)
     {
-        if (Float2::Distance(vertices[a.Indices[0]], vertices[b.Indices[0]]) < ZeroTolerance && Vector2::Distance(vertices[a.Indices[1]], vertices[b.Indices[1]]) < ZeroTolerance)
+        if (Float2::Distance(vertices[a.Indices[0]], vertices[b.Indices[0]]) < ZeroTolerance && 
-        {
+            Float2::Distance(vertices[a.Indices[1]], vertices[b.Indices[1]]) < ZeroTolerance)
             return true;
-        }
+        if (Float2::Distance(vertices[a.Indices[0]], vertices[b.Indices[1]]) < ZeroTolerance && 
-
+            Float2::Distance(vertices[a.Indices[1]], vertices[b.Indices[0]]) < ZeroTolerance)
-        if (Float2::Distance(vertices[a.Indices[0]], vertices[b.Indices[1]]) < ZeroTolerance && Vector2::Distance(vertices[a.Indices[1]], vertices[b.Indices[0]]) < ZeroTolerance)
-        {
             return true;
-        }
-
         return false;
     }
 };