[Mathematics] fix bug in Collision.ClosestPointPointTriangle()

Author: AndrewSt

Source/SharpDX.Mathematics/Collision.cs

@@ -97,36 +97,47 @@ public static void ClosestPointPointTriangle(ref Vector3 point, ref Vector3 vert
             float d1 = Vector3.Dot(ab, ap);
             float d2 = Vector3.Dot(ac, ap);
             if (d1 <= 0.0f && d2 <= 0.0f)
+            {
                 result = vertex1; //Barycentric coordinates (1,0,0)
+                return;
+            }
 
             //Check if P in vertex region outside B
             Vector3 bp = point - vertex2;
             float d3 = Vector3.Dot(ab, bp);
             float d4 = Vector3.Dot(ac, bp);
             if (d3 >= 0.0f && d4 <= d3)
+            {
                 result = vertex2; // Barycentric coordinates (0,1,0)
+                return;
+            }
 
             //Check if P in edge region of AB, if so return projection of P onto AB
             float vc = d1 * d4 - d3 * d2;
             if (vc <= 0.0f && d1 >= 0.0f && d3 <= 0.0f)
             {
                 float v = d1 / (d1 - d3);
                 result = vertex1 + v * ab; //Barycentric coordinates (1-v,v,0)
+                return;
             }
 
             //Check if P in vertex region outside C
             Vector3 cp = point - vertex3;
             float d5 = Vector3.Dot(ab, cp);
             float d6 = Vector3.Dot(ac, cp);
             if (d6 >= 0.0f && d5 <= d6)
+            {
                 result = vertex3; //Barycentric coordinates (0,0,1)
+                return;
+            }
 
             //Check if P in edge region of AC, if so return projection of P onto AC
             float vb = d5 * d2 - d1 * d6;
             if (vb <= 0.0f && d2 >= 0.0f && d6 <= 0.0f)
             {
                 float w = d2 / (d2 - d6);
                 result = vertex1 + w * ac; //Barycentric coordinates (1-w,0,w)
+                return;
             }
 
             //Check if P in edge region of BC, if so return projection of P onto BC
@@ -135,6 +146,7 @@ public static void ClosestPointPointTriangle(ref Vector3 point, ref Vector3 vert
             {
                 float w = (d4 - d3) / ((d4 - d3) + (d5 - d6));
                 result = vertex2 + w * (vertex3 - vertex2); //Barycentric coordinates (0,1-w,w)
+                return;
             }
 
             //P inside face region. Compute Q through its Barycentric coordinates (u,v,w)

Source/Tests/SharpDX.Tests/MathCollisionTest.cs

@@ -0,0 +1,47 @@
+// Copyright (c) 2010-2013 SharpDX - Alexandre Mutel
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+using NUnit.Framework;
+
+namespace SharpDX.Tests
+{
+    [TestFixture]
+    public class MathCollisionTest
+    {
+        [Test]
+        public void ClosestPointPointTriangleTest()
+        {
+            Assert.AreEqual(ClosestPointPointTriangle(new Vector3(0, 0, 0), new Vector3(1, 1, 0), new Vector3(2, 2, 0), new Vector3(3, 1, 0)), new Vector3(1, 1, 0));
+            Assert.AreEqual(ClosestPointPointTriangle(new Vector3(1, 1, 0), new Vector3(1, 1, 0), new Vector3(2, 2, 0), new Vector3(3, 1, 0)), new Vector3(1, 1, 0));
+            Assert.AreEqual(ClosestPointPointTriangle(new Vector3(2, 3, 0), new Vector3(1, 1, 0), new Vector3(2, 2, 0), new Vector3(3, 1, 0)), new Vector3(2, 2, 0));
+            Assert.AreEqual(ClosestPointPointTriangle(new Vector3(4, 1, 0), new Vector3(1, 1, 0), new Vector3(2, 2, 0), new Vector3(3, 1, 0)), new Vector3(3, 1, 0));
+            Assert.AreEqual(ClosestPointPointTriangle(new Vector3(1, 2, 0), new Vector3(1, 1, 0), new Vector3(2, 2, 0), new Vector3(3, 1, 0)), new Vector3(1.5f, 1.5f, 0));
+            Assert.AreEqual(ClosestPointPointTriangle(new Vector3(3, 2, 0), new Vector3(1, 1, 0), new Vector3(2, 2, 0), new Vector3(3, 1, 0)), new Vector3(2.5f, 1.5f, 0));
+            Assert.AreEqual(ClosestPointPointTriangle(new Vector3(2, 0, 0), new Vector3(1, 1, 0), new Vector3(2, 2, 0), new Vector3(3, 1, 0)), new Vector3(2, 1, 0));
+
+            Assert.AreEqual(ClosestPointPointTriangle(new Vector3(2, 1.5f, 1), new Vector3(1, 1, 0), new Vector3(2, 2, 0), new Vector3(3, 1, 0)), new Vector3(2, 1.5f, 0));
+        }
+        private static Vector3 ClosestPointPointTriangle(Vector3 point, Vector3 vertex1, Vector3 vertex2, Vector3 vertex3)
+        {
+            Vector3 result;
+            Collision.ClosestPointPointTriangle(ref point, ref vertex1, ref vertex2, ref vertex3, out result);
+            return result;
+        }
+    }
+}

Source/Tests/SharpDX.Tests/SharpDX.Tests.csproj

@@ -46,6 +46,7 @@
     <Reference Include="System.Xml" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="MathCollisionTest.cs" />
     <Compile Include="MathUtilNearEqualTests.cs" />
     <Compile Include="MathUtilWrapTests.cs" />
     <Compile Include="RayTests.cs" />