Relocate Matrix/Vector code to lib where plugins can use it

Also, tweak the perspective projection scaling to fill out the area
a bit more, and change the visualization editor to use the grid's
size when setting the path dimensions.

Also, note gimbal lock.

PluginCommon/Matrix44.cs

@@ -0,0 +1,124 @@
+/*
+ * Copyright 2020 faddenSoft
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace PluginCommon {
+    /// <summary>
+    /// Simple 4x4 matrix.
+    /// </summary>
+    public class Matrix44 {
+        public double[,] Val {
+            get { return mVal; }
+            private set { mVal = value; }
+        }
+        private double[,] mVal;
+
+        public Matrix44() {
+            Val = new double[4, 4];
+        }
+
+        public void Clear() {
+            for (int col = 0; col < 4; col++) {
+                for (int row = 0; row < 4; row++) {
+                    Val[col, row] = 0.0;
+                }
+            }
+        }
+
+        public void SetToIdentity() {
+            Clear();
+            Val[0, 0] = Val[1, 1] = Val[2, 2] = Val[3, 3] = 1.0;
+        }
+
+        /// <summary>
+        /// Sets the matrix to perform rotation about Euler angles in the order X, Y, Z.
+        /// </summary>
+        /// <param name="xdeg">Rotation about the X axis, in degrees.</param>
+        /// <param name="ydeg">Rotation about the Y axis, in degrees.</param>
+        /// <param name="zdeg">Rotation about the Z axis, in degrees.</param>
+        public void SetRotationEuler(int xdeg, int ydeg, int zdeg) {
+            const double degToRad = Math.PI / 180.0;
+            double xrad = xdeg * degToRad;
+            double yrad = ydeg * degToRad;
+            double zrad = zdeg * degToRad;
+
+            double cx = Math.Cos(xrad);
+            double sx = Math.Sin(xrad);
+            double cy = Math.Cos(yrad);
+            double sy = Math.Sin(yrad);
+            double cz = Math.Cos(zrad);
+            double sz = Math.Sin(zrad);
+            double sycx = sy * cx;
+            double sysx = sy * sx;
+
+            bool useXyz = true;
+            if (useXyz) {
+                // R = Rz * Ry * Rx (from wikipedia)
+                Val[0, 0] = cz * cy;
+                Val[0, 1] = sz * cy;
+                Val[0, 2] = -sy;
+
+                Val[1, 0] = cz * sysx - sz * cx;
+                Val[1, 1] = sz * sysx + cz * cx;
+                Val[1, 2] = cy * sx;
+
+                Val[2, 0] = cz * sycx + sz * sx;
+                Val[2, 1] = sz * sycx - cz * sx;
+                Val[2, 2] = cy * cx;
+            } else {
+                // R = Rx * Ry * Rz (from Arc3D)
+                Val[0, 0] = cz * cy;
+                Val[0, 1] = -sz * cy;
+                Val[0, 2] = sy;
+
+                Val[1, 0] = cz * sysx + sz * cx;
+                Val[1, 1] = -sz * sysx + cz * cx;
+                Val[1, 2] = -cy * sx;
+
+                Val[2, 0] = -cz * sycx + sz * sx;
+                Val[2, 1] = sz * sycx + cz * sx;
+                Val[2, 2] = cy * cx;
+            }
+            //Val[0, 3] = Val[1, 3] = Val[2, 3] = Val[3, 0] = Val[3, 1] = Val[3, 2] = 0.0;
+            Val[3, 3] = 1.0;
+        }
+
+        /// <summary>
+        /// Multiplies a 3-element vector.  The vector's 4th element is implicitly set to 1.
+        /// </summary>
+        /// <param name="vec">Column vector to multiply.</param>
+        /// <returns>Result vector.</returns>
+        public Vector3 Multiply(Vector3 vec) {
+            double rx = vec.X * Val[0, 0] + vec.Y * Val[1, 0] + vec.Z * Val[2, 0] + Val[3, 0];
+            double ry = vec.X * Val[0, 1] + vec.Y * Val[1, 1] + vec.Z * Val[2, 1] + Val[3, 1];
+            double rz = vec.X * Val[0, 2] + vec.Y * Val[1, 2] + vec.Z * Val[2, 2] + Val[3, 2];
+            return new Vector3(rx, ry, rz);
+        }
+
+
+        public override string ToString() {
+            StringBuilder sb = new StringBuilder();
+            for (int row = 0; row < 4; row++) {
+                sb.AppendFormat("|{0,8:N3} {1,8:N3} {2,8:N3} {3,8:N3}|",
+                    Val[0, row], Val[1, row], Val[2, row], Val[3, row]);
+                sb.AppendLine();
+            }
+            return sb.ToString();
+        }
+    }
+}

PluginCommon/Vector3.cs

@@ -0,0 +1,69 @@
+/*
+ * Copyright 2020 faddenSoft
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+using System;
+
+namespace PluginCommon {
+    /// <summary>
+    /// Simple 3-element column vector.
+    /// </summary>
+    public class Vector3 {
+        public double X {
+            get { return mX; }
+            set { mX = value; }
+        }
+        public double Y {
+            get { return mY; }
+            set { mY = value; }
+        }
+        public double Z {
+            get { return mZ; }
+            set { mZ = value; }
+        }
+        private double mX, mY, mZ;
+
+        public Vector3(double x, double y, double z) {
+            mX = x;
+            mY = y;
+            mZ = z;
+        }
+
+        public double Magnitude() {
+            return Math.Sqrt(X * X + Y * Y + Z * Z);
+        }
+
+        public void Normalize() {
+            double len_r = 1.0 / Magnitude();
+            mX *= len_r;
+            mY *= len_r;
+            mZ *= len_r;
+        }
+
+        public void Multiply(double sc) {
+            mX *= sc;
+            mY *= sc;
+            mZ *= sc;
+        }
+
+        public static double Dot(Vector3 v0, Vector3 v1) {
+            return v0.X * v1.X + v0.Y * v1.Y + v0.Z * v1.Z;
+        }
+
+
+        public override string ToString() {
+            return string.Format("|{0,8:N3} {1,8:N3} {2,8:N3}|", X, Y, Z);
+        }
+    }
+}

PluginCommon/VisWireframe.cs

@@ -172,8 +172,9 @@ namespace PluginCommon {
                 }
             }
 
-            // TODO(maybe): confirm that every face has a vertex.  Not strictly necessary
-            // since you can do orthographic-projection BFC without it... but who does that?
+            // TODO(maybe): confirm that every face (i.e. normal) has a vertex we can use for
+            // BFC calculation.  Not strictly necessary since you can do orthographic-projection
+            // BFC without it... but who does that?
 
             msg = string.Empty;
             return true;