Add utility class to generate procedural meshes

Author: adamgraham

Runtime/MeshGenerator.cs

@@ -0,0 +1,137 @@
+using UnityEngine;
+using UnityEngine.Rendering;
+
+namespace Zigurous.Graphics
+{
+    /// <summary>
+    /// Utility class to generate procedural meshes at runtime.
+    /// </summary>
+    public static class MeshGenerator
+    {
+        public delegate Vector3 VertexGenerator(int x, int y, float u, float v);
+
+        /// <summary>
+        /// Creates a new procedural mesh of a grid of points.
+        /// </summary>
+        /// <param name="width">The width of the grid of points.</param>
+        /// <param name="height">The height of the grid of points.</param>
+        public static Mesh Create(int width, int height)
+        {
+            Mesh mesh = new Mesh();
+
+            if (width * height > 65535) {
+                mesh.indexFormat = IndexFormat.UInt32;
+            }
+
+            mesh.vertices = CreateVertices(width, height, DefaultVertexGenerator);
+            mesh.triangles = CreateTriangles(width, height);
+            mesh.uv = CreateUVs(width, height);
+            mesh.RecalculateNormals();
+
+            return mesh;
+        }
+
+        /// <summary>
+        /// Creates a new procedural mesh using a custom vertex function.
+        /// </summary>
+        /// <param name="width">The width of the grid of points.</param>
+        /// <param name="height">The height of the grid of points.</param>
+        /// <param name="vertexGenerator">A custom function to calculate the vertex for a given point.</param>
+        public static Mesh Create(int width, int height, VertexGenerator vertexGenerator)
+        {
+            if (vertexGenerator == null) {
+                vertexGenerator = DefaultVertexGenerator;
+            }
+
+            Mesh mesh = new Mesh();
+
+            if (width * height > 65535) {
+                mesh.indexFormat = IndexFormat.UInt32;
+            }
+
+            mesh.vertices = CreateVertices(width, height, vertexGenerator);
+            mesh.triangles = CreateTriangles(width, height);
+            mesh.uv = CreateUVs(width, height);
+            mesh.RecalculateNormals();
+
+            return mesh;
+        }
+
+        private static Vector3[] CreateVertices(int width, int height, VertexGenerator vertexGenerator)
+        {
+            Vector3[] verticies = new Vector3[(width + 1) * (height + 1)];
+
+            int index = 0;
+
+            for (int y = 0; y <= height; y++)
+            {
+                for (int x = 0; x <= width; x++)
+                {
+                    float u = x / (float)width;
+                    float v = y / (float)height;
+
+                    verticies[index] = vertexGenerator(x, y, u, v);
+                    index++;
+                }
+            }
+
+            return verticies;
+        }
+
+        private static int[] CreateTriangles(int width, int height)
+        {
+            int[] triangles = new int[width * height * 6];
+
+            int vert = 0;
+            int tris = 0;
+
+            for (int y = 0; y < height; y++)
+            {
+                for (int x = 0; x < width; x++)
+                {
+                    triangles[tris + 0] = vert + 0;
+                    triangles[tris + 1] = vert + width + 1;
+                    triangles[tris + 2] = vert + 1;
+                    triangles[tris + 3] = vert + 1;
+                    triangles[tris + 4] = vert + width + 1;
+                    triangles[tris + 5] = vert + width + 2;
+
+                    vert++;
+                    tris += 6;
+                }
+
+                vert++;
+            }
+
+            return triangles;
+        }
+
+        private static Vector2[] CreateUVs(int width, int height)
+        {
+            Vector2[] uvs = new Vector2[(width + 1) * (height + 1)];
+
+            int index = 0;
+
+            for (int y = 0; y <= height; y++)
+            {
+                for (int x = 0; x <= width; x++)
+                {
+                    float u = x / (float)width;
+                    float v = y / (float)height;
+
+                    uvs[index] = new Vector2(u, v);
+                    index++;
+                }
+            }
+
+            return uvs;
+        }
+
+        private static Vector3 DefaultVertexGenerator(int x, int y, float u, float v)
+        {
+            return new Vector3(x, 0f, y);
+        }
+
+    }
+
+}