Game gizmos

Author: ElasticSea

Scripts/Util/GameGizmoUtils.cs

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+using System.Collections.Generic;
+using System.Linq;
+using ElasticSea.Framework.Extensions;
+using UnityEngine;
+
+namespace ElasticSea.Framework.Scripts.Util
+{
+    public class GameGizmoUtils
+    {
+        public static GameObject DrawArrow(Vector3 from, Vector3 to, float arrowHeadLength, Color bottom, Color top, float killDelay = 0f)
+        {
+            var go = new GameObject("Arrow");
+            go.AddComponent<MeshFilter>().mesh = BuildArrowMesh(to.Distance(from), arrowHeadLength, bottom, top);
+            go.AddComponent<MeshRenderer>().material = new Material(Shader.Find("Unlit/Vertex Color"));
+            go.transform.position = from;
+            go.transform.LookAt(to);
+            go.transform.rotation *= Quaternion.Euler(90, 0, 0);
+
+            if (killDelay > 0)
+            {
+                Object.Destroy(go, killDelay);
+            }
+            return go;
+        }
+
+        private static Mesh BuildArrowMesh(float distance, float arrowHeadLength, Color bottom, Color top)
+        {
+            var arrowHeadRadius = arrowHeadLength / 2.5f;
+            var arrowLength = distance - arrowHeadLength;
+            var segments = 32;
+            var lineRadius = arrowHeadRadius / 4;
+
+            var points = new List<Vector3>();
+            var segment = Mathf.PI * 2 / segments;
+            for (int i = 0; i < segments; i++)
+            {
+                var x = Mathf.Cos(segment * i) * arrowHeadRadius;
+                var y = Mathf.Sin(segment * i) * arrowHeadRadius;
+                points.Add(new Vector3(x, arrowLength, y));
+            }
+
+            var meshBuilder = new MeshBuilder();
+
+            // arrow head
+            meshBuilder.AddCircle(points.ToArray(), new Vector3(0, arrowLength + arrowHeadLength, 0));
+            meshBuilder.AddCircle(points.ToArray(), new Vector3(0, arrowLength, 0), true);
+
+            var points2 = new List<Vector3>();
+            for (int i = 0; i < segments; i++)
+            {
+                var x = Mathf.Cos(segment * i) * lineRadius;
+                var y = Mathf.Sin(segment * i) * lineRadius;
+                points2.Add(new Vector3(x, 0, y));
+            }
+
+            var pointsBottom = points2.Select(p => new Vector3(p.x, arrowLength, p.z)).ToArray();
+            meshBuilder.AddStrip(points2.ToArray(), pointsBottom);
+            meshBuilder.AddCircle(points2.ToArray(), new Vector3(0, 0, 0), true);
+            var buildArrow = meshBuilder.GetMesh();
+            buildArrow.colors = buildArrow.vertices.Select(v => Color.Lerp(bottom, top, v.y / distance)).ToArray();
+            return buildArrow;
+        }
+    }
+}

Scripts/Util/GameGizmoUtils.cs.meta

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+using System;
+using System.Collections.Generic;
+using UnityEngine;
+
+namespace ElasticSea.Framework.Scripts.Util
+{
+    public class MeshBuilder
+    {
+        private List<Vector3> vertices = new();
+        private List<int> triangles = new();
+
+        public void AddTriangle(Vector3 p0, Vector3 p1, Vector3 p2, bool flip = false)
+        {
+            var vCount = vertices.Count;
+            if (flip)
+            {
+                (p2, p1) = (p1, p2);
+            }
+
+            vertices.Add(p0);
+            vertices.Add(p1);
+            vertices.Add(p2);
+            triangles.Add(vCount + 0);
+            triangles.Add(vCount + 1);
+            triangles.Add(vCount + 2);
+        }
+
+        public void AddQuad(Vector3 p0, Vector3 p1, Vector3 p2, Vector3 p3, bool flip = false)
+        {
+            AddTriangle(p0, p1, p2, flip);
+            AddTriangle(p0, p2, p3, flip);
+        }
+
+        public void AddStrip(Vector3[] points0, Vector3[] points1, bool flip = false)
+        {
+            if (points0.Length != points1.Length)
+            {
+                throw new Exception("Points needs to be same length");
+            }
+
+            var length = points0.Length;
+            for (var i = 0; i < length; i++)
+            {
+                var p00 = points0[i + 0];
+                var p01 = points0[(i + 1) % length];
+                var p10 = points1[i + 0];
+                var p11 = points1[(i + 1) % length];
+
+                AddQuad(p00, p10, p11, p01, flip);
+            }
+        }
+
+        public void AddCircle(Vector3[] points, Vector3 center, bool flip = false)
+        {
+            for (var i = 0; i < points.Length; i++)
+            {
+                var p0 = points[i + 0];
+                var p1 = points[(i + 1) % points.Length];
+                AddTriangle(p0, center, p1, flip);
+            }
+        }
+
+        public Mesh GetMesh()
+        {
+            var mesh = new Mesh()
+            {
+                vertices = vertices.ToArray(),
+                triangles = triangles.ToArray()
+            };
+            mesh.RecalculateBounds();
+            return mesh;
+        }
+    }
+}

Scripts/Util/MeshBuilder.cs

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+Shader "Unlit/Vertex Color"
+{
+    SubShader
+    {
+        Pass
+        {
+            CGPROGRAM
+            #pragma vertex vert
+            #pragma fragment frag
+
+            struct appdata
+            {
+                float4 vertex : POSITION;
+                float4 color : COLOR;
+            };
+
+            struct v2f
+            {
+                float4 vertex : SV_POSITION;
+                float4 color : COLOR;
+            };
+
+            v2f vert (appdata v)
+            {
+                v2f o;
+                o.vertex = UnityObjectToClipPos(v.vertex);
+                o.color = v.color;
+                return o;
+            }
+
+            fixed4 frag (v2f i) : SV_Target
+            {
+                return i.color;
+            }
+            ENDCG
+        }
+    }
+}