CreateCone

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Author: Wolfram Kresse

Description

This editor script creates a cone with the specified tessellation (=number of vertices), top radius, bottom radius, and length. With top radius == bottom radius, the result is a cylinder. With none of the radii == 0, the result is a truncated cone. So far the resulting cone has no end caps, but you can create caps on your own by using a cone with one radius==0 and length==0.

The resulting mesh will be added as an asset to Assets/Editor, so it can be used in prefabs etc.

Note it is inevitable that a true cone (one of the radii == 0) cannot be rendered completely smooth, and will show facetting artifacts.

Usage

Place this script as "CreateCone.cs" in YourProject/Assets/Editor and a menu item will automatically appear in the "GameObject/Create Other" menu after it is compiled.

Num Vertices is the number of vertices each end will have.
Radius Top is the radius at the top. The center point will be located at (0/0/0).
Radius Bottom is the radius at the bottom. The center point will be located at (0/0/Length).
Length is the number of world units long the plane will be (+Z direction).
Opening Angle If this is >0, the top radius is set to 0, and the bottom radius is computed depending on the length, so that the given opening angle is created.
Outside defines whether the outside is visible (default).
Inside defines whether the inside is visible. Set both outside and inside to create a double-sided primitive.
Add Collider creates a matching mesh collider for the cone if checked.


C# - CreateCone.cs

using UnityEngine;
using UnityEditor;
using System.Collections;
 
// an Editor method to create a cone primitive (so far no end caps)
// the top center is placed at (0/0/0)
// the bottom center is placed at (0/0/length)
// if either one of the radii is 0, the result will be a cone, otherwise a truncated cone
// note you will get inevitable breaks in the smooth shading at cone tips
// note the resulting mesh will be created as an asset in Assets/Editor
// Author: Wolfram Kresse
public class CreateCone : ScriptableWizard {
 
	public int numVertices = 10;
	public float radiusTop = 0f;
	public float radiusBottom = 1f;
	public float length = 1f;
	public float openingAngle = 0f; // if >0, create a cone with this angle by setting radiusTop to 0, and adjust radiusBottom according to length;
	public bool outside = true;
	public bool inside = false;
	public bool addCollider = false;
 
    [MenuItem ("GameObject/Create Other/Cone")]
    static void CreateWizard()
    {
        ScriptableWizard.DisplayWizard("Create Cone", typeof(CreateCone));
    }
 
	void OnWizardCreate(){
		GameObject newCone=new GameObject("Cone");
		if(openingAngle>0&&openingAngle<180){
			radiusTop=0;
			radiusBottom=length*Mathf.Tan(openingAngle*Mathf.Deg2Rad/2);
		}
		string meshName = newCone.name + numVertices + "v" + radiusTop + "t" + radiusBottom + "b" + length + "l" + length + (outside?"o":"") + (inside?"i":"");
		string meshPrefabPath = "Assets/Editor/" + meshName + ".asset";
		Mesh mesh = (Mesh)AssetDatabase.LoadAssetAtPath(meshPrefabPath, typeof(Mesh));
		if(mesh==null){
			mesh=new Mesh();
			mesh.name=meshName;
			// can't access Camera.current
			//newCone.transform.position = Camera.current.transform.position + Camera.current.transform.forward * 5.0f;
			int multiplier=(outside?1:0)+(inside?1:0);
			int offset=(outside&&inside?2*numVertices:0);
			Vector3[] vertices=new Vector3[2*multiplier*numVertices]; // 0..n-1: top, n..2n-1: bottom
			Vector3[] normals=new Vector3[2*multiplier*numVertices];
			Vector2[] uvs=new Vector2[2*multiplier*numVertices];
			int[] tris;
			float slope=Mathf.Atan((radiusBottom-radiusTop)/length); // (rad difference)/height
			float slopeSin=Mathf.Sin(slope);
			float slopeCos=Mathf.Cos(slope);
			int i;
 
			for(i=0;i<numVertices;i++){
				float angle=2*Mathf.PI*i/numVertices;
				float angleSin=Mathf.Sin(angle);
				float angleCos=Mathf.Cos(angle);
				float angleHalf=2*Mathf.PI*(i+0.5f)/numVertices; // for degenerated normals at cone tips
				float angleHalfSin=Mathf.Sin(angleHalf);
				float angleHalfCos=Mathf.Cos(angleHalf);
 
				vertices[i]=new Vector3(radiusTop*angleCos,radiusTop*angleSin,0);
				vertices[i+numVertices]=new Vector3(radiusBottom*angleCos,radiusBottom*angleSin,length);
 
				if(radiusTop==0)
					normals[i]=new Vector3(angleHalfCos*slopeCos,angleHalfSin*slopeCos,-slopeSin);
				else
					normals[i]=new Vector3(angleCos*slopeCos,angleSin*slopeCos,-slopeSin);
				if(radiusBottom==0)
					normals[i+numVertices]=new Vector3(angleHalfCos*slopeCos,angleHalfSin*slopeCos,-slopeSin);
				else
					normals[i+numVertices]=new Vector3(angleCos*slopeCos,angleSin*slopeCos,-slopeSin);
 
				uvs[i]=new Vector2(1.0f*i/numVertices,1);
				uvs[i+numVertices]=new Vector2(1.0f*i/numVertices,0);
 
				if(outside&&inside){
					// vertices and uvs are identical on inside and outside, so just copy
					vertices[i+2*numVertices]=vertices[i];
					vertices[i+3*numVertices]=vertices[i+numVertices];
					uvs[i+2*numVertices]=uvs[i];
					uvs[i+3*numVertices]=uvs[i+numVertices];
				}
				if(inside){
					// invert normals
					normals[i+offset]=-normals[i];
					normals[i+numVertices+offset]=-normals[i+numVertices];
				}
			}
			mesh.vertices = vertices;
			mesh.normals = normals;		
			mesh.uv = uvs;
 
			// create triangles
			// here we need to take care of point order, depending on inside and outside
			int cnt=0;
			if(radiusTop==0){
				// top cone
				tris=new int[numVertices*3*multiplier];
				if(outside)
					for(i=0;i<numVertices;i++){
						tris[cnt++]=i+numVertices;
						tris[cnt++]=i;
						if(i==numVertices-1)
							tris[cnt++]=numVertices;
						else
							tris[cnt++]=i+1+numVertices;
					}
				if(inside)
					for(i=offset;i<numVertices+offset;i++){
						tris[cnt++]=i;
						tris[cnt++]=i+numVertices;
						if(i==numVertices-1+offset)
							tris[cnt++]=numVertices+offset;
						else
							tris[cnt++]=i+1+numVertices;
					}
			}else if(radiusBottom==0){
				// bottom cone
				tris=new int[numVertices*3*multiplier];
				if(outside)
					for(i=0;i<numVertices;i++){
						tris[cnt++]=i;
						if(i==numVertices-1)
							tris[cnt++]=0;
						else
							tris[cnt++]=i+1;
						tris[cnt++]=i+numVertices;
					}
				if(inside)
					for(i=offset;i<numVertices+offset;i++){
						if(i==numVertices-1+offset)
							tris[cnt++]=offset;
						else
							tris[cnt++]=i+1;
						tris[cnt++]=i;
						tris[cnt++]=i+numVertices;
					}
			}else{
				// truncated cone
				tris=new int[numVertices*6*multiplier];
				if(outside)
					for(i=0;i<numVertices;i++){
						int ip1=i+1;
						if(ip1==numVertices)
							ip1=0;
 
						tris[cnt++]=i;
						tris[cnt++]=ip1;
						tris[cnt++]=i+numVertices;
 
						tris[cnt++]=ip1+numVertices;
						tris[cnt++]=i+numVertices;
						tris[cnt++]=ip1;
					}
				if(inside)
					for(i=offset;i<numVertices+offset;i++){
						int ip1=i+1;
						if(ip1==numVertices+offset)
							ip1=offset;
 
						tris[cnt++]=ip1;
						tris[cnt++]=i;
						tris[cnt++]=i+numVertices;
 
						tris[cnt++]=i+numVertices;
						tris[cnt++]=ip1+numVertices;
						tris[cnt++]=ip1;
					}
			}
			mesh.triangles = tris;		
			AssetDatabase.CreateAsset(mesh, meshPrefabPath);
			AssetDatabase.SaveAssets();
		}
 
		MeshFilter mf=newCone.AddComponent<MeshFilter>();
		mf.mesh = mesh;
 
		newCone.AddComponent<MeshRenderer>();
 
		if(addCollider){
			MeshCollider mc=newCone.AddComponent<MeshCollider>();
			mc.sharedMesh=mf.sharedMesh;
		}
 
        Selection.activeObject = newCone;
	}
}
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