unity3d 图形吧 之 场景中画圆

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孙广东：2015-2-6/2:28  转载请注明出处：http://blog.csdn.net/u010019717

更全的内容请看我的游戏蛮牛地址：http://www.unitymanual.com/space-uid-18602.html

先看一下效果：

区别就是一个2d一个3d.

2d就不介绍了，相对简单一些，对于3d的内容，我们先来看一看数学中的一个题和答案，这样就很容易理解程序了。

这样就好办了！    直接看下面几个脚本吧。

using UnityEngine;
using System.Collections;
using SunGuangDong.Math;

[ExecuteInEditMode]
public class DrawCircleMono : MonoBehaviour {
	private Vector3 m_Normal ;

	// Use this for initialization
	void Start () {
		m_Normal = new Vector3 (0, 1, 0);
	}

	void OnDrawGizmos()
	{
		Circle2d circle2 = new Circle2d(transform.position, 5);
		DrawCircle(ref circle2, Color.red);

		Vector3 center = new Vector3 (transform.position.x, transform.position.y + 0.2f, transform.position.z);
		Circle3d circle3 = new Circle3d(ref center,ref m_Normal, 5);
		DrawCircle (circle3, Color.red, 40);
	}

	protected void DrawCircle(ref Circle2d circle, Color color)
	{
		int count = 40;
		float delta = 2f * Mathf.PI / count;
		Vector3 prev = circle.Eval(0);

		Color tempColor = Gizmos.color;
		Gizmos.color = color;

		for (int i = 1; i <= count; ++i)
		{
			Vector3 curr = circle.Eval(i * delta);
			Gizmos.DrawLine(prev, curr);
			prev = curr;
		}

		Gizmos.color = tempColor;
	}

	protected void DrawCircle(Vector2 center, float radius, Color color)
	{
		Circle2d circle = new Circle2d(ref center, radius);
		int count = 40;
		float delta = 2f * Mathf.PI / count;
		Vector3 prev = circle.Eval(0);

		Color tempColor = Gizmos.color;
		Gizmos.color = color;

		for (int i = 1; i <= count; ++i)
		{
			Vector3 curr = circle.Eval(i * delta);
			Gizmos.DrawLine(prev, curr);
			prev = curr;
		}

		Gizmos.color = tempColor;
	}

	protected void DrawCircle(Circle3d circle, Color color, int count = 20)
	{
		float delta = 2f * Mathf.PI / count;
		Vector3 prev = circle.Eval(0);

		Color tempColor = Gizmos.color;
		Gizmos.color = color;

		for (int i = 1; i <= count; ++i)
		{
			Vector3 curr = circle.Eval(i * delta);
			Gizmos.DrawLine(prev, curr);
			prev = curr;
		}

		Gizmos.color = tempColor;
	}
}

上面这个脚本在 挂到场景中的任意对象上，如Cube

namespace SunGuangDong.Math
{
    using System;
    using System.Collections.Generic;
    using System.Runtime.InteropServices;
    using UnityEngine;

    [StructLayout(LayoutKind.Sequential)]
    public struct Circle2d
    {
        public Vector2 Center;
        public float Radius;
        public Circle2d(ref Vector2 center, float radius)
        {
            this.Center = center;
            this.Radius = radius;
        }

        public Circle2d(Vector2 center, float radius)
        {
            this.Center = center;
            this.Radius = radius;
        }

        public float CalcPerimeter()
        {
            return (6.283185f * this.Radius);
        }

        public float CalcArea()
        {
            return ((3.141593f * this.Radius) * this.Radius);
        }

        public Vector2 Eval(float t)
        {
            return new Vector2(this.Center.x + (this.Radius * Mathf.Cos(t)), this.Center.y + (this.Radius * Mathf.Sin(t)));
        }

        public Vector2 Eval(float t, float radius)
        {
            return new Vector2(this.Center.x + (radius * Mathf.Cos(t)), this.Center.y + (radius * Mathf.Sin(t)));
        }
        public bool Contains(ref Vector2 point)
        {
            Vector2 vector = point - this.Center;
			return (vector.magnitude <= (this.Radius * this.Radius));
        }

        public bool Contains(Vector2 point)
        {
            Vector2 vector = point - this.Center;
			return (vector.magnitude <= (this.Radius * this.Radius));
        }

        public void Include(ref Circle2d circle)
        {
            Vector2 vector = circle.Center - this.Center;
			float num = vector.magnitude;
            float num2 = circle.Radius - this.Radius;
            float num3 = num2 * num2;
            if (num3 >= num)
            {
                if (num2 >= 0f)
                {
                    this = circle;
                }
            }
            else
            {
                float num4 = Mathf.Sqrt(num);
                if (num4 > 1E-05f)
                {
                    float num5 = (num4 + num2) / (2f * num4);
                    this.Center += (Vector2) (num5 * vector);
                }
                this.Radius = 0.5f * ((num4 + this.Radius) + circle.Radius);
            }
        }

        public void Include(Circle2d circle)
        {
            this.Include(ref circle);
        }
    }
}

namespace SunGuangDong.Math
{
    using System;
    using System.Runtime.InteropServices;
    using UnityEngine;

    [StructLayout(LayoutKind.Sequential)]
    public struct Circle3d
    {
        public Vector3 Center;
        public Vector3 Axis0;
        public Vector3 Axis1;
        public Vector3 Normal;
        public float Radius;

        public Circle3d(ref Vector3 center, ref Vector3 normal, float radius)
        {
            this.Center = center;
            this.Normal = normal;
            Vector3ex.CreateOrthonormalBasis(out this.Axis0, out this.Axis1, ref this.Normal);
            this.Radius = radius;
        }

        public Circle3d(Vector3 center, Vector3 normal, float radius)
        {
            this.Center = center;
            this.Normal = normal;
            Vector3ex.CreateOrthonormalBasis(out this.Axis0, out this.Axis1, ref this.Normal);
            this.Radius = radius;
        }

        public float CalcPerimeter()
        {
            return (6.283185f * this.Radius);
        }

        public float CalcArea()
        {
            return ((3.141593f * this.Radius) * this.Radius);
        }

        public Vector3 Eval(float t)
        {
            return (this.Center + ((Vector3) (this.Radius * ((Mathf.Cos(t) * this.Axis0) + (Mathf.Sin(t) * this.Axis1)))));
        }

        public Vector3 Eval(float t, float radius)
        {
            return (this.Center + ((Vector3) (radius * ((Mathf.Cos(t) * this.Axis0) + (Mathf.Sin(t) * this.Axis1)))));
        }
    }
}

namespace SunGuangDong.Math
{
    using System;
    using System.Collections.Generic;
    using System.Runtime.CompilerServices;
    using System.Runtime.InteropServices;
    using UnityEngine;

    public static class Vector3ex
    {
        public static readonly Vector3 Zero = new Vector3(0f, 0f, 0f);

        public static void CreateOrthonormalBasis(out Vector3 u, out Vector3 v, ref Vector3 w)
        {
            if (Mathf.Abs(w.x) >= Mathf.Abs(w.y))
            {
                float num = Mathfex.InvSqrt((w.x * w.x) + (w.z * w.z));
                u.x = -w.z * num;
                u.y = 0f;
                u.z = w.x * num;
                v.x = w.y * u.z;
                v.y = (w.z * u.x) - (w.x * u.z);
                v.z = -w.y * u.x;
            }
            else
            {
                float num2 = Mathfex.InvSqrt((w.y * w.y) + (w.z * w.z));
                u.x = 0f;
                u.y = w.z * num2;
                u.z = -w.y * num2;
                v.x = (w.y * u.z) - (w.z * u.y);
                v.y = -w.x * u.z;
                v.z = w.x * u.y;
            }
        }
	}
}

namespace SunGuangDong.Math
{
    using System;
    using System.Runtime.InteropServices;
    using UnityEngine;

    public static class Mathfex
    {
        public const float Pi = 3.141593f;

        public static float InvSqrt(float value)
        {
            if (value != 0f)
            {
                return (1f / Mathf.Sqrt(value));
            }
            return 0f;
        }
    }
}

最后附上一些其他图片吧。