一、介绍贝塞尔曲线
这里有不明白的可以去看 贝塞尔曲线 这篇文章。
二、Unity中贝塞尔曲线工具介绍
1.创建一个空物体挂在上BezierSpline.cs脚本组件
2.由上图可知刚创建出来的有两个点和两个手柄组成
3.我们可修改其坐标看下效果
4.这样我们就可以获得这两个点之间的指定数量的点来作为某个物体的运动轨迹
5.增加点
三、脚本构成如下
此工具总共三个脚本构成
1.放在Editor文件夹下的BezierSplineInspector.cs
using UnityEditor;
using UnityEngine;
[CustomEditor(typeof(BezierSpline))]
public class BezierSplineInspector : Editor
{
private const int stepsPerCurve = 10;
private const float directionScale = 0.5f;
private const float handleSize = 0.04f;
private const float pickSize = 0.06f;
private static Color[] modeColors = {
Color.white,
Color.yellow,
Color.cyan
};
private BezierSpline spline;
private Transform handleTransform;
private Quaternion handleRotation;
private int selectedIndex = -1;
public override void OnInspectorGUI()
{
spline = target as BezierSpline;
EditorGUI.BeginChangeCheck();
bool loop = EditorGUILayout.Toggle("Loop", spline.Loop);
if (EditorGUI.EndChangeCheck())
{
Undo.RecordObject(spline, "Toggle Loop");
EditorUtility.SetDirty(spline);
spline.Loop = loop;
}
if (selectedIndex >= 0 && selectedIndex < spline.ControlPointCount)
{
DrawSelectedPointInspector();
}
if (GUILayout.Button("Add Curve"))
{
Undo.RecordObject(spline, "Add Curve");
spline.AddCurve();
EditorUtility.SetDirty(spline);
}
}
private void DrawSelectedPointInspector()
{
GUILayout.Label("Selected Point");
EditorGUI.BeginChangeCheck();
Vector3 point = EditorGUILayout.Vector3Field("Position", spline.GetControlPoint(selectedIndex));
if (EditorGUI.EndChangeCheck())
{
Undo.RecordObject(spline, "Move Point");
EditorUtility.SetDirty(spline);
spline.SetControlPoint(selectedIndex, point);
}
EditorGUI.BeginChangeCheck();
BezierControlPointMode mode = (BezierControlPointMode)EditorGUILayout.EnumPopup("Mode", spline.GetControlPointMode(selectedIndex));
if (EditorGUI.EndChangeCheck())
{
Undo.RecordObject(spline, "Change Point Mode");
spline.SetControlPointMode(selectedIndex, mode);
EditorUtility.SetDirty(spline);
}
}
private void OnSceneGUI()
{
spline = target as BezierSpline;
handleTransform = spline.transform;
handleRotation = Tools.pivotRotation == PivotRotation.Local ?
handleTransform.rotation : Quaternion.identity;
Vector3 p0 = ShowPoint(0);
for (int i = 1; i < spline.ControlPointCount; i += 3)
{
Vector3 p1 = ShowPoint(i);
Vector3 p2 = ShowPoint(i + 1);
Vector3 p3 = ShowPoint(i + 2);
Handles.color = Color.gray;
Handles.DrawLine(p0, p1);
Handles.DrawLine(p2, p3);
Handles.DrawBezier(p0, p3, p1, p2, Color.white, null, 2f);
p0 = p3;
}
ShowDirections();
}
private void ShowDirections()
{
Handles.color = Color.green;
Vector3 point = spline.GetPoint(0f);
Handles.DrawLine(point, point + spline.GetDirection(0f) * directionScale);
int steps = stepsPerCurve * spline.CurveCount;
for (int i = 1; i <= steps; i++)
{
point = spline.GetPoint(i / (float)steps);
Handles.DrawLine(point, point + spline.GetDirection(i / (float)steps) * directionScale);
}
}
private Vector3 ShowPoint(int index)
{
Vector3 point = handleTransform.TransformPoint(spline.GetControlPoint(index));
float size = HandleUtility.GetHandleSize(point);
if (index == 0)
{
size *= 2f;
}
Handles.color = modeColors[(int)spline.GetControlPointMode(index)];
if (Handles.Button(point, handleRotation, size * handleSize, size * pickSize, Handles.DotCap))
{
selectedIndex = index;
Repaint();
}
if (selectedIndex == index)
{
EditorGUI.BeginChangeCheck();
point = Handles.DoPositionHandle(point, handleRotation);
if (EditorGUI.EndChangeCheck())
{
Undo.RecordObject(spline, "Move Point");
EditorUtility.SetDirty(spline);
spline.SetControlPoint(index, handleTransform.InverseTransformPoint(point));
}
}
return point;
}
}
2.Bezier.cs
using UnityEngine;
public static class Bezier
{
public static Vector3 GetPoint(Vector3 p0, Vector3 p1, Vector3 p2, float t)
{
t = Mathf.Clamp01(t);
float oneMinusT = 1f - t;
return
oneMinusT * oneMinusT * p0 +
2f * oneMinusT * t * p1 +
t * t * p2;
}
public static Vector3 GetFirstDerivative(Vector3 p0, Vector3 p1, Vector3 p2, float t)
{
return
2f * (1f - t) * (p1 - p0) +
2f * t * (p2 - p1);
}
public static Vector3 GetPoint(Vector3 p0, Vector3 p1, Vector3 p2, Vector3 p3, float t)
{
t = Mathf.Clamp01(t);
float OneMinusT = 1f - t;
return
OneMinusT * OneMinusT * OneMinusT * p0 +
3f * OneMinusT * OneMinusT * t * p1 +
3f * OneMinusT * t * t * p2 +
t * t * t * p3;
}
public static Vector3 GetFirstDerivative(Vector3 p0, Vector3 p1, Vector3 p2, Vector3 p3, float t)
{
t = Mathf.Clamp01(t);
float oneMinusT = 1f - t;
return
3f * oneMinusT * oneMinusT * (p1 - p0) +
6f * oneMinusT * t * (p2 - p1) +
3f * t * t * (p3 - p2);
}
}
3.BezierSpline.cs
using UnityEngine;
using System;
public class BezierSpline : MonoBehaviour
{
[SerializeField]
public Vector3[] points;
[SerializeField]
private BezierControlPointMode[] modes;
[SerializeField]
private bool loop;
public bool Loop
{
get
{
return loop;
}
set
{
loop = value;
if (value == true)
{
modes[modes.Length - 1] = modes[0];
SetControlPoint(0, points[0]);
}
}
}
public int ControlPointCount
{
get
{
return points.Length;
}
}
public Vector3 GetControlPoint(int index)
{
return points[index];
}
public void SetControlPoint(int index, Vector3 point)
{
if (index % 3 == 0)
{
Vector3 delta = point - points[index];
if (loop)
{
if (index == 0)
{
points[1] += delta;
points[points.Length - 2] += delta;
points[points.Length - 1] = point;
}
else if (index == points.Length - 1)
{
points[0] = point;
points[1] += delta;
points[index - 1] += delta;
}
else
{
points[index - 1] += delta;
points[index + 1] += delta;
}
}
else
{
if (index > 0)
{
points[index - 1] += delta;
}
if (index + 1 < points.Length)
{
points[index + 1] += delta;
}
}
}
points[index] = point;
EnforceMode(index);
}
public BezierControlPointMode GetControlPointMode(int index)
{
return modes[(index + 1) / 3];
}
public void SetControlPointMode(int index, BezierControlPointMode mode)
{
int modeIndex = (index + 1) / 3;
modes[modeIndex] = mode;
if (loop)
{
if (modeIndex == 0)
{
modes[modes.Length - 1] = mode;
}
else if (modeIndex == modes.Length - 1)
{
modes[0] = mode;
}
}
EnforceMode(index);
}
private void EnforceMode(int index)
{
int modeIndex = (index + 1) / 3;
BezierControlPointMode mode = modes[modeIndex];
if (mode == BezierControlPointMode.Free || !loop && (modeIndex == 0 || modeIndex == modes.Length - 1))
{
return;
}
int middleIndex = modeIndex * 3;
int fixedIndex, enforcedIndex;
if (index <= middleIndex)
{
fixedIndex = middleIndex - 1;
if (fixedIndex < 0)
{
fixedIndex = points.Length - 2;
}
enforcedIndex = middleIndex + 1;
if (enforcedIndex >= points.Length)
{
enforcedIndex = 1;
}
}
else
{
fixedIndex = middleIndex + 1;
if (fixedIndex >= points.Length)
{
fixedIndex = 1;
}
enforcedIndex = middleIndex - 1;
if (enforcedIndex < 0)
{
enforcedIndex = points.Length - 2;
}
}
Vector3 middle = points[middleIndex];
Vector3 enforcedTangent = middle - points[fixedIndex];
if (mode == BezierControlPointMode.Aligned)
{
enforcedTangent = enforcedTangent.normalized * Vector3.Distance(middle, points[enforcedIndex]);
}
points[enforcedIndex] = middle + enforcedTangent;
}
public int CurveCount
{
get
{
return (points.Length - 1) / 3;
}
}
public Vector3 GetPoint(float t)
{
int i;
if (t >= 1f)
{
t = 1f;
i = points.Length - 4;
}
else
{
t = Mathf.Clamp01(t) * CurveCount;
i = (int)t;
t -= i;
i *= 3;
}
return transform.TransformPoint(Bezier.GetPoint(points[i], points[i + 1], points[i + 2], points[i + 3], t));
}
public Vector3 GetVelocity(float t)
{
int i;
if (t >= 1f)
{
t = 1f;
i = points.Length - 4;
}
else
{
t = Mathf.Clamp01(t) * CurveCount;
i = (int)t;
t -= i;
i *= 3;
}
return transform.TransformPoint(Bezier.GetFirstDerivative(points[i], points[i + 1], points[i + 2], points[i + 3], t)) - transform.position;
}
public Vector3 GetDirection(float t)
{
return GetVelocity(t).normalized;
}
public void AddCurve()
{
Vector3 point = points[points.Length - 1];
Array.Resize(ref points, points.Length + 3);
point.x += 1f;
points[points.Length - 3] = point;
point.x += 1f;
points[points.Length - 2] = point;
point.x += 1f;
points[points.Length - 1] = point;
Array.Resize(ref modes, modes.Length + 1);
modes[modes.Length - 1] = modes[modes.Length - 2];
EnforceMode(points.Length - 4);
if (loop)
{
points[points.Length - 1] = points[0];
modes[modes.Length - 1] = modes[0];
EnforceMode(0);
}
}
public void Reset()
{
points = new Vector3[] {
new Vector3(1f, 0f, 0f),
new Vector3(2f, 0f, 0f),
new Vector3(3f, 0f, 0f),
new Vector3(4f, 0f, 0f)
};
modes = new BezierControlPointMode[] {
BezierControlPointMode.Free,
BezierControlPointMode.Free
};
}
}
public enum BezierControlPointMode
{
Free,
Aligned,
Mirrored
}