我想实现我可以细分具有给定距离的贝塞尔曲线。现在它可以工作,如果贝塞尔是一条直线,但如果我改变一个控制点(B&C),使贝塞尔得到弯曲,计算点之间的差距就不再像给定的距离!
我通过网络浏览,但没有遇到类似的问题。
float t = Distance between subdividedParts / bezier length;
//A,B,C,D = ControllPoints of Bezier
GetPoint(A,B,C,D,t);
//GetPoint equation:
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;
}
我现在已经设法得到非常准确的方法来分割Bezier并获得Positions =>但是它的性能消耗正在增加,因为它更准确。所以这可以在这段代码中得到改进:
//if accuracy is 0.001 = good performance | if 0.000001 laggy performance
public Vector3[] GetPoints (float gap,float accuracy){
SimpsonVec sv = SV_Setup(0);
Vector3 last_spawn = Bezier.GetPoint(sv.A,sv.B,sv.C,sv.D,0);
List<Vector3> allPoints = new List<Vector3>();
allPoints.Add(last_spawn);
for(float t = accuracy;t <= 1.0f; t +=accuracy){
Vector3 trial = Bezier.GetPoint(sv.A,sv.B,sv.C,sv.D,t);
if(Vector3.Distance(trial,last_spawn) >= gap){
last_spawn = trial;
allPoints.Add(trial);
}
}
return allPoints.ToArray();
}
为了更好的表现,我现在做了这个:
Vector3 []数组输出的代码
public Vector3[] GetAllPoints(float gap,float acc){
SimpsonVector = SV_SETUP_ALL();
BezierPoints bp = new BezierPoints();
bp.bp_vector3 = new List<Vector3>();
bp.bp_lastSpawn = new List<Vector3>();
for(int i = 0; i<points.Length / 3;i++){
Vector3 ls = new Vector3();
if(i == 0){
ls = Bezier.GetPoint(SimpsonVector[0].A,SimpsonVector[0].B,SimpsonVector[0].C,SimpsonVector[0].D,0);
}if (i > 0){
ls = bp.bp_lastSpawn[i-1];
}
BezierPoints bp_temp = GetSegmentPoints(gap,acc,i,ls);
bp.bp_lastSpawn.Add(bp_temp.bp_lastSpawn[0]);
bp.bp_vector3.AddRange(bp_temp.bp_vector3);
SimpsonVector_TEMP = SimpsonVector;
}
return bp.bp_vector3.ToArray();
}
BezierPoints GetSegmentPoints (float gap,float acc,int index, Vector3 ls)
{
SimpsonVec sv = SimpsonVector[index];
Vector3 last_spawn = ls;
BezierPoints bp = new BezierPoints();
bp.bp_vector3 = new List<Vector3>();
bp.bp_lastSpawn = new List<Vector3>();
float step = 0.1f;
float t = step;
float lastT = new float();
while (t >= 0 && t <= 1f)
{
while (t < 1f && Vector3.Distance(Bezier.GetPoint(sv.A,sv.B,sv.C,sv.D,t), last_spawn) < gap){
t += step;}
step /= acc;
while (t > lastT && Vector3.Distance(Bezier.GetPoint(sv.A,sv.B,sv.C,sv.D,t), last_spawn) > gap){
t -= step;}
step /= acc;
if (t > 1f || t < lastT){
break;}
if(step < 0.000001f){
last_spawn = Bezier.GetPoint(sv.A,sv.B,sv.C,sv.D,t);
bp.bp_vector3.Add(last_spawn + transform.position);
lastT = t;
step = 0.1f;
}
}
bp.bp_lastSpawn.Add(last_spawn);
return bp;
}
结构:
public struct SimpsonVec{
[SerializeField] public Vector3 A;
[SerializeField] public Vector3 B;
[SerializeField] public Vector3 C;
[SerializeField] public Vector3 D;
}
public struct BezierPoints
{
[SerializeField] public List<Vector3> bp_vector3;
[SerializeField] public List<Vector3> bp_lastSpawn;
}
帮手方法:
public SimpsonVec SV_Setup(int index){
SimpsonVec sv;
sv.A = points[index];
sv.B = points[index+1];
sv.C = points[index+2];
sv.D = points[index+3];
return sv;
}
public SimpsonVec[] SV_SETUP_ALL(){
SimpsonVec[] sv = new SimpsonVec[points.Length / 3];
for(int i = 0; i<points.Length / 3;i++){
sv[i] = SV_Setup(i*3);
}
return sv;
}
public 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;
}
您无论如何都需要绘制曲线,因此请保持曲线的查找表并预先计算每个条目的距离,或者通过选择t
值,计算距离,然后移动t
值的一半来二进制搜索您的胜利之路/如果你关闭了,请重复,直到你达到所需的精度。而且因为二进制搜索是疯狂有效的,所以你在那里尝试的次数可以忽略不计。
请参阅https://pomax.github.io/bezierinfo/#tracing的基本原理,https://pomax.github.io/bezierinfo/#arclength用于计算曲线的长度(https://pomax.github.io/bezierinfo/#splitting是获取确定曲线长度t
所需的值的明显部分),以及“所有https://pomax.github.io/bezierinfo获取更多信息”,真的。