Unity draws smooth lines based on lineRenderer and Bezier curves

Table of contents

foreword

1. Call method

2. Code example

achieve effect

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foreword

In unity, it is now necessary to generate a closed, smooth curve based on the control points and draw it using linerenderer

1. Call method

The code is as follows (example): pass in a list of control points, and the lineRenderer component

DrawBezierCurve(posList, lineRender);

2. Code example

/// <summary> 
/// Generate the corresponding Bezier curve according to the control points 
/// </summary> 
/// <param name="positions"></param> 
/// <param name="lineRenderer "></param> 
private void DrawBezierCurve(List<Vector3> positions, LineRenderer lineRenderer) 
{ 
    if (positions.Count < 2) 
    { 
        return; 
    } 

    var partCount = 20; 
    
    lineRenderer.positionCount = 0; 
    lineRenderer.positionCount = (positions. Count - 1) * partCount ; 

    for (int i = 0; i < positions.Count - 1; i++) 
    { 
        Vector3 p0 = i == 0 ? positions[0] :positions[i - 1];
        Vector3 p1 = positions[i];
        Vector3 p2 = positions[i + 1];
        Vector3 p3 = i == positions.Count - 2 ? positions[positions.Count - 1] : positions[i + 2];
        
        for (int j = 0; j < partCount; j++)
        {
            var t = (float)j / partCount;

            Vector3 point = CalculateCatMullRomPoint(t, p0, p1, p2, p3);
            
            lineRenderer.SetPosition(i * partCount + j, point);
        }
    }
}

/// <summary>
/// 计算CatMullRomPoint
/// </summary>
/// <param name="t"></param>
/// <param name="p0"></param>
/// <param name="p1"></param>
/// <param name="p2"></param>
/// <param name="p3"></param>
/// <returns></returns>
private Vector3 CalculateCatMullRomPoint(float t, Vector3 p0, Vector3 p1, Vector3 p2, Vector3 p3)
{
    float t2 = t * t;
    float t3 = t2 * t;

    Vector3 point =
        0.5f * ((2f * p1) +
                (-p0 + p2) * t +
                (2f * p0 - 5f * p1 + 4f * p2 - p3) * t2 +
                (-p0 + 3f * p1 - 3f * p2 + p3) * t3);

    return point;
}

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achieve effect