JAVA四元数和欧拉角转换，向量四元数旋转。Quaternion，EulerAngles类

JAVA 四元数和欧拉角转换，旋转。Quaternion，EulerAngles类

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欧拉角类：

public class EulerAngles {
    
    
    public float pitch;
    public float yaw;
    public float roll;

    public EulerAngles(float pitch, float yaw, float roll) {
    
    
        this.pitch = pitch;
        this.yaw = yaw;
        this.roll = roll;
    }

    public EulerAngles(float w, float x, float y, float z) {
    
    
        // roll (x-axis rotation)
        float sinr_cosp = 2 * (w * x + y * z);
        float cosr_cosp = 1 - 2 * (x * x + y * y);
        this.roll = (float) Math.atan2(sinr_cosp, cosr_cosp);

        // pitch (y-axis rotation)
        float sinp = 2 * (w * y - z * x);
        if (Math.abs(sinp) >= 1) {
    
    
            this.pitch = Math.copySign(1.57075f, sinp); // use 90 degrees if out of range
        } else {
    
    
            this.pitch = (float) Math.asin(sinp);
        }

        // yaw (z-axis rotation)
        float siny_cosp = 2 * (w * z + x * y);
        float cosy_cosp = 1 - 2 * (y * y + z * z);
        this.yaw = (float) Math.atan2(siny_cosp, cosy_cosp);
    }

    public Quaternion ToQuaternion() {
    
    
    	//欧拉角转四元数，角度减半是因为四元数旋转计算时需要旋转两次，具体原理请查看四元数原理
        float cy = (float) Math.cos(yaw * 0.5f);
        float sy = (float) Math.sin(yaw * 0.5f);
        float cp = (float) Math.cos(pitch * 0.5f);
        float sp = (float) Math.sin(pitch * 0.5f);
        float cr = (float) Math.cos(roll * 0.5f);
        float sr = (float) Math.sin(roll * 0.5f);
        Quaternion q = new Quaternion();
        q.w = cy * cp * cr + sy * sp * sr;
        q.x = cy * cp * sr - sy * sp * cr;
        q.y = sy * cp * sr + cy * sp * cr;
        q.z = sy * cp * cr - cy * sp * sr;
        return q;
    }
}

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四元数类：

public class Quaternion {
    
    
    public float w;
    public float x;
    public float y;
    public float z;

    public Quaternion() {
    
    
    }

    public Quaternion(float w,float x,float y,float z) {
    
    
        this.w = w;
        this.x = x;
        this.y = y;
        this.z = z;
    }

    //向量旋转
    static void VectorRotation(float[] vector,Quaternion q) {
    
    
        Quaternion qv = new Quaternion(0,vector[0],vector[1],vector[2]);
        //四元数旋转公式q0*qv*（q0逆）s
        qv = Quaternion.Multiplication(Quaternion.Multiplication(q, qv),q.Inverse());
        vector[0] = qv.x;
        vector[1] = qv.y;
        vector[2] = qv.z;
    }


    //返回欧拉角
    public EulerAngles ToEulerAngles() {
    
    
        // roll (x-axis rotation)
        return new EulerAngles(this.w,this.x,this.y,this.z);
    }

    //四元数相乘
    static Quaternion Multiplication(Quaternion q0, Quaternion q1) {
    
    
        Quaternion ret = new Quaternion();
        ret.w = q0.w * q1.w - q0.x * q1.x - q0.y * q1.y - q0.z * q1.z;
        ret.x = q0.w * q1.x + q0.x * q1.w + q0.y * q1.z - q0.z * q1.y;
        ret.y = q0.w * q1.y + q0.y * q1.w + q0.z * q1.x - q0.x * q1.z;
        ret.z = q0.w * q1.z + q0.z * q1.w + q0.x * q1.y - q0.y * q1.x;
        return ret;
    }

    //四元数求逆
    public Quaternion Inverse() {
    
    
        Quaternion ret;
        ret = this;
        ret.x *= -1;
        ret.y *= -1;
        ret.z *= -1;
        return ret;
    }
}