平衡三个参数，以便当其中一个参数发生变化时，数量不会改变

Question

我需要平衡三个变量，以便在向其中一个变量添加值时，其他变量按比例变化，从而使数量保持原始状态。例如，辐射 4 中的身体三角形。https://i.stack.imgur.com/0oNqT.jpg

我尝试了一些东西，但它不正确，实际上不起作用。
起初，我只是将缺失的数量添加到其他变量中，但没有比例。
其次，我试图通过比例来平衡：

public class Triangle()
{
    float a = 0.33f;
    float b = 0.33f;
    float c = 0.33f;
    static float sum = 0.99f;
    static float maxVal = 0.97f;
    void AddA(float value)  {
        if (a + value <= maxVal) {
            a += value;         
            float ratio1 = b/sum;
            float ratio2 = c/sum;
            // difference between needed sum and current
            float remainderSum = a+b+c-sum;
            // the excess part is proportional to b
            float rem1 = remainderSum*ratio1;
            // the excess part is proportional to c
            float rem2 = remainderSum*ratio2;
            // subtract excess
            b -= rem1;
            c -= rem2;
        }
    }
}

结果：

Add(0.5f); =>
  Sum: 1.1566666666666665
  ABC: 0.8300000000000001/0.16333333333333325/0.16333333333333325

但在结果总和不正确。

Answer 1

每次将一个变量增加一个变量时，您都希望减少其他两个变量。如果将它们分别减少一半，则所有三个变量的总和保持不变。

伪代码：

total = 1; //you could change this to anything
x = total/3;
y = total/3;
z = total/3;
def increaseX(amount) {
    x = x + amount;
    y = y - amount/2;
    z = z - amount/2;
}
def increaseY(amount) {
    y = y + amount;
    x = x - amount/2;
    z = z - amount/2;
}
def increaseZ(amount) {
    z = z + amount;
    x = x - amount/2;
    y = y - amount/2;
}

Answer 2

class Param3:
    MAX = 300
    a = 100
    b = 100
    c = 100
    
    def __init__(self, a, b):
        self.a = a
        self.b = b
        self.c = MAX-a-b
        
    def add_A(val):
        # Limitation
        if a+val > MAX:
            val = MAX-a
            print("A > MAX, must be <=")
        elif a+val < 0:
            val = -a
            print("A < 0, must be >=")
        
        a += val
        var coef = b/(b+c)
        b -= val*coef
        c = MAX - a - b