pygame.math.Vector2 构造函数参数表示什么？

Question

I'm trying to figure out how to create a unit vector / normalized Vector2 instance given an angle (degrees). I encountered the following as I was reading pygame's documentation at https://www.pygame.org/docs/ref/math.html#pygame.math.Vector2 :

Vector2() -> Vector2
Vector2(int) -> Vector2
Vector2(float) -> Vector2
Vector2(Vector2) -> Vector2
Vector2(x, y) -> Vector2
Vector2((x, y)) -> Vector2

To my understanding, they generate the following vectors:

Vector2() -> (0, 0)
Vector2(Vector2) -> (Vector2.x, Vector2.y)
Vector2(x, y) -> (x, y)
Vector2((x, y)) -> (x, y)

But what do int and float parameter datatypes indicate? Also, please correct if I have misunderstood the above assumptions.

Moreover, can I instantiate a normalized Vector2 object given an angle or do I need to do some trigonometry with math library first?

Answer 1

I'm trying to figure out how to create a unit vector / normalized Vector2 instance given an angle

The length of a unit vector is 1, so the simplest way to create a unit vector with a given angle is:

v = pygame.math.Vector2(1, 0)
v.rotate_ip(angle)

Alternatively, you can create the vector with the trigonomentry functions sin and cos :

angle_radian = math.radians(angle_degree)
v = pygame.math.Vector2(math.cos(angle_radian), math.sin(angle_radian))

---

All vector constructors construct a vector with the specified scalars. The constructors with only one argument create a vector where the x and y components are equal.

You can easily find out yourself by using print :

print(pygame.math.Vector2())
print(pygame.math.Vector2(1))
print(pygame.math.Vector2(1.5))
print(pygame.math.Vector2(2, 3))
print(pygame.math.Vector2((2.5, 3.5)))

Output:

[0, 0]
[1, 1]
[1.5, 1.5]
[2, 3]
[2.5, 3.5]

int and float indicates that you can construct the vector with integral and floating point numbers, however this has no effect on the behavior of the object.