Add c# samples to Vector Math

This commit is contained in:
Kelly thomas
2018-04-05 20:05:58 +08:00
parent d355c2c7e0
commit 95584177a5

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@@ -63,10 +63,16 @@ coordinate notation. For example, in Godot the origin is the top-left
corner of the screen, so to place a 2D node named ``Node2D`` 400 pixels to the right and
300 pixels down, use the following code:
::
.. tabs::
.. code-tab:: gdscript GDScript
$Node2D.position = Vector2(400, 300)
.. code-tab:: csharp
var node2D = (Node2D) GetNode("Node2D");
node2D.Position = new Vector2(400, 300);
Godot supports both :ref:`Vector2 <class_Vector2>` and
:ref:`Vector3 <class_Vector3>` for 2D and 3D usage respectively. The same
mathematical rules discussed in this article apply for both types.
@@ -75,7 +81,8 @@ mathematical rules discussed in this article apply for both types.
The individual components of the vector can be accessed directly by name.
::
.. tabs::
.. code-tab:: gdscript GDScript
# create a vector with coordinates (2, 5)
var a = Vector2(2, 5)
@@ -84,14 +91,28 @@ The individual components of the vector can be accessed directly by name.
b.x = 3
b.y = 1
.. code-tab:: csharp
// create a vector with coordinates (2, 5)
var a = new Vector2(2, 5);
// create a vector and assign x and y manually
var b = new Vector2();
b.x = 3;
b.y = 1;
- Adding vectors
When adding or subtracting two vectors, the corresponding components are added:
::
.. tabs::
.. code-tab:: gdscript GDScript
var c = a + b # (2, 5) + (3, 1) = (5, 6)
.. code-tab:: csharp
var c = a + b; // (2, 5) + (3, 1) = (5, 6)
We can also see this visually by adding the second vector at the end of
the first:
@@ -106,11 +127,17 @@ Note that adding ``a + b`` gives the same result as ``b + a``.
A vector can be multiplied by a **scalar**:
::
.. tabs::
.. code-tab:: gdscript GDScript
var c = a * 2 # (2, 5) * 2 = (4, 10)
var d = b / 3 # (3, 6) / 3 = (1, 2)
.. code-tab:: csharp
var c = a * 2; // (2, 5) * 2 = (4, 10)
var d = b / 3; // (3, 6) / 3 = (1, 2)
.. image:: img/vector_mult1.png
.. note:: Multiplying a vector by a scalar does not change its direction,
@@ -158,20 +185,34 @@ Normalization
preserving its direction. This is done by dividing each of its components
by its magnitude:
::
.. tabs::
.. code-tab:: gdscript GDScript
var a = Vector2(2, 4)
var m = sqrt(a.x*a.x + a.y*a.y) # get magnitude "m" using the Pythagorean theorem
a.x /= m
a.y /= m
.. code-tab:: csharp
var a = new Vector2(2, 4);
var m = Mathf.Sqrt(a.x*a.x + a.y*a.y); // get magnitude "m" using the Pythagorean theorem
a.x /= m;
a.y /= m;
Because this is such a common operation, ``Vector2`` and ``Vector3`` provide
a method for normalizing:
::
.. tabs::
.. code-tab:: gdscript GDScript
a = a.normalized()
.. code-tab:: csharp
a = a.Normalized();
.. warning:: Because normalization involves dividing by the vector's length,
you cannot normalize a vector of length ``0``. Attempting to
do so will result in an error.
@@ -196,14 +237,28 @@ Godot, the :ref:`Vector2 <class_Vector2>` class has a ``bounce()`` method
to handle this. Here is a GDScript example of the diagram above using a
:ref:`KinematicBody2D <class_KinematicBody2D>`:
::
var collision = move_and_collide(velocity * delta) # object "collision" contains information about the collision
.. tabs::
.. code-tab:: gdscript GDScript
# object "collision" contains information about the collision
var collision = move_and_collide(velocity * delta)
if collision:
var reflect = collision.remainder.bounce(collision.normal)
velocity = velocity.bounce(collision.normal)
move_and_collide(reflect)
.. code-tab:: csharp
// KinematicCollision2D contains information about the collision
KinematicCollision2D collision = MoveAndCollide(_velocity * delta);
if (collision != null)
{
var reflect = collision.Remainder.Bounce(collision.Normal);
_velocity = _velocity.Bounce(collision.Normal);
MoveAndCollide(reflect);
}
Dot product
~~~~~~~~~~~
@@ -227,11 +282,17 @@ and
However, in most cases it is easiest to use the built-in method. Note that
the order of the two vectors does not matter:
::
.. tabs::
.. code-tab:: gdscript GDScript
var c = a.dot(b)
var d = b.dot(a) # these are equivalent
.. code-tab:: csharp
float c = a.Dot(b);
float d = b.Dot(a); // these are equivalent
The dot product is most useful when used with unit vectors, making the
first formula reduce to just ``cosθ``. This means we can use the dot
product to tell us something about the angle between two vectors:
@@ -259,12 +320,21 @@ the player.
In GDScript it would look like this:
::
.. tabs::
.. code-tab:: gdscript GDScript
var AP = (P - A).normalized()
if AP.dot(fA) > 0:
print("A sees P!")
.. code-tab:: csharp
var AP = (P - A).Normalized();
if (AP.Dot(fA) > 0)
{
GD.Print("A sees P!");
}
Cross product
~~~~~~~~~~~~~
@@ -281,19 +351,34 @@ If two vectors are parallel, the result of their cross product will be null vect
The cross product is calculated like this:
::
.. tabs::
.. code-tab:: gdscript GDScript
var c = Vector3()
c.x = (a.y * b.z) - (a.z * b.y)
c.y = (a.z * b.x) - (a.x * b.z)
c.z = (a.x * b.y) - (a.y * b.x)
.. code-tab:: csharp
var c = new Vector3();
c.x = (a.y * b.z) - (a.z * b.y);
c.y = (a.z * b.x) - (a.x * b.z);
c.z = (a.x * b.y) - (a.y * b.x);
In GDScript, you can use the built-in method:
::
.. tabs::
.. code-tab:: gdscript GDScript
var c = a.cross(b)
.. code-tab:: csharp
var c = a.Cross(b);
.. note:: In the cross product, order matters. ``a.cross(b)`` does not
give the same result as ``b.cross(a)``. The resulting vectors
point in **opposite** directions.
@@ -308,7 +393,8 @@ subtraction to find two edges ``AB`` and ``AC``. Using the cross product,
Here is a function to calculate a triangle's normal in GDScript:
::
.. tabs::
.. code-tab:: gdscript GDScript
func get_triangle_normal(a, b, c):
# find the surface normal given 3 vertices
@@ -317,6 +403,17 @@ Here is a function to calculate a triangle's normal in GDScript:
var normal = side1.cross(side2)
return normal
.. code-tab:: csharp
Vector3 GetTriangleNormal(Vector3 a, Vector3 b, Vector3 c)
{
// find the surface normal given 3 vertices
var side1 = b - a;
var side2 = c - a;
var normal = side1.Cross(side2);
return normal;
}
Pointing to a Target
--------------------