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Reply From: |
Matt Greer |
Here is a simple way to do it
extends KinematicBody2D
const SPEED = 120
func _physics_process(delta):
var mouse_pos = get_global_mouse_position()
look_at(mouse_pos)
var angle = position.angle_to_point(mouse_pos)
var direction = Vector2(cos(angle), sin(angle))
if Input.is_action_pressed("ui_up"):
direction *= -SPEED
if Input.is_action_pressed("ui_down"):
direction *= SPEED
move_and_slide(direction, Vector2.UP)
To move your player you need a vector that is pointing in the direction you want to move it. That’s what direction is, it is a vector of length 1 pointed towards where the mouse is. Then by multiplying that vector by the speed value, you end up with how much the player needs to move along x and y to get to where the mouse is.
This is a very simple implementation, but it gets the idea across. You will probably want acceleration and friction and all that good stuff to make the movement more smooth and natural.
Here is a tiny Godot project with the above code in it:
https://github.com/city41/GodotMoveTowardsMouse
Also, I took the player sprite and rotated it 90 degrees. That way the look_at(mouse_pos) does what you expect. That is a pretty quick and dirty way to fix that problem, but it works.
thank you, this is working! Could you explain in further detail these to code lines?
var angle = position.angle_to_point(mouse_pos)
var direction = Vector2(cos(angle), sin(angle))
I’m not sure what cos, sine, or position.angle_to_point do, and I think that it’s important that i understand how its working so I can do further implementation. Thanks for your answer. 
Millard | 2020-09-12 21:43
also, I’m having trouble implementing left and right movement.
Millard | 2020-09-12 22:09
This is all using trigonometry to accomplish the movement. I’m not sure how well equipped I am to explain trig
Your player’s position is a vector, which Godot calls a Vector2. It looks just like a point with an x and a y coordinate, but vectors are more than that. They are basically a way to describe in what direction something is pointing.
Angles also describe how something is pointing, they are kind of the opposite of vectors. So if the mouse cursor is in the upper right of the screen, and the player is down in the lower left, then the mouse cursor is about 45 degrees from the player.
var angle = position.angle_to_point(mouse_pos) is taking two vectors (the player’s position and the mouse cursor’s position), and figuring out what the angle is between them. Like in the above example, it’d figure out 45 degrees.
Once you have an angle, you can convert it into a vector. cos and sin are trig functions that help with that.
var direction = Vector2(cos(angle), sin(angle)) took the angle (45 degrees) and converted that into a vector.
Once you have the proper vector, you can give it to Godot and it will use it to move your character. Godot uses vectors for a lot of things, in this case it is using it for movement.
If you want to learn more, doing a Google search for “trigonometry for game developers” turns up a lot of stuff. Here is a tutorial I just found that looks like it might be good:
Trigonometry for Game Programming: Part 1/2 | Kodeco
If nothing else, that tutorial explains sin and cos
Matt Greer | 2020-09-12 22:16
For left and right movement, I assume you want to “strafe”? This would take more trigonometry to pull off.
The angle we calculated above is the angle from the player to the mouse. If you want to player to move left, then you basically take that angle and subtract 90 degrees from it, convert it to a vector, magnify the vector by multiplying it with SPEED, then passing it to move_and_slide.
Unfortunately there is another wrinkle, Godot uses radians, not degrees. They are just another unit for measuring angles. So you’d need to take angle, and subtract pi/2 from it to get the proper angle value.
Having a grasp of some basic trig will help with game programming and help with understanding how Godot works.
Matt Greer | 2020-09-12 22:24
