How to shoot where mouse/crosshair is pointing?

Schuster

Hello, for my Third person prototype I need help...... how can I shoot to the place where the mouse pointer is pointing? I spawning bullets from Position 3D node place in the front of the player. I have working solution for 2d but for 3d I didn't find an example of how to do it.

Kequc

For my "what is the mouse pointing at" implementation I added a raycast node set to cast to 0,0,-100 as a child of the camera, and then used something like this. You could probably figure out what object it is colliding with too pretty easily.

Any time the mouse moves the raycast is always underneath the cursor and pointed at whatever is directly underneath it.

extends Camera

onready var ray = get_node("ray")

var world_point := Vector3(-1, -1, -1)

func _input(event):
    if event is InputEventMouseMotion:
        ray.global_transform.origin = project_ray_origin(event.position)

func _process(delta):
    _point()

func _point() -> void:
    if (ray.is_colliding()):
        world_point = ray.get_collision_point()
    else:
        world_point = Vector3(-1, -1, -1)

Schuster

Thanks @Kequc...... I tried it this way

cam_ray = Vector3()
 func _input(event):
	if event is InputEventMouseButton:
		mouse_pos = level_camera.get_viewport().get_mouse_position().normalized ()
		mouse_pos = event.position
		cam_ray = level_camera.project_ray_normal(mouse_pos)

and in the bullet node script (i'm use Area node)

func _physics_process(delta):
	var target = Vector3()
	var bullet_speed = int(100)
	var bullet_dir = Vector3()
	target = mouse.cam_ray
	global_translate(bullet_dir.direction_to(target) * bullet_speed * delta)
	set_as_toplevel(true)

....this works but bullet it does not point directly at the center of the sight/crosshair....something is missing there but it's close.

Schuster

... here's the Unity engine point and shoot http://pressstart.vip/tutorials/2019/04/1/91/unity-point-and-shoot.html .....and Unreal engine Blueprint http://answers.unrealengine.com/questions/22611/top-down-mouse-driven-aiming-crosshair-follows-cur.html

TwistedTwigleg

I haven't done a 3rd person shooter myself, not directly at any rate, but looking at the Unreal blueprint and using what I have learned from other projects, I think I have a rough idea on how to go about it. I have no idea if it will work, nor have I tested any of the code, but here is how I would program it:

When you need to fire, send a raycast from the camera to the cursor location. This is needed so you can get the position in 3D space to aim the bullet at. Something like this should be able to get bullet location:

const RAY_LENGTH = 100
var raycast_position = null
func _physics_process(delta):
	# Note: this assumes you are using a action for the mouse.
	# you might need to replace this with a different method to detect
	# whether the mouse has been clicked.
	if (Input.is_action_just_pressed("mouse_click")):
		var mouse_position = get_tree.root.get_mouse_position()
		var raycast_from = level_camera.project_ray_origin(mouse_position)
		var raycast_to = level_camera.project_ray_normal(mouse_position)
		
		# You might need a collision mask to avoid objects like the player...
		var space_state = get_world().direct_space_state
		var raycast_result = space_state.intersect_ray(raycast_from, raycast_to)
		
		if (result):
			# store the location.
			raycast_position = result["position"]

Using the raycast position, the next step is to rotate the bullet so that it is pointed towards the raycast position. There are several ways to do this, but the easiest is probably to use the looking_at function in Transfom. For example:

if (raycast_position != null):
	# Assuming the bullet has been instanced already
	# and is stored in a variable called 'clone'
	# Note: for this to work, the bullet's position has to
	# already have been set, otherwise the rotation
	# will not be pointing to the correct spot.
	clone.global_transform = clone.global_transform.looking_at(raycast_position, Vector3.UP)

This will rotate the bullet so it's negative Z axis is pointing at the target, which means the bullet scene will need to be facing the negative Z axis for the visuals to look correct.

Then in the bullet script, all that is left is to move the scene along the negative Z axis. I think the translate_object_local function will move the object relative to it's rotation, though it has been awhile since I've used it:

func _physics_process(delta):
	var bullet_speed = int(100)
	translate_object_local(Vector3(0, 0, -bullet_speed))

Then the bullet should move towards whatever object is under the cursor.

I have not tested any of the code, but I think that should work, assuming I understand the situation and the code I wrote works correctly.

Hopefully this helps!

(Side note: I edited your post a bit so the code is formatted within your post)

Schuster

@TwistedTwigleg Wow,....this script works great....a lot of thanks for your help.

TwistedTwigleg

No problem, happy to help!

I wasn’t totally sure if the code I wrote would work to be honest, so I’m glad it was at least somewhat helpful.

MrOlioli

@TwistedTwigleg I try to use your way, but I get the wrong message that the result and level_camera are not declared

TwistedTwigleg

@MrOlioli said: @TwistedTwigleg I try to use your way, but I get the wrong message that the result and level_camera are not declared

Based on the message, I would say the issue is you have not defined level_camera. In the script I wrote, I assumed level_camera was the Camera node that the player sees. You need to get the Camera node (in something like the _ready function) and assign it to the level_camera class variable, like this:

var level_camera

func _ready():
	level_camera = get_node("CameraNodeHere")

Then that should fix the error message saying that level_camera is not defined :smile: