Added spring arm node #18822

QbieShay · 2018-05-12T18:22:58Z

Thanks to @AndreaCatania, Godot now can have a Spring Arm node!
Closes #16508.

The spring arm node is a node that pushes all its children back on his local z considering collision with the environment. If there is a collision, the spring arm will reduce its length.
The spring arm only moves its immediate children, and only the location( rotation control it's left in the hands of the developer ). It supports collision masks and specific body exclusion. It has a shape as property which is the shape that will be cast to do collision avoidance. Multiple shapes are not supported.

This type of node comes in handy when making 3rd person cameras, but it's not bound to that.

Example usage:

A classic responsive 3rd person camera can be achieved by simply adding the spring node as a child of the character, regulating its orientation to match the desired angle, and adding a camera as a child of the spring arm node. This implementation can be modified in various ways, for example, moving the spring arm on the shoulder of the character will achieve a shoulder camera with minimal effort.

The spring arm itself does not move on his own, so it is possible to control its motion , for example, for a racing game it's useful to have damping on the camera movement, and this can be easily achieved by scripting the spring arm node.

ghost · 2018-05-13T10:04:17Z

scene/3d/spring_arm.cpp

@@ -0,0 +1,141 @@
+/*************************************************************************/
+/*  spring_arm.h                                                         */


should be .cpp

QbieShay · 2018-05-13T19:03:28Z

corrected the license, also added a method to get the current spring length.

vnen · 2018-05-13T19:35:06Z

build.bat

@@ -0,0 +1,3 @@
+@echo off
+call "C:\Program Files (x86)\Microsoft Visual Studio\2017\BuildTools\VC\Auxiliary\Build\vcvarsall.bat" amd64
+scons p=windows


This file was added by mistake.

QbieShay · 2018-05-13T19:40:21Z

@vnen, yeah, sorry. Fixed

AndreaCatania · 2018-05-13T20:40:33Z

I think that is better if you initialize current_spring_length to 0 and mask to 1 ( that is the same value of all other physics body)
This line is not required : excluded_objects = Set<RID>();
In the header you have to reorder correctly "set" and "get" functions

QbieShay · 2018-05-14T10:38:16Z

Done :)

reduz · 2018-05-27T15:51:01Z

This looks nice, but I'm not sure this should be core, it does not seem like something you will use very often and could be very well provided by a script in the asset library

Zireael07 · 2018-05-27T16:36:40Z

Most 3D games will probably use this, @reduz

QbieShay · 2018-05-27T16:55:13Z

@reduz i think it would be nice to have, i felt the need for this and i think also the people in #16508 did :)
With @AndreaCatania modifications, this code is simple, lightweight, and very general purpose anyway.

silverweed · 2018-05-27T17:13:36Z

I agree with @Zireael07 and @QbieShay, imho it'd be more convenient to have it core rather than having to import it every time. Moreover, for something as performance-intensive as a spring arm, to me C++ appears as a better choice than gdscript.

AndreaCatania · 2018-05-28T08:24:33Z

@reduz is saying correctly, but I think that it will make life easier for all the people that want to avoid camera overlapping with environment. Is not a lot of code and i think worth it

ghost · 2018-05-28T14:42:07Z

This is useful unless the game is in first person or camera movement is deterministic. I don't think I can make unobscured third person view without implementing something similar to this, and doing so takes a considerable amount of time and coding skill. I think it is justified according to this.

fire · 2018-07-24T16:45:09Z

Is anyone interested in adding enabling camera lag for location and rotation?

There's camera lag speed, camera rotation lag speed variables and a max camera lag distance.

Bonus points for adding arm debugging helpers.

The reason is that the arm motion is abrupt.

QbieShay · 2018-07-24T16:47:58Z

Hey @fire, achieving camera lag shouldn't bee to complicated: you place a dummy object under the spring arm node and you make your camera follow it with the lag you prefer. I believe you can also use an interpolated camera and have it out of the box

fire · 2018-07-24T17:43:50Z

It's working.

I placed a dummy CameraTarget as a child of the spring arm node, then put the interpolated camera somewhere not as a child of the spring arm node. (its location should be close to the controlled mesh, this defines the minimum camera distance.) and set the interpolated camera's target to be CameraTarget.

reduz · 2018-07-24T18:38:50Z

@QbieShay A lot of users really insisted about this feature, so in the latest PR meeting review we have decided to merge it, as such, I will review it for inclusion.

reduz · 2018-07-24T18:40:18Z

scene/3d/spring_arm.cpp

+				set_process_internal(false);
+			}
+			break;
+		case NOTIFICATION_INTERNAL_PROCESS:


this should be INTERNAL_PHYSICS_PROCESS, because then you make sure that physics world is available for raycasting (as in, may happen that thread physics is enabled and you will get an error). You also need to use set_physics_process_internal()

If physic process is used and the spring arm is used for a camera, the difference between physic process and regular process is visible to the user and annoying. See here you can try out a spring arm that uses physic process

reduz · 2018-07-24T18:45:58Z

scene/3d/spring_arm.h

+public:
+	void set_spring_length(float p_length);
+	float get_spring_length() const;
+	void set_shape(Ref<Shape> p_shape);


Is setting a shape worth it? I would honestly just use a raycast with a margin, this covers pretty much any case I can think of.

I looked in the physics server but I don't see a way to set a margin for a raycast

reduz · 2018-07-24T18:47:30Z

scene/3d/spring_arm.h

+	bool remove_excluded_object(RID p_rid);
+	void clear_excluded_objects();
+	float get_current_spring_length();
+


I would also set a node via NodePath that you want to automatically make the SpringArm change position to on every frame (usually a camera). Could be a function like

set_target_node(const NodePath&) NodePath get_target_node() const

The movement of the spring arm node is intentionally left to the user. In order to achieve what you mention, it is enough to put the spring arm node as a child of a remote transform or the object itself. Leaving the movement to the user also allows for adding manual lag - damping - ecc.

reduz · 2018-07-24T18:48:35Z

scene/register_scene_types.cpp

@@ -390,6 +391,8 @@ void register_scene_types() {
 	ClassDB::register_class<RigidBody>();
 	ClassDB::register_class<KinematicCollision>();
 	ClassDB::register_class<KinematicBody>();
+	ClassDB::register_class<SpringArm>();


I think you should probably add a gizmo to this, where you can edit the length (and optionally the margin if you use that)

Can you point me to an example of where this is done? I have no idea on how to implement that. Probably also @groud can help me?

check the ray shape gizmo, I think that you can copy most part of code from there

@AndreaCatania I'm not sure the ray shape gizmo is that good, I opened an issue on that here

It can be improved, but the basic code is almost the same

reduz · 2018-07-24T18:49:22Z

scene/3d/spring_arm.h

+	void add_excluded_object(RID p_rid);
+	bool remove_excluded_object(RID p_rid);
+	void clear_excluded_objects();
+	float get_current_spring_length();


I would use a get_hit_length() function or similar, instead of get_current_sprint_length(), to make it less confusing

reduz · 2018-08-10T16:27:43Z

Gizmos changed recently due to @JFonS , so this will need re-adapting to the new way gizmos are done.
Once conflicts are fixed, I will merge it. I will also probably test it well on a few scenarios and existing demo scenes and possibly do small changes, but I think as is this is good.

JFonS · 2018-08-10T16:32:53Z

@QbieShay you can take the new RayCastSpatialGizmoPlugin as an example on how to convert your gizmo, and ask away if you have any doubts.

aaronfranke · 2018-10-17T03:20:45Z

This Node is lacking an icon.

yushgh · 2019-07-22T21:48:40Z

This Node is lacking an icon.

I made one by modifying <damped spring joint 2d> and just leave it here.

icon_spring_arm.zip

QbieShay force-pushed the master branch from fe95dd5 to 536a309 Compare May 12, 2018 20:01

groud added feature proposal topic:physics labels May 12, 2018

QbieShay mentioned this pull request May 13, 2018

Spring Arm Node #16508

Closed

ghost reviewed May 13, 2018

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QbieShay force-pushed the master branch from 536a309 to f527f63 Compare May 13, 2018 19:01

vnen reviewed May 13, 2018

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QbieShay force-pushed the master branch from f527f63 to 294e8bb Compare May 13, 2018 19:37

QbieShay force-pushed the master branch 2 times, most recently from 3ea6202 to 292e489 Compare May 13, 2018 21:25

karroffel added this to the 3.1 milestone May 14, 2018

mhilbrunner mentioned this pull request Jun 10, 2018

Problems with preventing "engine bloat" and the AssetLibrary #19486

Closed

vnen mentioned this pull request Jun 12, 2018

'First Person' and 'Third Person' character controller nodes #19506

Closed

reduz requested changes Jul 24, 2018

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QbieShay closed this Jul 28, 2018

QbieShay force-pushed the master branch from 292e489 to 90298dd Compare July 28, 2018 17:32

QbieShay reopened this Jul 28, 2018

QbieShay force-pushed the master branch 3 times, most recently from 8d4ed3e to 723f4df Compare July 30, 2018 11:13

QbieShay force-pushed the master branch from 723f4df to 35b5fb9 Compare August 6, 2018 17:02

QbieShay closed this Aug 18, 2018

QbieShay force-pushed the master branch from 35b5fb9 to f3c09b5 Compare August 18, 2018 10:41

QbieShay reopened this Aug 18, 2018

QbieShay force-pushed the master branch from 72cec6b to 1e711c8 Compare August 18, 2018 12:26

added spring arm node.

bb14ef5

QbieShay force-pushed the master branch from 1e711c8 to bb14ef5 Compare August 18, 2018 12:34

reduz merged commit c1bd768 into godotengine:master Aug 20, 2018

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Added spring arm node #18822

Added spring arm node #18822

QbieShay commented May 12, 2018 •

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		@@ -0,0 +1,141 @@
		/*************************************************************************/
		/* spring_arm.h */

Added spring arm node #18822

Added spring arm node #18822

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