boyquotes/gd3dtopdown

3D top down character controller for the Godot game engine with GDExtension

GD3Dtopdown

Top down 3D controller for the Godot Game Engine using GDextension (Godot 4 beta 8.0, will update until release)

This is a character controller that I'm using in a personal project. Decided to share it since It's using GDExtension and might be of use to someone should they get stuck.

It also showcases a solution for top down 3D games where the camera can be rotated around the caharacter and buildings can be entered. Hiding walls and roofs and making them transparent to mouse raycasts.

Installation

Compiled from source (Debug)

This guide assumes you have the required C++ compilers and SCons installed, explained in the godot compiling guide.

Clone the project with submodules

git clone --recurse-submodules [email protected]:jquinl/gd3dtopdown_project.git

The source library is in gd3d_example/addons/lib/gd3dtopdown/ here you can find the SConstruct file, which needs the godot-cpp submodule in the same folder gd3d_example/addons/lib/gd3dtopdown/godot-cpp

cd gd3d_example/addons/lib/gd3dtopdown/
scons target=template_debug

With this, the example project should work already.
If your project has a different folder system:

1. The binary will be placed in gd3d_example/addons/bin

2. The needed .gdextension file can be found in gd3d_example/addons/lib/gd3dtopdown.gdextension make sure you place it inside your folder and modify it to match the location of the binaries in your project.

3. Include a .gdignore file to avoid reloading the engine when new .obj files are generated.

Example

The example consists of 3 scenes, the main scene, the character scene and a building scene.

Character scene (res://scenes/GD3Dexample.tscn)

Description

The scene root is a CharacterGD3D node. It has a collision shape, animator tree, animator and model children nodes, as well as a camera and two nodes used to detect building interiors and walls. It also includes a gdscript example (res://scripts/gd3topdown.gd) with the movement function.

How it works

The character can interact with other nodes, also implemented in this plugin.

1. SelectableGD3D: When the mouse is over the object and aiming (Rigth click in the example).

2. VisualObstacleGD3D: When a VisualDetectorGD3D node enters the area this node will signal its children.

3. InteriorAreadGD3D: When a InteriorDetectordGD3D node enters the area this node will signal its children.

4. TweenMeshInstanceGD3D: When setup under a VisualObstacleGD3D node and receiving an entered signal this will perform a dissolve effect of the mesh, if shader parameters are set.

Remember to set the collision masks accordingly.

The character has a mask for collision detection, its used when aiming.

Because of this, the VisualObstacleGD3D and InteriorAreadGD3D collision masks cannot be the same as the Character Aiming mask. However objects that can be detected and interacted with can be in both of those layers.

Building scene (res://scenes/buildings/house.tscn)

Description

This scene showcases how to order nodes in order to achieve a multy story building, and have the walls and roof of stories on top of the character dissapear without having to come between the camera and the character.

How it works

Here the nodes VisualObstacleGD3D and InteriorAreadGD3D are used together in order to achieve the desired result.

Two InteriorAreadGD3D nodes and several VisualObstacleGD3D are used in the scene.
Any VisualObstacleGD3D node that is childed to a InteriorAreadGD3D will dissapear when that area is entered by a InteriorDetectordGD3D.
A VisualObstacleGD3D can be childed to several InteriorAreadGD3D nodes. And will check wether the character changed to any of the areas it is childed to before dissapearing or reappearing, avoiding weird artifacts when two areas overlap.

If the child TweenMeshInstanceGD3D of the visual obstacle has a shader material used for making the wall invisible, you can supply it with the parameters for the shader and the node will use two tweens to appear and dissapear the mesh (or any other effect you can think of) and will do so while keeping track of the progress of the effect. Which will prevent pops.

An invisible mesh casting shadows overlaps the building, which allows the nodes to dissolve without having to cast shadows.

Main scene (res://scenes/main_scene.tscn)

This is the main scene. It has a VisualObstacleGD3D node without parent (will only disspear when colliding with a VisualDetectorGD3D), the house, a SelectableGD3D and the character as well as green selectable box.

The SelectableGD3D will simply emit a signal when the mouse is aiming and hovers over it, stops hovering over it. Or is hovering over it and the aiming stops. (res://scripts/selectable_node.gd)

Node structure

graph LR
A(Area3D) --> B(InteriorAreadGD3D)  
A(Area3D) --> B(InteriorDetectordGD3D)  
A(Area3D) --> B(VisualDetectorGD3D)  

graph LR
A(StaticBody3D) --> B(VisualObstacleGD3D)  
A(StaticBody3D) --> B(SelectableGD3D)  

graph LR
A(CharacterBody3D) --> B(CharacterGD3D)  

Each node has a separate file in gd3d_example/addons/lib/gd3dtopdown/src. An additional file helpers_gd3d.hpp is used in order to centralize the values of the signals passed around internally, processed with the _notification(int) function.