https://github.com/yoyoengine/p2d
A 2D rigidbody physics system written for yoyoengine
https://github.com/yoyoengine/p2d
2d physics-engine yoyoengine
Last synced: 4 months ago
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A 2D rigidbody physics system written for yoyoengine
- Host: GitHub
- URL: https://github.com/yoyoengine/p2d
- Owner: yoyoengine
- License: mit
- Created: 2024-12-28T18:31:50.000Z (7 months ago)
- Default Branch: main
- Last Pushed: 2025-02-02T23:45:15.000Z (5 months ago)
- Last Synced: 2025-02-03T00:26:00.897Z (5 months ago)
- Topics: 2d, physics-engine, yoyoengine
- Language: C
- Homepage:
- Size: 149 KB
- Stars: 2
- Watchers: 0
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
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---
A 2D rigidbody physics system written for yoyoengine.
## Features
- Broad phase collision detection, using a hashed spatial grid
- OOB and Circle collision detection and resolution
- Collision and trigger callbacks
- Easy synchronization with existing ECS
- Frustum-culled sleeping objects
- Spring and Hinge Joints
- Collision layers
> [!WARNING]
> Internal rotations are stored in degrees (not radians!) so make sure you convert properly.
## Usage
```c
#include
// example collision callback
void collision_callback(struct p2d_cb_data* data) {
// ...
}
// example trigger callback
void trigger_callback(struct p2d_cb_data* data) {
// ...
}
// at some point during init
p2d_init(..., trigger_callback);
// create and register objects
// ...
struct p2d_object obj = {0};
obj.type = P2D_OBJECT_RECTANGLE,
obj.x = 100;
obj.y = 200;
obj.vx = 100;
obj.out_x = &YOUR_ECS_X;
obj.out_y = &YOUR_ECS_Y;
obj.out_rotation = &YOUR_ECS_ROTATION;
obj.mask = P2D_LAYER_1 & P2D_LAYER_2;
p2d_register_object(&obj);
// ...
// in your engine update loop: (run this at the hz you want your physics to run at)
p2d_step(physics_delta_time);
// before quitting, shutdown
p2d_shutdown();
```
## Future work
| Item | Description | Priority | Progress |
|---------------------|---------------------------------------------|----------|-----------------|
| Debug Resolution | The current basic resolution has edge cases | High | Done |
| Rotation Resolution | Implement rotation and torque | High | Done |
| Friction Resolution | Implement friction | High | Done |
| Joints | Constraints between objects | High | Mostly Done |
| Collision Layers | Specify what can collide with what | Medium | Mostly Done |
| Advanced Gravity | Allow seperate spatial fields of gravity | Low | Maybe Later |
| New Shapes | Implement planes for more complex shapes | Low | Maybe Later |
| Optimization | Micro-optimize for performance | Low | Maybe Later |
| Add "True" Sleeping | Standstill objects get optimized out | Low | Maybe Later |
## Testing
`cmake -DBUILD_P2D_TESTS=ON ..`
## Resources
Here are some resources that helped me along the way, which can hopefully be useful to you too!
- [(Book) Game Physics Engine Development](https://www.amazon.com/Game-Physics-Engine-Development-Commercial-Grade/dp/0123819768)
- [(Book) Real Time Collision Detection (Book)](https://a.co/d/g9Rpjsk)
- [(Youtube) Two-Bit Coding Physics Engine Playlist](https://www.youtube.com/playlist?list=PLSlpr6o9vURwq3oxVZSimY8iC-cdd3kIs)
- [(Articles) Rigid Body Dyanmics - Chris Hecker](https://www.chrishecker.com/Rigid_Body_Dynamics)
- [(Reference Example) Box2D](https://github.com/erincatto/box2d-lite/tree/master/Box2D)
## Advice
If I were to write this again from scratch, I would:
- Avoid writing a physics engine at all, unless I was doing it for fun or learning (it's really really hard)
- define rectangles by half extents, because their x,y position should be the center, not the top left (mixing with circles that have x,y as center is a huge pain)
- use radians instead of degrees internally (the conversion is a big failure point)