Table of Contents

1. About The Project
2. Features
3. Getting Started
   • Installation
   • Basic Usage
   • Creating Bodies
   • Shapes and Collision
   • Joints and Constraints
4. Contributing
5. Contributors
6. License

🎱 About The Project 🎱

Prowl.Drift is an open-source, MIT-licensed 2D physics engine built for the Prowl Game Engine. It provides a lightweight, high-performance physics simulation with support for rigid body dynamics, collision detection, and constraint solving.

Prowl.Drift follows a simple and intuitive API design, making it easy to integrate physics into your games and applications. Whether you're building a platformer, a physics puzzle game, or need realistic object interactions, Prowl.Drift has you covered.

Here's a basic example:

// Create a physics space
var space = new Space();

// Create a dynamic body with a box shape
var body = new Body(Body.BodyType.Dynamic, new Vector2(100, 50));
var boxShape = ShapePoly.CreateBox(0, 0, 32, 32);
body.AddShape(boxShape);
space.AddBody(body);

// Apply a force
body.ApplyForceToCenter(new Vector2(0, -500));

// Step the simulation (with solver iterations)
space.Step(1f / 60f, 8, 3, true); // dt, velocity iterations, position iterations, warm starting

✨ Features ✨

• General:

  • Cross-Platform! Windows, Linux & Mac!
  • 100% C#!
  • Built on System.Numerics for performance
  • Supports .NET 6, 7, 8, and 9
  • Highly Portable
    • Very easy to integrate
  • Lightweight and fast

• Physics Features:

  • Rigid Body Dynamics
    • Static, Kinematic, and Dynamic bodies
    • Mass, velocity, and angular velocity
    • Force and torque accumulation
    • Linear and angular damping
    • Fixed rotation support
  • Shape Support
    • Circles
    • Polygons (convex)
    • Line segments (With Rounded Thickness)
    • Multiple shapes per body (Compound)
  • Collision Detection
    • Broad-phase spatial hashing (Very Simple)
    • Narrow-phase SAT (Separating Axis Theorem)
    • Contact manifold generation
  • Constraint Solving
  • Joint System
    • Distance joints
    • Revolute joints (pin joints)
    • Prismatic joints (slider joints)
    • Weld joints
    • Wheel joints
    • Rope joints
    • Angle joints
    • Mouse joints (for dragging)

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🚀 Getting Started 🚀

Installation

dotnet add package Prowl.Drift

Basic Usage

Prowl.Drift is designed to be simple to use. Create a space, add bodies with shapes, and step the simulation.

using Prowl.Drift;
using System.Numerics;

// Create a physics space
var space = new Space();
space.Gravity = new Vector2(0, -10); // Set gravity

// Create the ground (static body)
var ground = new Body(Body.BodyType.Static, new Vector2(0, 400));
var groundShape = ShapePoly.CreateBox(0, 0, 800, 20);
ground.AddShape(groundShape);
space.AddBody(ground);

// Create a falling box (dynamic body)
var box = new Body(Body.BodyType.Dynamic, new Vector2(100, 50));
var boxShape = ShapePoly.CreateBox(0, 0, 32, 32);
box.AddShape(boxShape);
space.AddBody(box);

// Main game loop
while (gameRunning)
{
    // Step the physics simulation (60 FPS)
    space.Step(1f / 60f, 8, 3, true);

    // Use body.Position and body.Angle for rendering
    RenderBox(box.Position, box.Angle);
}

Creating Bodies

Bodies are the fundamental objects in the physics simulation. They can be static (immovable), kinematic (movable but not affected by forces), or dynamic (fully simulated).

// Static body (walls, ground, platforms)
var staticBody = new Body(Body.BodyType.Static, position);
space.AddBody(staticBody);

// Kinematic body (moving platforms, elevators)
var kinematicBody = new Body(Body.BodyType.Kinematic, position);
kinematicBody.LinearVelocity = new Vector2(50, 0); // Moves at constant velocity
space.AddBody(kinematicBody);

// Dynamic body (players, projectiles, physics objects)
var dynamicBody = new Body(Body.BodyType.Dynamic, position);
space.AddBody(dynamicBody);
dynamicBody.ApplyForceToCenter(new Vector2(0, -500)); // Apply force

Shapes and Collision

Bodies need shapes to participate in collision detection. Multiple shapes can be attached to a single body.

// Box shape
var boxShape = ShapePoly.CreateBox(0, 0, width, height);
body.AddShape(boxShape);

// Circle shape
var circleShape = new ShapeCircle(0, 0, radius);
body.AddShape(circleShape);

// Polygon shape (must be convex)
var vertices = new Vector2[] {
    new Vector2(-16, -16),
    new Vector2(16, -16),
    new Vector2(16, 16),
    new Vector2(-16, 16)
};
var polyShape = new ShapePoly(vertices);
body.AddShape(polyShape);

// Line segment
var segmentShape = new ShapeSegment(new Vector2(-50, 0), new Vector2(50, 0), 2); // thickness = 2
body.AddShape(segmentShape);

// Set material properties
boxShape.Density = 1.0f;
boxShape.Friction = 0.7f;
boxShape.Elasticity = 0.2f; // Restitution/bounciness

Joints and Constraints

Joints connect bodies together with various constraints.

// Distance joint - maintains fixed distance
var distanceJoint = new DistanceJoint(bodyA, bodyB, anchorA, anchorB);
space.AddJoint(distanceJoint);

// Revolute joint - pin joint, allows rotation
var revoluteJoint = new RevoluteJoint(bodyA, bodyB, worldAnchor);
revoluteJoint.CollideConnected = false; // Disable collision between connected bodies
space.AddJoint(revoluteJoint);

// Rope joint - maximum distance constraint
var ropeJoint = new RopeJoint(bodyA, bodyB, anchorA, anchorB);
ropeJoint.CollideConnected = false;
space.AddJoint(ropeJoint);

// Weld joint - rigid connection
var weldJoint = new WeldJoint(bodyA, bodyB, worldAnchor);
space.AddJoint(weldJoint);

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🤝 Contributing 🤝

Check our Contributing guide to see how to be part of this team.

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📜 License 📜

Distributed under the MIT License. See LICENSE for more information.

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