Boxed Physics

Boxed Physics is an implementation of the Box2D physics engine that allows for the use of joints, springs, sliders, and other complex physics interactions within your projects.

This documentation will guide you through the process of using Boxed Physics.

Working with Worlds

When using the Boxed Physics extension, you must initialize the physics environment before starting your project. To do this, use the Make world, Scale 1m: [SCALE] Gravity: [GRAVITY] Wind: [WIND] Scene: [SCENE] block.

Note: the environment is initialised to the default every time the project starts, but it's good practice to use this block every flag click anyways

Scene Types

The scene type determines the containment type for your physics world:

• Semi-closed stage: Prevents objects from leaving the bottom and sides of the stage but allows infinite upward movement.
• Closed stage: Fully contains objects within the stage, preventing them from leaving the top, bottom, or sides.
• Opened stage: Only prevents objects from falling off the bottom.
• Nothing: Removes all walls, allowing objects to move freely.

Changing World Options

Once the world is created, you can modify gravity and wind dynamically without creating a new world.

Additionally, you can enable slow motion using the Set slow motion to [VALUE] block.

Creating Your First Object

Objects in Boxed Physics are invisible physics-based hitboxes. To add an object, define its shape and attributes, and then create it in the world.

Basic Box Example

You can create multiple objects efficiently:

Other Shapes

Circles

Polygons

1. Costume-based: Directly convert the current costume into a polygon (no holes).
2. Point-based: Define polygons with a list of coordinates.

Defining Base Attributes

Customize objects with the Define base block:

• Type Determines if the object is static or dynamic.
• Density, Friction, Bounce Control physical properties like weight, surface interaction, and bounciness.

Modifying Objects

Damping (air resistance)

The damping of each object can also be changed with the Set [BODYATTR] of object [NAME] to [VALUE] block.

Destroying Objects

You can delete individual objects or clear all objects at once.

Moving Objects

Direct Movement

Velocity and Impulse

Rotational impulses are simple, just a number for power, but positional impulses are a little more complex.

Positional impulses can be one of two types: World Impulse or Impulse.
They both take a direction, and power, but they behave differently.
The Impulse option is meant for quick movements (like jumping)
while the World Impulse option is meant for movement over time (like pushing a wheel).

Making Joints

Joints connect objects and enable complex interactions like wheels, sliders and more.

You can create many types of joints, including:

• Rotating
• Spring
• Weld
• Slider

Experiment with all the joint types in this demo to see what they do.

Joint Properties

• Settable: Motor On, Speed, Limits, Torque
• Gettable: Angle, Speed, Torque, Tension

Performance Options

You can optimize your simulation by configuring iteration settings to allow for more objets with less lag, or have better physics with fewer objects.

While this doesn't visually change anything (usually) it does change how performant things are, and you will notice that with bigger simulations.

Math Utilities

Boxed Physics also includes some math blocks for convenience:

• Rotate a point: Rotate a point around the origin (0, 0).
• Get rotation from: Find the direction from one point to another.
• Magnitude: Calculate the vector length.
• Distance: Measure the distance between two points.

Examples

Need more help?
Try some example projects here.