Physion 0.8.4 adds Visual Filters: 35 effects that any Node can wear, from a glow or a drop shadow to CRT scanlines, a halftone pattern or a shockwave that ripples out of a body when it lands. Select a Node, switch a filter on, and it is drawn that way from then on, in the editor and while the simulation runs.

You can see all of this for yourself in a live demo scene, already set up with a filter on each body.

The filters are purely visual. They change how a Node looks, not how it behaves: a glowing ball has the same mass, shape and bounce as a plain one, and a shockwave that visibly bends a box does not actually move it. That makes them safe to use anywhere, from a single body you want to stand out to a whole scene you want to look like a 1980s monitor.

This post covers what each filter does, how the editor works, and which of them animate.

A free body diagram is the first thing a mechanics course teaches and the last thing a student wants to draw. Physion can now draw one for you, from the real forces in a running simulation: select a body, switch on the forces you care about, and each one appears as a labelled arrow, live, while the scene runs.

The arrows are measurements, not illustrations. Their magnitudes come out of the same calculation that puts the block where it is, so they are exactly as true as the motion you are already watching, and they change the instant anything else does. That turns a simulation from something to watch into something to read: a block sitting still on a ramp is not much of a lesson, but the three forces holding it there, labelled and adding up to nothing, is most of one.

The first half of this post covers what the feature does and every option it has. The second builds a real experiment with it, ready to take into a lesson.

If you've used Algodoo, you already know why it has such a loyal following: it's a genuinely good 2D physics sandbox with a long history, a huge community, and some features (optics especially) that go deeper than most alternatives. If you're reading this, there's a good chance you searched for something like "algodoo alternative," "algodoo online," or "algodoo no download," which usually means one specific thing: you want to skip installing anything and just start building.

That's the honest, direct comparison this post is trying to be. Physion and Algodoo solve a lot of the same problem, drawing shapes, connecting them with joints and springs, watching physics happen, but they make different tradeoffs. We'll cover both fairly: what each one does well, where Algodoo is still ahead, and where Physion's browser-first design changes the equation.

Multiply or Release is a popular physics-based simulation genre originally created by MIKAN in 2021 that combines marble racing with strategic territory warfare. The concept is simple but addictively watchable: marbles fall through a Plinko board, landing on either a Multiply zone (which doubles the ammunition) or a Release zone (which fires all accumulated bullets at enemy territory). The tension builds with each multiplication: will a team release early with a weak attack, or risk waiting to multiply into the hundreds for a game-changing assault?

Since MIKAN's original videos popularized the format, countless creators have built their own variations using tools like Algodoo, Unity and Physion. The genre has exploded across YouTube thanks to its perfect blend of unpredictability, strategic depth, and satisfying visual payoffs when hundreds of bullets fire simultaneously to capture enemy territory.

We're super excited to bring you Particle Life in Physion: a mesmerizing simulation where particles interact through simple attraction and repulsion forces, creating surprisingly organic patterns and behaviors. It's a beautiful demonstration of how complexity emerges from simplicity and it's really fun to play with.

Physion is now equipped with audio support, thanks to the integration of the Tone.js library. In this blog post, we'll briefly explain what Tone.js is and how you can use it to enhance your Physion projects with audio.

While most of Physion's features are easily accessible through a user-friendly graphical interface, audio support, at least for now, is accessible exclusively through scripting. This means that you won't find a convenient UI tool for adding an "audio component" to your scenes. Instead, you'll need to import the audio library into your scripts and use it to create various sounds and audio effects. Let's dive into the process.

A feature that up until now was missing from Physion was the ability to create graphs. With graphs we can easily interpret data and better understand how properties of objects participating in our simulation change over time.

Up until now, the physics engine used by Physion was Box2D. Box2D is an open source 2D physics engine written in C++ and it is used in many games and apps.

Although Box2D is a mature physics engine with many features, it doesn't "natively" support fluid simulation. After some research on the web, I came across LiquidFun. As mentioned in LiquidFun's website:

LiquidFun is an extension of Box2D. It adds a particle based fluid and soft body simulation to the rigid body functionality of Box2D.

As it turns out, transitioning from Box2D to LiquidFun is quite easy. All the features supported in Box2D are also supported in LiquidFun so there's no need for any major code changes when switching to LiquidFun.

Although LiquidFun supports a rich set of features, we will start simple; the transition to LiquidFun will have one simple goal: Allow the user to convert a rigid body into a liquid or an elastic (soft) body.

A new (BodyNode) property was recently added in Physion.

Its name: Gravity Scale (gravityScale).

As the name suggests, the gravityScale property of a body can be used to "scale" the gravitational attraction applied to it. In other words, the gravityScale allows you to specify a different gravity for each body.

By default, the value of this new property is 1.0 meaning that the Scene's gravity will be applied to the body. If you change this value to say 0.5 then only half of the Scene's gravitational force will be applied to the body. If you want to make a body float (i.e ignore gravity) you can set a gravity scale of 0. To make a balloon-like body you can set its gravityScale to a negative number.

Recently, a feature request was made in Physion's Discord Server: "Add the ability to visualize the trajectory of an object". This functionality was already implemented in the old version of Physion as you can see in the video below:

Unfortunately (and for the time being) the web version of Physion doesn't natively support tracers. The goods news is that we can implement the tracer functionality using scripting.