Animating projectiles, balancing orbital gravity, or keyframing objects along a path usually means endless trial and error. I got tired of guessing velocities and tweaking graph editors, so I built INERTIA.
It is a suite of three 100% native Geometry Nodes physics engines that handle the math, momentum, and collisions for you in Blender 5.1+.
The 3 Engines Included:
Projectiles (with Auto-Aim): Stop guessing launch angles. Select a target object, and the built-in iterative solver calculates the exact velocity and arc required to hit the bullseye. Includes friction, aerodynamic glide, and bounce/stick collisions.
Orbitals (N-Body Gravity): Create stable celestial mechanics with zero keyframes. Built-in sub-stepping ensures your orbits are razor-thin and mathematically stable without spiraling out of control.
Curve Momentum: Ditch the robotic “Follow Path” constraint. Draw a Bezier curve and let real-world gravity drive. Objects accelerate downhill, lose momentum uphill, and automatically bank into sharp corners.
Predictive Paths: You can see the exact trajectory of your arrows and the orbital rings of your planets drawn as a glowing line in the viewport before you even press play.
Just wanted to share a quick workflow tip for anyone doing Vehicle Animation or Dynamic Camera Fly-throughs this week.
If you are using the standard Blender ‘Follow Path’ constraint, you probably know how robotic it looks. If a rollercoaster or a spaceship goes down a steep drop, you have to manually keyframe the graph editor to make it speed up, and then manually slow it down as it climbs the next hill.
In the INERTIA Suite , you can use the Curve Momentum engine to bypass this completely.
Just draw your Bezier curve, apply the modifier to your camera or vehicle, and let the built-in Gravity do the work. The object will automatically accelerate down steep slopes and naturally lose momentum when climbing uphill. You can even use the ‘Thrust’ slider to simulate an engine turning on and off!
Saves hours of graph-editor tweaking for fly-throughs.
The Curve Momentum engine is what caught my attention most. Using actual gravity to drive speed along a path rather than just following it at a constant rate is a much more natural result. Quick question - does the banking angle get calculated automatically from the curve curvature, or is it a manual parameter? Wondering how it handles really tight bends.
Hey Taisei! Glad the Curve Momentum engine caught your eye. That natural acceleration was exactly why I built it—keyframing gravity is a nightmare!
To answer your question: It is actually a hybrid of both, which gives you the best of both worlds.
The node tree automatically calculates the banking direction and pitch by reading the curve’s native Tangent and Normal data in real-time. It knows exactly how sharp the curve is.
However, because really tight bends can sometimes cause a vehicle to snap unrealistically fast, I exposed a manual ‘Banking Factor’ slider in the modifier. This acts as a multiplier on the automatic math.
You can leave it at 1.0 for true geometric banking.
You can dial it down (e.g., 0.3) for heavy vehicles like a train so it doesn’t tilt too violently on tight corners.
You can crank it up (e.g., 2.0) for aggressive, jet-fighter-style leaning.
Also, if your curve has really harsh, jagged corners, you can use the built-in ‘Resample Curve’ slider to smooth out the physics calculations on the fly without having to redraw your track.
Let me know if you have any other questions about it!
That’s a really elegant solution - auto from the curve geometry but with a multiplier to tune the feel. The train vs jet-fighter example makes total sense. Going to try this out.
wesome to hear! Definitely let me know how it feels once you get it in your scene.
If you end up rendering a cool animation with it, feel free to share it here or drop it in the Discord—I always love seeing how people push the tools. Have a great weekend!
Projectiles (with Auto-Aim): Stop guessing launch angles. Select a target object, and the built-in iterative solver calculates the exact velocity and arc required to hit the bullseye. Includes friction, aerodynamic glide, and bounce/stick collisions.
Orbitals (N-Body Gravity): Create stable celestial mechanics with zero keyframes. Built-in sub-stepping ensures your orbits are razor-thin and mathematically stable without spiraling out of control.
Curve Momentum: Ditch the robotic “Follow Path” constraint. Draw a Bezier curve and let real-world gravity drive. Objects accelerate downhill, lose momentum uphill, and automatically bank into sharp corners.
Predictive Paths: You can see the exact trajectory of your arrows and the orbital rings of your planets drawn as a glowing line in the viewport before you even press play.
