Rope Sim

Workflow

Rope Sim couldn’t be any easier to use. Here’s a simple step-by-step outline to get you started:

1. Create a new composition.
2. Create a new solid.
3. Add the Rope Sim Effect to your solid.
4. Add a mask to your solid if you wish to use colliders, set the mask mode to "None", and specify the mask in the collision options.
5. Preview the animation.

Rope Sim uses masks for colliders. If your path is currently a shape, you can easily convert it into a mask using Create Mask From Shape located in the Layer menu. If your mask has animation, this will also carry through into your animation.

Rope Sim is a physics simulator. As such, it must recalculate the entire sim each time the frame is changed. While it features outstanding performance, it will begin to slow down the longer the animation is. Adding colliders will also slow down performance as it must perform collision checks.

Getting a good simulation is a combination of the right number of segments and substeps. For example, tearing will have different stress points depending on these factors. Colliders will behave differently – sometimes more accurately, other times less so. Forces will also have different impacts based on these factos.

If a simulation is changed midway through a cached sim, you may need to clear the After Effects cache to produce a new, clean result as After Effects may still have part of the older simulation stored in cache.

Rope Sim does not support motion blur natively. To use motion blur, simply add an adjustment layer and apply the Pixel Motion Blur effect to the layer.

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Main Parameters

This category contains the fundamental parameters you’ll be using most of the time – chain point positions and attachments. These are among the most powerful parameters within the plugin. They allow you to control the general behavior of the rope and dictate whether it should be hanging, dangling, or even both. Both the start and end points can be keyframed at any time so that the rope can be moved, stretched, swung, spun, or collided with masks. More importantly, any point can be detached or re-attached using keyframing at any time. For example, the second point can be detached, so that the rope falls and swings, followed the first point detachment, causing the rope to fall. Finally, the points can even be re-attached mid-way through the timeline which allows the rope to have fallen, and then picked up again.

Keyframe the attachment point and simulate instant, beautiful secondary motion.

Point A: This determines the primary X and Y coordinate for the start of the rope in your composition space. You can keyframe this position to attach the rope to a moving object, like a swinging crane arm or a character’s hand.

Point B: This determines the secondary X and Y coordinate for the end of the rope.

Point A Attachment: This determines whether the rope is physically pinned to Point A. Unchecking this box, especially when keyframed, releases the rope from this specific point, allowing it to detach and swing downwards based on gravity and momentum.

Point B Attachment: This dictates whether the rope is pinned to Point B. If both Point A and Point B attachments are disabled simultaneously, the entire rope will enter a free-fall state and plummet through the composition. Adding collider masks below can produce unique results as the rope can bounce, stick, or slide with it.

Physics

This core category houses the fundamental properties that dictate how the rope behaves in its environment. By adjusting these settings, you can define the material feel of the simulation, transforming a light string into a heavy chain. The number of segments and the substeps are probably the single two most important parameters in this section and they work together hand-in-hand to produce different results. A high number isn’t always desirable and a lower number of rope segments, for example, can create a smoother rope, albeit less accurate.

Adjust rope elasticity (left) or modify damping (right) to simulate different materials.

Segments: This controls the underlying resolution of the rope simulation by dividing the total length into smaller, rigid links. A lower segment count creates a stiff, blocky chain, while a higher segment count yields a highly flexible, smooth cable, though it requires slightly more processing power to calculate. The segment count also affects forces and collision accuracy.

Rope Length: This dictates the total resting length of the simulated cable, independent of the actual distance between Point A and Point B. For example, if your anchor points are 500 pixels apart on screen but your rope length is set to 1000, the rope will naturally sag heavily in the middle, creating a deep, realistic U-shape.

Gravity: This sets the directional force pulling the rope downwards. A higher value simulates a heavier, denser material, while negative values can be used to reverse gravity entirely, making the rope float upwards like an underwater kelp stalk or a helium balloon string.

Elasticity: This defines how stretchy the material is when put under tension. A value near zero simulates a rigid steel cable that refuses to stretch, whereas a higher value creates a bouncy, rubber-band effect when the rope is pulled taut.

Damping: This applies simulated air resistance or friction to the rope’s movement, causing it to lose energy over time. High damping is excellent for simulating ropes submerged in viscous fluids like water or oil, as it forces the swinging rope to settle into its resting position much faster instead of swinging endlessly. A damping value of 0 would mean the rope would never come to a complete standstill.

Substeps: This critical parameter determines how many times the physics engine calculates collisions and forces between every rendered frame. If your rope is passing right through your collision masks or jittering wildly under high tension, increasing the substeps will drastically improve the accuracy and stability of the simulation by giving the engine more time to correct physics errors.

Pre-roll Frames: This forces the simulation to calculate physics for a set number of frames before the timeline actually begins. This is particularly useful if you want your rope to start in a fully settled, resting state rather than falling awkwardly into place exactly at frame zero of your animation.

Enable Self-Collision: This prevents the rope from clipping through its own geometry. When enabled, the rope will realistically fold, stack, and coil upon itself when dropping onto a surface, rather than phasing through its own segments.

Self collisions disabled (left), self collisions enabled (right).

Appearance

This category controls the visual rendering of the rope once the physics simulation is complete. It dictates how the underlying math is drawn onto your After Effects composition. Using the options in this group, the rope can be tapered so that it can represent a tail, hair or a tentacle.

Simulate secondary action such as clothing elements like the neck tie shown below.

Thickness Start: This sets the width, in pixels, of the rope at Point A.

Thickness End: This sets the width of the rope at Point B. By using different values for the start and end thickness, you can easily create organically tapering shapes like vines, tentacles, or a rat’s tail.

Rope Color: This determines the solid color used to render the rope segments.

Display Segment Nodes: This renders distinct circular indicators at each physics segment joint along the rope. It is primarily used as a technical diagnostic tool to see exactly how the physics engine is calculating the rope’s curve.

Composite On Original: This blends the rendered rope directly over the original source image of the layer. If disabled, the plugin will render the rope on a perfectly transparent background, ignoring whatever pixels were originally on the layer.

Collision Options

This group allows your simulated rope to physically interact with the environment defined by your After Effects masks. It bridges the gap between the simulated rope and the rest of your composition. Colliders allow for physically-correct rope interactions with various shapes – even custom drawn ones. Since the shapes are vector-based, accurate collisions are calculated since Rope Sim computes correct angles on impact. You are not limited to just one shape – you can have as many as you want so that it’s a breeze creating full interactive environments for your simulations.

Collision Mask: This dropdown allows you to select a specific path drawn on your layer to act as a physical barrier. The rope will dynamically bounce off or rest upon the contours of this mask.

Use All Masks: This overrides the single mask selection and forces the physics engine to treat every single mask path on the layer as an active physical collider.

Collider Static Friction: This determines how much horizontal force is required to get a resting rope to start moving across a collider’s surface. A high value means the rope will grip the surface tightly and resist being dragged by gravity or wind.

Low collider kinetic friction (left), high collider kinetic friction (right)

Collider Kinetic Friction: This dictates how much sliding resistance is applied while the rope is actively moving along a collider. Increasing this value makes the collider surface feel rough like sandpaper, causing the rope to drag and slow down as it slides.

Low collider bounce (left), high collider bounce (right)

Collider Bounce: This controls the restitution, or springiness, of the collision surface. A high bounce value will cause a dropped rope to ricochet off the mask upon impact, much like a rubber hose hitting a concrete floor.

Collider stickiness with low threshold level.

Collider Stick: This defines an interactive threshold that temporarily pins the rope to the collider until a specific amount of tension forces it to pull away. This is incredibly useful for simulating sticky organic materials like spiderwebs or slime threads that adhere to a surface until forcibly yanked off by a moving anchor point.

Wind Options

This category provides an external, directional force field that pushes the rope globally, perfect for simulating weather or chaotic environmental turbulence. Keyframing the wind parameters will produce physically-accurate results since the rope will react accordingly. Just like real-world wind effects, Rope Sim provides turbulence for varying wind intensities as well as wind frequency for control over the scale.

Upward wind with colliders (left), sideward wind with colliders (right).

Wind Intensity: This sets the base strength of the wind pushing against the rope.

Wind Direction: This angle parameter determines the global direction the wind is blowing towards. By combining high intensity with specific angles, you can simulate a strong cross-breeze, an updraft lifting the rope, or a downdraft pushing it flat against a surface.

Wind low turbulence frequency (left), wind high turbulence frequency (right).

Turbulence Amount: This adds randomized, chaotic force to the baseline wind intensity. Instead of a steady, constant push, the rope will flutter and whip unpredictably, perfectly mimicking the chaotic behavior of a loose cable in a heavy storm.

Turbulence Frequency: This controls the speed and tightness of the turbulent waves acting on the rope. A lower frequency creates broad, slow swaying motions, while a high frequency causes rapid, tight vibrations along the entire length of the cable.

Tearing Options

This advanced mechanical group allows the rope to dynamically snap or break when the simulation forces exceed its structural limits. Tearing is an extremely powerful feature in Rope Sim. By specifying a threshold, you can control how much stress the rope can take before breaking. This allows you to simulate different threads such as fine wool or tough silk. Moreover, since tearing is dependent on segment stress, the rope can break using any number of means – by pulling it taut, by pushing a collider through it, or by dropping it. The tearing point will be completely different in every scenario, but always physically-accurate. Sometimes the rope will snap in the middle, while other times it will snap at one of the attachments points. If you display the segment points, you can specifically see where the tearing occurs.

Tearing by separating points and producing tension stress.

Tearing with collider producing tension stress.

Tearing with collider due to gravity impact tension stress.

Tearing: This checkbox activates the tearing system. When disabled, the rope is indestructible regardless of how much force, wind, or tension is applied to it.

Tear Threshold %: This sets the exact breaking point of the rope based on how much it stretches beyond its resting length. For example, setting this to 50% means the rope will physically snap in half if the physics engine forces any segment of the rope to stretch to 1.5 times its original resting size.

Changelog

• v1.0 – First release.