Groups and Drawings

Groups

Groups are colored rectangular regions that visually organize related components into logical units. They help you think in systems rather than individual components.

Creating groups

There are three ways to create a group:

Group tool - Press G to activate the group tool, then click and drag on the canvas to draw a rectangle
From selection - Select multiple components, then press Ctrl+G or right-click and choose Group selection
From template - Right-click empty canvas space and choose Insert group template to place a saved group

Double-click any group to edit its label and appearance.

Containment

Components are considered “inside” a group when their center point falls within the group bounds. This is intentionally forgiving so you don’t need pixel-perfect placement.

When you drag a group, all contained components move with it as a unit.

Customization

From the group editor (double-click a group):

Label - Displayed centered above the group box
Color - Choose from 8 preset colors
Line style - Solid, dashed, or dotted border

Resizing

When a group is selected (or the group tool is active), all four corners become resize zones. Drag any corner to resize the group in that direction.

Group metrics

After running a simulation, each group displays aggregated metrics for its members:

in - Total packets received by components in the group
out - Total packets sent out by components in the group
drop - Total packets dropped (shown only if drops occurred)
util - Average utilization across all group members

On the canvas, metrics appear as subtle text in the top-right corner of expanded groups or below collapsed groups.

In the sidebar Overview panel, each group card shows a 4-column grid with labeled metrics: Received, Sent, Dropped, and Util.

Collapse and expand

Groups can be collapsed to hide their internal components and simplify the view:

Click the - button next to the group label to collapse
Click the + button on a collapsed group to expand
Right-click a group and choose Collapse group or Expand group

When collapsed:

Member components are hidden from the canvas
External connections are rerouted to the collapsed group node
Internal connections (both endpoints inside the group) are hidden
The group renders as a compact labeled node

This is useful for managing complexity in large systems. Collapse subsystems you are not actively editing.

Group templates

You can save a group as a reusable template and insert it later:

Save - Right-click a group and choose Save as template. The group, its member components, and their internal connections are stored.
Insert - Right-click empty canvas space and choose Insert group template. A picker shows all saved templates. Click one to place it on the canvas with fresh component IDs.
Delete - In the template picker, hover over a template and click the trash icon to remove it.

Templates are stored in your browser’s local storage.

A/B comparison

When a simulation baseline is captured (via the Stress Test panel), per-group metrics are also saved. After re-running the simulation, the sidebar shows delta values for each group comparing current results to the baseline:

In delta (green = more received, red = less)
Drops delta (green = fewer drops, red = more)
Util delta (green = higher utilization, red = lower)

This helps you evaluate the impact of changes on specific subsystems.

The Overview panel organizes components by group membership:

Groups section lists each group with a colored dot, label, and member count
Click a group row to select it on the canvas
Member components are listed inside each group card
Ungrouped components appear in a separate section below

Drawings

Use the Draw tool (D key) to sketch freehand annotations directly on the canvas. Drawings are purely visual and do not affect simulation.