Stacking Order

When multiple cues overlap on the same display area, WATCHOUT determines which content appears in front. Stacking order controls this at the cue level and the timeline level.

Per-Cue Stacking Mode

Every media cue has a Stacking property in the Cue Properties panel, under the Presentation section. It has two modes:

By Layer

The default mode. Cues composite by their layer order within the timeline. The Z position has no effect on stacking. Use By Layer for most 2D content, where the layer arrangement should decide what appears in front.

By Z

Cues composite by their Z position (depth). Use By Z for 3D scenes where depth order should decide visibility, such as projection mapping onto 3D models.

Mix stacking modes within one timeline. The renderer applies each cue's own Stacking mode.

Per-Timeline Stacking Order

Timelines also have a Stacking property in the Timeline Properties panel, under General. It has two options:

Timeline Order

The default setting. Timelines render in their order in the Timelines panel. Drag timelines in the panel to reorder them.

Always on Top

A timeline set to Always on Top renders above all timelines that use Timeline Order, regardless of its panel position. Use this for overlay timelines such as a logo or emergency-messaging layer.

Layer Order Within Timelines

Within a single timeline, the layer arrangement sets the rendering priority for cues using By Layer stacking. Layers are numbered from the top of the Timeline window, starting at Layer 1. The topmost layer is the frontmost visual layer; lower layers render further behind.

Cross-Timeline Compositing

When multiple timelines contribute content to the same display area:

  1. Always on Top timelines render in front of all Timeline Order timelines
  2. Timeline Order timelines render in their Timelines-panel order

Within each timeline, cues composite by their per-cue stacking mode (By Layer or By Z). Each timeline's result is then layered by the timeline stacking order.

Practical Implications

Blend modes and transparency. Stacking order affects how blend modes (Add, Multiply, Screen) interact between overlapping cues. A cue with the Add blend mode adds its pixels to the content below it. Changing the stacking order changes what is below the blended cue.

Opacity and fade effects. When a cue fades to transparent, the content behind it becomes visible. Incorrect stacking shows unexpected content during fades.

Multi-timeline shows. Use Always on Top only for true overlay layers (emergency messages, persistent logos). Rely on panel ordering for the main content timelines.

Previous Next