Post-effect parameters

Status: Complete Last Updated: 2026-09-22

Every post effect in the Construct viewport presents its parameters the same way. This page explains the pattern, so the controls feel consistent and so you know where a value goes when you change it.

One pattern for every effect

A post effect declares a list of parameters. Each parameter has a name, a type, a default, and optional bounds and a step. The settings page builds its rows from that list. It does not have a hand-written panel per effect.

This has four consequences:

• A tone mapper with no parameters has no rows of its own. The Tone mapping row in the HDR category is all there is.
• A tone mapper with parameters has its own section under HDR, with one row per parameter, in the order the effect declares them.
• The rows of a tone mapper dim while another tone mapper is chosen. They stay editable, so you can set them before you switch.
• Every row uses the same input for its type. A number gets a drag field with the declared bounds and step.

Where the values live

The selected tone mapper and each parameter value are scene settings. They are saved with the document and follow the settings cascade: the application seed supplies a default for new scenes, the scene stores its own value, and a camera can override the scene.

A parameter value is stored under the effect's identity, as <effect>/<parameter>. Changing the tone mapper does not discard the values of the previous one. Switch back and its parameters are as you left them.

Resetting a value

Each parameter row carries a reset control that returns the value to the effect's declared default. Resetting one parameter does not touch the others.

Effects other than tone mappers

Bloom and exposure use the same declaration. Their rows appear in the same HDR group, above the tone-mapper selector, and follow the same storage rule.

Bloom threshold

A pixel blooms when its brightness after the exposure is above the Bloom threshold. The default is 1: only an over-exposed pixel blooms, such as an emissive surface or a highlight that the tone mapper "none" clips. The threshold follows the exposure. One stop more exposure makes the same pixel twice as bright, so it blooms at half the scene brightness.

Below the threshold no pixel blooms. The bloom effect has a knee parameter for a soft start below the threshold, as a part of the threshold. Its default is 0, no soft start.

A scene that stores its own threshold keeps it. Scenes made before 2026-10-18 often store 0.5, the default of that time, with a soft start of half the threshold, so their bloom started at a brightness of 0.25. Set the threshold to 1 for bloom on over-exposure only.

Thumbnails and the material previews use the default look with bloom on, so that an emissive material glows in them.