Creating the glow and the bloom effects

In Qt Design Studio, you can add a glow and a bloom effect to your 3D scene using the ExtendedSceneEnvironment component (available in Qt 6.5 and later). With this effect, you can, for example, create glow around illuminated areas (such as material or skyboxes when using image-based lighting) or add ambient light. Using the glow effect is one way to make your scene more realistic.

{An example showing the difference between using a glow effect and not using a glow effect.}

Creating a project with ExtendedSceneEnvironment

To create a project with ExtendedSceneEnvironment as the default scene environment, use the 3D Extended project preset.

For more information about creating projects, see Creating projects.

Adding ExtendedSceneEnvironment to an Existing Project

To add ExtendedSceneEnvironment to an existing project, drag the ExtendedSceneEnvironment component from Components to the 2D or Navigator view.

{The ExtendedSceneEnvironment in the Navigator view.}

Enabling the Glow effect

To enable the glow effect, select SceneEnvironment in the Navigator view and then, in the Properties view, select Enabled in the Glow section.

{The Glow effect properties in the Properties view.}

Note: When setting up or experimenting with the glow effect, use the Replace blend mode to see the effect more clearly.

The Flashlight Example project

The flashlight example used in this documentation is available from the Examples section of the Qt Design Studio Welcome page.

You can use the project to experiment with the Glow properties. When you run the project, you can control most properties with UI controls. Another way to experiment with properties is to change them directly in the Properties view in Qt Design Studio and see the changes live in the 2D view.

{The Flashlight Example project running.}

Basic properties

Usually, the best way to achieve a realistic glow effect in your 3D scene is to adjust the Strength, Intensity, and Bloom properties together.

Strength

Sets the strength of the glow. If this property has a 0 value, the glow effect is disabled. The strength is a scale factor (multiplier) applied per level. This means that with more levels enabled in Blur Levels, a larger strength value has a more pronounced effect.

Intensity

Sets the intensity of the glow. The intensity is effectively a scale factor (multiplier) for the accumulated glow color (including all levels).

Bloom

Sets the overall illumination of the whole scene.

Lower Threshold

Sets the minimum level of brightness for the glow.

Upper Threshold

Sets the maximum level of brightness for the glow.

HDR Scale

Sets how much the glow bleeds (or extends) beyond the borders of bright areas in the scene. The range for this property is 0-8. As seen in the example images below, a high value gives a very modest bleed, while a low number results in a much more visible bleed.

HDR Scale	Example
Bloom disabled
8
1

Blur Levels

Sets which of the blur passes to apply to the glow effect.

The higher the level is, the more the glow effect spreads around the light source, and the softer the glow is.

As seen in the example image below, lower blur levels produce an intense glow within a limited area, while higher blur levels produce a softer glow in a more extensive area. Combine blur levels to get the desired result.

Blur level	Example
1, 2, 3
5, 6, 7
1, 2, 3, 4, 5, 6, 7

Blend modes

The following blend modes are available:

Blend mode	Description	Example
Additive	Often recommended for outdoor scenes with a visible sky or sun.
Screen	Similar to Additive, but the result is less bright.
SoftLight	Often recommended for in-door environments.
Replace	Does not perform any blending, but displays only the contribution the glow effect would blend with the actual content. In practice, this is useful for experimenting and troubleshooting when setting up the glow effect.

Improvement properties

The High Quality and Bicubical Upsampling properties improve the quality of the glow blur by upsampling. Using these properties may slow down the performance of the application. You can also try using the Dithering property in the sceneEnvironment instead. In some cases, Dithering renders a similar result but at a lower cost.

High Quality

Increases the samples used for the glow when downsampling to improve the quality of the glow effect.

Bicubical Upsampling

Reduces the aliasing artifacts and boxing in the glow effect.

Examples

These examples show a zoomed-in image of each effect:

Effect	Example
No effect
High Quality
Bicubic Upsampling

Best practices Examples

Available under certain Qt licenses.
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