===== Using HDRI image in Actif3D =====
 
An HDRI, which stands for High Dynamic Range Image, is a 360° image that is wrapped around our 3D scene for lighting and background purposes.

For example, it allows you replace the default sky with a sky texture that surrounds the scene.

Firstly, please open the HDRI tab in Actif3D Editor. 

{{:wiki:hdri.jpg}}


==== HDRI texture ====
Imported the HDRI texture with the button at the **HDRI texture**.

{{:wiki:hdri-samples.jpg}}
> The HDRI texture should be a 360 x 180° equirectangular panorama, otherwise it will have visible stitches. You can also directly use an HDR or EXR file downloaded from some internet source like https://polyhaven.com/hdris

=== Rotation ===

The rotation of the sky texture relative to the scene.

==== Fog ====
These settings apply fog to the scene and control the fog parameters.

 
=== Distance fog ===
Enable exponential distance fog that will affect objects based on distance from the camera.

  * Density - controls the density of the fog. The higher the value, the thicker the fog.
  * Start - define how far from the camera the fog effect should start.
 
=== Height fog ===

Enable exponential height fog, which affects objects based on their position on the Z-axis.

  * Density - controls the density of the fog. The higher the value, the thicker the fog.
  * Level - set the position on the Z-axis where the fog should start.
 
==== Color ====

Specify the colour of the fog - this applies to both distance fog and altitude fog.