IES Cookie Importer

The IES Cookie Importer converts .ies photometric files into light cookie textures. These textures can be used to approximate real-world light distribution patterns from IES lighting profiles.

IES files describe measured light intensity at different angles. The importer samples that data and bakes it into an image that can be used as a projected cookie texture for lights.

Open it from the World Editor window menu under Experimental > IES Cookie Importer (WIP).

Files

Use the Files section to select an input .ies file. The tool infers an output image path from the input file and writes a .color.png cookie texture.

Available actions:

Browse: selects an input .ies file.
Read IES Info: parses the file and displays metadata without generating output.
Generate Cookie: generates the output cookie texture.
Open Output Location: opens the folder containing the generated image.

By default, the input path starts under /art/special/ies/. Keeping source .ies files and generated cookies in a predictable art folder makes it easier to update or regenerate them later.

The output path is derived from the input file name. For example, an input .ies file will normally produce a matching .color.png file. The tool also writes metadata next to the output when supported by the importer.

IES Information

After reading an IES file, the tool displays header metadata and photometric data such as the IES version, photometric type, units, lamp data, angle counts, and candela range.

Use this information to confirm that the selected file is valid before generating the cookie.

Important fields to check:

Photometric type: indicates how the angular data should be interpreted.
Units: shows whether dimensions are stored in feet or meters.
Vertical and horizontal angle counts: higher counts usually mean more detailed source data.
Candela range: shows the minimum and maximum intensity values found in the profile.

If the file reads successfully but the generated cookie looks wrong, check whether the source profile uses an unexpected photometric type or very narrow beam angles.

Cookie Settings

The Cookie settings control how the IES profile is projected into the texture:

Resolution: output texture size, using power-of-two values.
Projection: chooses between perspective and linear projection.
Rotate: rotates the generated cookie.
Auto angle from IES: derives the cone half-angle from the IES data.
Manual half-angle: used when auto angle is disabled.
Auto-center on brightest direction: centers the cookie on the brightest sampled direction.
Center theta / Center phi: manual center direction when auto-center is disabled.
Edge feather: softens the outer edge of the cookie.

The Use Peak Direction and Auto-Center actions help align the cookie around the strongest part of the light distribution.

Use Auto angle from IES for most profiles. Disable it only when you need a specific cone angle for art direction or when the source file contains a wider angular range than the in-game light should use.

Use Auto-center on brightest direction when the brightest part of the profile is off-axis. For symmetric downlights this may not make a visible difference, but it can help with asymmetric wall washers or fixtures that intentionally throw light to one side.

Use Edge feather when the cookie has a harsh edge after projection. A small feather value can hide sampling artifacts at the outer edge of the cone.

Output Settings

The Output settings adjust the generated image:

Percentile: clamps the brightest values before normalization.
Gamma: changes the image response. 1.0 is linear; higher values can be useful for previewing.
Scale: scales the output intensity.
Invert: inverts the cookie image.
Reset Settings To Defaults: restores the default import settings.

The Percentile control is useful when a small number of extremely bright samples make the rest of the cookie too dark. Lowering it slightly can preserve more visible detail in the generated texture.

Use Gamma mainly for preview and artistic adjustment. A linear value of 1.0 keeps the generated intensity closer to the sampled data. Higher values can make midtones easier to see.

Use Scale to brighten or dim the generated output before it is written. This is separate from the final light intensity set on the light object.

Preview

After generation, the Preview section displays the output cookie image if it exists and can be loaded. If the preview fails, check that the output path exists and that the texture was generated successfully.

Basic Workflow

Place the .ies file in an art folder, such as /art/special/ies/.
Open IES Cookie Importer (WIP).
Click Browse and select the .ies file.
Click Read IES Info and check the metadata.
Keep the default settings for a first pass.
Click Generate Cookie.
Review the preview image.
Adjust projection, center, percentile, gamma, or scale if needed.
Use the generated .color.png as the light cookie texture.

Troubleshooting

If Read IES Info fails, confirm the path points to a valid .ies file and that the file is available through the game filesystem.
If the output image does not appear, check whether the output folder exists and whether the game can write to it.
If the preview is black or nearly black, try lowering Percentile, increasing Scale, or checking the candela range in the source file.
If the brightest area is off-center, enable Auto-center on brightest direction or use Use Peak Direction.
If the cookie appears rotated incorrectly, adjust Rotate and regenerate.