The emissive component of an HDRP decal projector does not affect terrain

Setup as follows:

  • Default cube to receive the decal projection.
  • Standard HDRP terrain to receive the decal projection.
  • Simple decal shader with base color and emissive outputs.

As you can see in the screenshot, the emissive element of the decal projector correctly highlights the cube, but not the HDRP terrain.

(Core problem: we need to do some “unlit” area-of-effect projections on terrain that looks the same no matter if it’s night, day or whatever angle the sun is coming from. This will require the terrain not to ignore the emissive element of the decal projector.)

Any idea? Thanks!

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Hah! I have just submitted this as a bug report. Could you try to disable either Decal Layers or Light Layers from your HDRP Asset and post the results here?

Well well well… the result is with Decal Layers disabled in the HDRP Asset, the terrain suddenly receives emissive from the decal projector.

Do you mind dropping your bug report link here somewhere? Or possibly let me know if/when the official bug page goes up (which is different from the initial report page).

That’s what I thought. This is the same case as mine - disabling either decal or light layers feature in HDRP will result in correct emission rendering from projected decal onto the terrain.

Sure, I’ll post it here when it will reach the issuetracker. Right now I have only the confirmation email with that internal id.

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My bug report got verified so the issuetracker link is here: Unity Issue Tracker - [HDRP] Emissive decal doesn't show in terrain when the Decal Layer and Light Layer are enabled in the HDRP Asset

it seems that it is fixed in 15.0.0 so let’s hope for quick backports.

ping @mgeorgedeveloper_1 as requested

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Where do I find the Decal Layers and Light Layers to disable? In the HDRenderPipelineAsset asset? Sorry I’m a bit new to Unity

Still an issue in Unity 6 HDRP version 17, decal emission is not working on terrain if decal or light layers are enabled.