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The closest I can get to making mesh lights affect their environment in Blender Eevee is giving them an Emission material and turning on "Bloom". But this isn't emitting proper light, it just looks like it is, but it doesn't light the surroundings whatsoever.

enter image description here

I would like to be able to light a scene with meshes without having to put point lamps everywhere just to make them emit light.

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Mesh lights can be used with EEVEE but they require an extra step to work: baking indirect light.

  • Here is a scene with a Light-type object (correctly lighting a receiver plane) and two Emission meshes (currently doing nothing)

    enter image description here

  • We should add an Irradiance Volume object, and make it encompass the volume that is affected by the light that we want to capture. This object has a Resolution option that should be adjusted depending on needs: the finer the grid, the most spatially accurate the description of the light in the scene.

    enter image description here

  • To finish, in the Scene properties, under Indirect Lighting, we must hit "Bake Indirect Lighting". This will compute how much diffuse light is bouncing around each one of the "dots" of the Irradiance grid.

    enter image description here

    Now the mesh lights are contributing to the lighting in the scene! Moreover, once the lighting is baked (and if the lights are not moved), objects can still be moved around and will be correctly lit by the baked light (they won't cast shadows though!):

    enter image description here

As far as I know, the Indirect Light cache doesn't have frames so the animation of mesh lights isn't possible at the moment.

In the manual: Irradiance Volumes - Indirect Lighting Cache

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  • $\begingroup$ One of the things that I most direly wanted to learn about Eevee. Hope they make it real-time some day. $\endgroup$
    – dotNET
    Commented May 8, 2019 at 15:47
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    $\begingroup$ Would it be possible to trigger the light baking from python on specific frames? (if the light changes position or intensity) $\endgroup$
    – aBe
    Commented Aug 16, 2019 at 19:10
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    $\begingroup$ for moved objects to cast shadows the lights need to be re-baked or these lights produce no shadow at all? $\endgroup$
    – Luciano
    Commented Jun 10, 2020 at 8:27
  • $\begingroup$ They need to be re-baked $\endgroup$
    – Nicola Sap
    Commented Jun 10, 2020 at 10:03

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