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I am trying to implement some of the tips in this lookdev article, and the first thing I tried is "noising up" my spotlights with a cookie.

I have figured out that all you really have to do is add a texture to a light. But what I don't understand is how to noise it up without altering the light color. What is the normal setting for light cookies that add slight intensity variation to a light? Am I supposed to just set the color to grey? Or is color supposed to be off and RGB-to-intensity chosen? That only seems to work with colored noise. Lastly, I assume it is like Ambient Occlusion where you want to darken with the multiply mode but I can't find tutorials either way. Any help is appreciated!

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  • $\begingroup$ related: blender.stackexchange.com/questions/6298/… and blender.stackexchange.com/questions/12218/… $\endgroup$ – user1853 Jun 7 '16 at 20:35
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    $\begingroup$ Possible duplicate of How do I properly set up a spotlight cone? $\endgroup$ – user1853 Sep 23 '17 at 14:32
  • $\begingroup$ Light doesn't multiply in a scene it adds. So any cookies or gobos or flags simply occlude the light so it won't be added there. Remember that "shade" is not a "thing" but an absence of light. You make shadows by removing the light from that place. Texturing light is usually a cheap way to filter the wavelength of the source, normally you would shoot light through glass etc which takes more processing time. Also BI should be slower with ray casting when sending light past geometry so this should be the fastest way to generate the effect. $\endgroup$ – 3pointedit Jul 25 '18 at 22:54
  • $\begingroup$ The BI lamp does allow you to alter the texture of the shadow which is physically implausible but hey, whatever. You must have the lamp in Add mode, to affect the shadow. $\endgroup$ – 3pointedit Jul 25 '18 at 23:03
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The easiest way would be to put a sub-divided mesh in front of your light, with a multi-slot material bank associated to that mesh. Then all you would have to do in each material slot is give each their own alpha value, then do a random face selection for each slot and assign it to the selection.

Just make sure that your material is equally RGB (R=G=B) for each slot, and you won't modify the color, only the tint/intensity.

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To alter the Blender Internal lamp you need to add a texture then turn on Color in the influence tab of the properties panel.

lamp texture

Then change the Default mix color to white (default is pink). And make the mix type Add this last bit is really important, remember that light is additive to the scene, well so is the texture. Other mix types don't seem to affect the lamp.

lamp material

Notice that the lamp may look washed out due to the texture being added to the base color of the lamp. Don't reduce the lamp energy, rather change the lamp color to black. Then the texture will be added to a zero lamp color.

Change the texture coordinates to Object and select the lamp, then the texture will follow your lamp around. Bear in mind that the texture is mapped to a cube shape around the lamp, even if the lamp is a point source.

Finally the texture does not contribute to the Halo cone effect, so you can't get crepuscular (god) rays this way.

texture light

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