How can you use color ramp to affect emissive shader

Is it possible to affect the emissive shader with the color ramp at all? I would like to do something like this (image below): • if you plug the ColorRamp into the Emission node it will affect it, but maybe give more details of what you want to do Jul 16 '19 at 17:06
• how do you want to effect the emissive shader? Jul 16 '19 at 18:13
• made an edit to show what i mean Jul 16 '19 at 18:21

You could use the supplied Gradient node, mapped appropriately.. Here, just using the Generated texture space on a plain mesh circle.. (it could be a sphere, if you want it to be) The Mapping node rotates the gradient to the right orientation, the Color Ramp converts the input 0-1 value to a range of colors. (With a bit of Glare added in the compositor to simulate the reference)

That can be done using the geometry input node and doing that you'll have to tune the Z value depending on the object geometry: The node math is done this way, as in this example Z is going from -1 to +1. So dividing by 2 obtains something between -0.5 and +0.5 and add 0.5 obtains something between 0 and 1 which is what we want for the colorramp.

You can also use a UV map (to avoid geometric calculation). For instance make the UV map with 'project from view (bounds)', so that you can: • thank you that's exactly what i needed. I don't fully understand why the math node is used in this way but if it works it works ¯_(ツ)_/¯ Jul 16 '19 at 18:54
• I've added some explanation about the math. Jul 16 '19 at 18:59