Fake reflections in Cycles

Question

Is it possible to fake reflections per object in Cycles? If so, how? (I don't mean one image to appear as background and another to appear in all reflections). I mean using an image on the object mapped to reflection coordinates.

Scenario: I am using an Environment texture in the world shader settings. I have multiple objects each with reflective surfaces, one of which is using the Glass shader, I'd like the glass to reflect as it normally does with the addition of another image. To be able to blend the actual scene (objects+environment maps) with an entirely different environment reflection that isn't part of the scene.

Answer 1

Expanding on brecht's answer, here is a simple node setup:

A glossy node is used instead of an Emission node to get the "real" reflections in addition to the image. To do this with a Glass node, you will have to separate the glossy and refraction.

Answer 2

First you need to render an environment map of the reflected scene:

• Put the camera in the center of the scene
• Change it to Panoramic and set the type to Equirectangular
• Render and save image

To use this image in an object material:

• Add an Emission node
• Plug an Environment Texture node into its color
• Plug Reflection texture coordinates into the texture node

Answer 3

You could render each object in the scene separately, then combine them in the compositor. For each render set the enviroment to the desired map.