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This group of attributes allows the material to be changed depending on the type of ray. For example, an object can be rendered with one material when looked directly from the camera, and with another material, when looked in reflections.

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UI Paths

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base_mtl – Specifies the material V-Ray will use uses while rendering the object.

gi_mtl – Specifies the material V-Ray will use uses while calculating the GI solution.

reflect_mtl – The material V-Ray will use uses to render the object with, when the object is seen in reflections. For more information, see Using the Reflect material example below.

refract_mtl – The material V-Ray will use uses to render the object with, when the object is seen in refractions. For more information, see Using the Refract material example below.

shadow_mtl – The material that will be is used to render shadows cast from the object.

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Enable the GI material – Enables the rendering of the material connected to the gi_mtl input of the node. 

 Enable the Reflection material – Enables the rendering of the material connected to the reflect_mtl input of the node.

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This example shows how the use of a GI material will affect affects the rendering.

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This material contains in itself the initial 2 V-Ray materials - the floor's and the walls' ones. So now assigned on the floor object, V-Ray will know knows that while calculating the GI it has to use the GI material (in our case: walls - VRayMtl with Diffuse Color (200, 200, 200)) and during rendering it will use uses the Base material (in our case: floor - VrayMtl with texture in the Diffuse Slot). The result of that is quite different from the previous render as the Color Bleeding has gone. Of course this depends entirely on our choice for the GI material. For instance, if we had chosen a bluish colored material, the final result would also be tinted slightly to blue, like in the first render with the pale brown colors.

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The next render is even more complex as the VRayOverride Refract material of the boxes is activated as well. From left to right follow: a cyan, a purple and a yellow diffuse color. Those materials are set so that when seen through refraction, V-Ray will consider considers and render renders the objects with them. As you can see the Reflect materials are still affecting the render image. If you take a closer look at the lens' edges you will notice the green reflection, which is actually the that reflect material of the middle boxes. While V-Ray had been tracing the rays on the lens' surfaces, those polygons on the edges had first captured a reflection, so that's why there are green traces.

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