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# Fading Between Multiple Materials on a Single Mesh

Hi All,

Please forgive another newbie question. I have a static mesh that I want to be able to change the material on by fading from material A to material B to material C, what would be the best approach to do that? The transition would take place at specific frames on the level sequence actor.

I tried to use a layered material but I couldn’t seem to figure out how to use a constant or a scalar parameter to drive the alpha of the materials to make them appear and disappear. I also understand that the layered material approach is computationally expensive so maybe it’s not the best approach for realtime use. I tried another approach for switching materials but it was a hard transition, no fade. Currently I am using 3 identical static meshes (simple planes), each with their own material, then I animate the opacity of each material to fade them in and out.

Any help would be greatly appreciated, thanks in advance.

That is a far worse idea then having it all contained in one material. With that solution, you’ll be able to see through the mesh, and there will be terrible Z-fighting.

It’s an odd thing to try to make, but I would try to aim for having it all contained in one material.
You’ll need to use my favorite material node of all time: Lerp (Linear Interpolate). Lerp gives a linear blend between two Scalars, V2s, V3s, or V4s. It’s very convenient.

Here are some examples of the usage of Lerp:

• A = 0, B = 1, Alpha = 0.5. Result: 0.5
• A = 5, B = 10, Alpha = 0.1. Result: 5.5
• A = 3, B = 7, Alpha = 0. Result: 3
• A = 3. B = 7, Alpha = 1. Result: 7

So Alpha is just the percentage that the Result will be B rather than A.

Hope this helps!

Thanks @NachoMonkey2. I have slightly offset the 3 meshes to prevent Z fighting, but I would still like to find a more elegant solution. Can you expand on the above at all? I should also mention that there are 3 materials, and that they are media elements. I am currently working with 2 video files and 1 NDI feed but eventually it could be 3 live video feeds, although at that point it would likely be an upstream switcher that would handle the switch between feeds.

I have created 3 Material Functions, each with their own attributes and I have tried feeding the first two into a Material with a MatLayerBlend_Simple and I have connected a Constant to the Alpha pin but I can’t seem to get the Top Material to display. I have also tried creating the 3 material networks inside the Material using MakeMaterialAttributes and then feed the first two into a MatLayerBlend_Simple and connect a Constant to the Alpha pin. This seems to work for two, but as soon as I add a third, by either adding another MatLayerBlend_Simple on the output of the first MatLayerBlend_Simple or by using the MatLayerBlend_TenLayerBlend, I can’t get the third Material to appear.

You’ll want to use dynamic material instances as shown on the following page:

Thanks @pookemon. It ended up being much easier than I realised. Instead of having three materials and switching between them, I used 3 textures inside one material and then user LERP to switch between them.