Eye/Iris Dilation & Constriction in Unreal Engine 3

A few days earlier I said I wanted to experiment with UV animation. Here it is!

The diffuse and specular textures are made by V8matey. I got his files from here.

It’s a simple shader that simulates the reaction of our eyes to the light. When there’s more light, the iris shrinks to block out much of the light. If there’s less light, the iris increases to allow more light go into the eye. My initial intention was to play around with UVs so I didn’t put much effort on making it a real eye shader, which potentially needs more instructions to make it look flesh, and human.

The amount of light going into the eye is simulated by taking the dot product of the eye surface and the light vector. Here I don’t have an accurate normal map, so I just use the geometry normal which is (0, 0, 1) in tangent space. Also the other important part is a mask of iris. You can make one in texture but in my opinion, making one with texture coordinate node saves more memories and doesn’t take much computing power.

This is fun. I think I need to spend more time reading computer graphics books to better use the Material Editor.

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