I was watching this trailer: https://www.youtube.com/watch?v=pWh5388AEHw

and at 1:22, the player used a magic trick that created a sphere that warped the projection of the scene.

Does anyone know what is this effect?


2 Answers 2


I don’t think there’s a formally established name for it, but it’s generally known as distortion, warping, or refraction. It works by taking an already rendered version of the current frame, sampling it with warped/stretched texture coordinates, and, usually, compositing the result back in with the rest of the scene. One of the first games I know of that used it was Half-Life 2, for an effect when the Strider enemies fired their cannon:

enter image description here

For an example of what this looks like in a modern game engine, check out Unreal’s documentation.


Rasterizers will probably handle it as a post processing effect. While doing ray tracing/marching it's possible to bend the rays while incrementing at each step.


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