<p>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.</p>

CC BY-SA 4.0
2021-05-29T06:15:37.840Z
2021-05-29T06:15:37.840Z
Felipe Gutierrez
<p>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:</p>
<p><img src="https://i.sstatic.net/SkTl5.jpg" alt="enter image description here" /></p>
<p>For an example of what this looks like in a modern game engine, check out <a href="https://docs.unrealengine.com/en-US/RenderingAndGraphics/Materials/HowTo/Refraction/index.html" rel="noreferrer">Unreal’s documentation</a>.</p>

CC BY-SA 4.0
2021-05-24T18:03:56.687Z
2021-05-24T18:03:56.687Z
Noah Witherspoon
<p>I was watching this trailer:
<a href="https://www.youtube.com/watch?v=pWh5388AEHw" rel="nofollow noreferrer">https://www.youtube.com/watch?v=pWh5388AEHw</a></p>
<p>and at 1:22, the player used a magic trick that created a sphere that warped the projection of the scene.
<a href="https://i.sstatic.net/vUcJ1.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/vUcJ1.png" alt="" /></a></p>
<p>Does anyone know what is this effect?</p>

<transformations><projections>
What is this graphical effect called?
user1584421
# What is this graphical effect called?

(Asked by: username_0 on 2021-05-24)

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.
[![](https://i.sstatic.net/vUcJ1.png)](https://i.sstatic.net/vUcJ1.png)

Does anyone know what is this effect?

**Tags:** transformations, projections


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## 2 answers

### Answer by username_2 on 2021-05-24. Score: 5 | Accepted answer

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](https://i.sstatic.net/SkTl5.jpg)

For an example of what this looks like in a modern game engine, check out [Unreal’s documentation](https://docs.unrealengine.com/en-US/RenderingAndGraphics/Materials/HowTo/Refraction/index.html).


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### Answer by username_1 on 2021-05-29. Score: 3

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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