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Atmospheric Scattering Fog + Blur Masking - FILES
🕑 Added 2021-03-08 11:35:27 +0000 UTCHere's a maskable blur effect that you can use in a variety of ways. It's done the same way the blur on the refractive rain shader (from here https://www.patreon.com/posts/rain-shader-with-32056295), by using a Command Buffer to grab the screen every frame, blur it, and then write it out as a global texture that can then be sampled in our shaders.
All the important components for this effect live on the Main Camera (found in the hierarchy under the Player Capsule -> Camera Pivot -> Main Camera), the most important one being the CommandBufferBlurCameraHDR.cs component, which adds the Command Buffer to the camera. This is also where you can control the strength of the blur, by adjusting the Blur Steps, and Blur Scale. Additional Blur Steps require more passes through the shader, but creates a higher quality blurring effect.
Command Buffers are very useful. You basically set them up once at the start, attach them to a camera or light, and then they execute any series of commands you've stored in them, such as grabbing the screen, blurring it, then setting it as a global texture. You can read more about them here.
In the gif above, the blurred texture is used in two places - both in the ground fog (from the interactive environment asset here https://www.patreon.com/posts/environment-47408016), and also it's masked in using the screen depth, combined with a fog colour, to create an Atmospheric Scattering effect of the distance fog. It's kind of a depth of field + fog combo. This distance fog is done with the PostProcessExample.cs script, using the BlurryFog material. It was a very quickly thrown together distance fog just to show how the render texture can be used, and could be improved greatly.
The scene from the above gif is Assets\Masked Blur\GroundFogBlurred.unity
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But we can also arbitrarily mask where we want the blur to occur!
It's possible to mask this blur by another screenspace texture or render texture. In the included example, I've used replacement shaders to render out a separate mask (a black and white image to define where the blur occurs) of only the areas effected by point lights, shown in the above gif.
This scene is Assets\Masked Blur\PointLightMaskedBlur.unity
You'll notice that the Main Camera also has a PointLightShaderReplacement.cs component on it. This creates a child camera which renders out the mask (at a downsampled resolution) via Shader Replacement, which basically renders the scene again, but with all the shaders replaced for the one we specify by the "Mask Replacement Shader". At the moment it's using a PointLightMask.shader which you can see just renders everything black except for the point light's light attenuation.
Here's a screenshot, with the point light mask shown as an inset (inverted, so that everything white is blurred, everything black remains in focus)
You'll notice the PostProcessExample.cs on the Main Camera now uses the Masked Blur material, instead of the Blurry Fog material. This material reads from the mask render texture (created via Shader Replacement) in order to mask the blur render texture (created via Command Buffers). Lots of render textures going around!
You aren't limited to masking via point light attenuation, you could also use textures, world space noises, or perhaps even other image effects. You could blur certain enemies, or anything that isn't the main character, or confine the blur to the sky or ground or fire particles etc. The imagination runs wild.
And it's not just something you should consider using with the blur effect - masking any image effects is a very useful thing to be able to do, and Shader Replacement can be a decent way to approach it. You can read more about Shader Replacement in the official docs. If you're using other different render types, such as alpha cutout or transparent, you'll need to create your own replacement shaders for them to also show up in the mask. As long as the render types match and fields line up ("_MainTex") for example, then everything should just work.*
*haha except Unity, so who knows... Good luck!
If anything doesn't work, is confusing, or you just need help setting anything up, let me know in the comments or on discord and I'll do what I can to help talk you through it. That's what I'm here for!
I hope this remains helpful to you. Thanks again for all the support.
