Making a fullscreen box blur
Up until now, we’ve seen how to implement some screen effect shaders thanks to the URP Sample Buffer node, and we’ve played around with the original render image in various ways. In this last section, we’re going to discuss another method for creating fullscreen shaders with the Shader Graph tool and apply it to a box blur filter effect.
We will start by getting a quick reminder of how the box blur effect works; then, we’ll see how to implement it thanks to a Sub Graph asset; and finally, we’ll re-integrate this Sub Graph into a fullscreen URP shader to apply our box blur filter to the whole render.
What is a box blur?
The box blur is a very simple low-pass filter that lets us easily blur an image thanks to a few mathematical operations. It relies on a basic idea, which is to replace the initial value of each pixel in the image with the average of their neighbor pixel values.
This technique is far from perfect...
