June 30, 2021

Unlit Dynamic Decals/Projection

Often when doing VFX you want stuff to stick to the floor. Even when that floor is uneven. Or decals to make existing geometry more interresting, or you want blob shadows on uneven floor, or some other use-cases in the same direction. (note: I used the free “Nature Starter Kit 2” from the Unity Asset store throughout this tutorial) Unity has the concept of a “projector” for that, but I have to admit I dont quite trust them.

June 20, 2021

Polar Coordinates

So far whenever we used coordinates we had a clear grid of 2 or 3 axes in which we could manipulate things and push them around. There were multiple spaces of those like object, world, screen, uv space and maybe more but the base rules were always the same most of the time. That pushing things to the right, pushes them to the right, up is up etc… This is called “cartesian coordinates”.

November 25, 2020

Object Outlines

I have made multiple tutorials about outlines already, doing them with a inverted hull, as a postprocessing effect using the depth and normal buffers or by sampling neighboring pixels of a sprite, but I want to add another technique to those. It uses the same base idea of sampling neighboring pixels as the sprite based one, but can be applied to 3d models. It uses a postprocessing effect, yet can be applied to distinct objects you choose.

September 16, 2020

Graphics.DrawProcedural

The last tutorial was about compute shader basics, how to generate values, read them back to the cpu and use them. One critical aspect in all that is that copying data from the cpu to the gpu (from the ram to the vram) or back takes some time, so wouldn’t it be neat if there was a way to just render the data directly from the GPU without copying it around?

July 26, 2020

Compute Shader

So far we always used shaders to render with a fixed pipeline into textures, but modern graphics card can do way more than just that (sometimes they’re also referred to as GPGPU for “general purpose graphics processing unit” because of that). To do things that arent in the fix pipeline we’re using so far we have to use compute shaders. If you’re asking yourself why we’d do that, the CPU is performant enough, especially once we use multithreading then I’m here to tell you that you’re 100% correct.

July 23, 2020

Sprite Outlines

I already talked about 2 ways of generating outlines in your programs, by analyzing the depth and normals of your scene or by rendering the model twice with a hull. Both of those assume we’re using opaque meshes that write into the depth buffer, if we’re using 2d sprites neither approach works. The approach for this tutorial uses the alpha channel of a texture to generate 2d outlines. Basic Implementation The idea is that we sample the texture at multiple spots around the uv point and remember the biggest value of the alpha channel we find.

February 11, 2020

Instancing and Material Property Blocks

Current State I’m going to go off a basic unlit shader in this tutorial. In all tutorials since that one we always set the properties at a “per material” basis. This allows us to do everything we ever need to do in theory, but depending on the circumstances it might also force us to use tons of different materials. This not only makes a scene harder to author, but can also significantly slow down your game as by default objects with different materials cannot be instanced together and switching drawcalls is one of the main performance sinks of rendering.

January 8, 2020

Inverse Lerp and Remap

In a previous tutorial I explained how the builtin lerp function works. Now I want to add the inverse lerp as well as the remap functions to this. They’re not builtin functions so we’ll have to write our own implementations. While this is a tutorial that focuses on explaining mathematical concepts, they resolve into basic addition and multiplication pretty quickly so I hope it isn’t too hard. Example Shader The base shader is pretty barebones, a little more complex than a completely unlit one.

November 29, 2019

Partial Derivatives (fwidth)

The partial derivative functions ddx, ddy and fwidth are some of the least used hlsl functions and they look quite confusing at first, but I like them a lot and I think they have some straightforward useful use cases so I hope I can explain them to you. Since I’m explaining straightforward functions you don’t have to know a lot of shader programming for this, but you should have a rough overview over how to render simple things with shaders in unity.

October 14, 2019

Handling Depth for Spheretracing

In the last 2 tutorials of the volumetric rendering series I showed how to trace 3d signed distance fields and how to shade the result. In my opinion the biggest drawback of the state of the shader so far is the way that independent objects interact with each other and with regular meshes. They either don’t write to the depth buffer at all, or with the shape of the mesh that’s used for them and the depth check is similarly lacking.