What is a shader?

A shader is a collection of instructions for pixels on your screen, that help you render a scene, they are used for detailing surfaces, adding textures and they help to develop the look of materials in your scene.

Through their coding language, shaders transform dull and dreary environments that may have lacked a cohesive look to staggeringly beautiful works of art.

There are two types of shaders vertex shaders and pixel shaders

Vertex shader

A vertex shader is a graphics processing function, which manipulates vertex data values on an X (length), Y (height) and Z (depth) 3D plane through mathematical operations on an object. These variations range anywhere from differences in color, texture coordinates, orientations in space, fog (how dense it may appear at a certain elevation) and point size.

Pixel shader

A pixel shader is a small program which processes pixels and executes on the Graphics Processing Unit

When you create a pixel shader, you've created a fragment processing function which manipulates fragment data. Pixel shaders often have to be "driven" by the vertex shader. For example to calculate per-pixel lighting the pixel shader needs the orientation of the triangle, the orientation of the light vector and in some cases the orientation of the view vector.

If you want to see exaples of shaders I have created you can look at my tarnished glass shader in my profile

The shader editor in Blender

The Shader Editor is used to edit materials which are used for rendering. Materials used by Cycles and Eevee are defined using a node tree. Therefore, the main window of the Shader editor is a node editor.

There are a few types of shaders available as nodes:

BSDF shader

Describe light reflection, refraction and absorption at an object surface.

Emission shader

Describe light emission at an object surface or in a volume.

Volume shader

Describe light scattering inside a volume.

Background shader

Describe light emission from the environment.

Each shader node has a color input, and outputs a shader. These can then be mixed and added together using Mix and Add Shader nodes. No other operations are permitted. The resulting output can then be used by the renderer to compute all light interactions, for direct lighting or global illumination.

Blender has various built in procedural texture nodes, with texture coordinates and various parameters as input, and a color or value as output. No texture data-blocks are needed; instead node groups can be used for reusing texture setups.

There are different types of nodes in blender, each one of them has a library of nodes for data inputs and outputs, for example there's the vector node, color nodes, converter nodes, etc.

I will talk abouth them later in future post, meanwhile you can grab my shader nodes for free in my profile and experiment with the node setups.

I hope you find this article helpful if you're starting out in blender or another 3d software, see you in the next blog post :)

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