Unity Shader Basics

Textures & UVs

• Textures can be made using all types of software: Ps, Affinity, Aesprite etc.
• UV co-ords are attached data that act as a mapping between the vertices of the mesh and texture position.
  • Setting up the UVs on custom objects has to be done manually.
• Adding time nodes can help with animating shaders (e.g scrolling textures).

Transparency and Alpha

• Because of the way transparent shaders are rendered, Unity has a rendering queue system for objects.
  • Using code shaders requires a manually queue number.
• Alpha (in RGBA) means transparency.
• Alpha clipping allows us to set an alpha threshold – any pixels below it are culled.

Vertex Shaders

• Meshes are made of vertices – each frame, Unity needs to read the vertex data and figure out where to show vertexes on the screen.
• In shadergraph, we have some control over these vertex shader stage, and can move them around.
• Tesselation is the ability to create new vertices between existing ones before running the vertex shader.
  • To implement, tick ‘Tesselation’ in the Graph settings, which adds 2 new output blocks.
• Object space: abstract mesh data where vertex points are defined relative to the mesh origin point
• World space: where vertex positions are relative to the world origin.
• Clip space: where vertex positions are relative to the camera position.

Depth Buffer & Silhouettes

• Depth buffer (also known as the ‘Z-Buffer’) stores values registering how close objects are to the camera.
• Depth testing: when something is rendered, we calculate the depth value of what is being drawn and compare it with the buffer.
  • If the object has a lower or equal value, the new object is drawn over the existing one.
• To create silhouettes, enable depth textures in the URP. Create a seperate shader, change the ‘surface’ to transparent, and create a foreground and background colour(s).
  • Add the ‘scene depth’ node and set its sampling to Linear01. create a LERP block, attach the nodes and attach all to the Base Colour.