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Shaders
Tasos Stamadianos
Before we begin...
- Please download the necessary files:- http://bit.ly/2arPTiv
Agenda
● About me● What’s a shader?● Graphics pipeline high-level● Lighting● Physically-based rendering● Physically-based rendering in Unity● Post-processing effects● Unity shader system● Post-processing effect example
About Me
- Graduated from UOIT- Engine programmer at Ludia- Programming is love, programming is life
No black boxes!
- Know enough to Google it!
Reinvent the wheel!
- Practice, practice, practice to learn!
Ask questions!
- No one attends presentations because they already know everything. - No such thing as a stupid question- While embarrassment can be an effective growing tool for some, it can
paralyze others out of learning.
What’s a shader?
- A lightweight program running thousands at times at once on the GPU- Takes in data and outputs data
- Varies depending on stage of graphics pipeline
Graphics Pipeline High-level
- Starts with a 3D model and ends with a flat image on the screen
Model-friendly vertex data Vertex
Shader
GPU-friendly vertex data
Textures and other data
Fragment Shader
Pretty pixels
Graphics Pipeline High-level
Graphics Pipeline High-level
- Models are comprised of their own points relative to that model, not to your game world
- First step is to position these local points into the game world- To do this we use....
Vertex Shaders
- Given information about a vertex and some info about the world and camera, this places a point on a model into the virtual world
- There’s also some GPU stuff related to clipping but that’s not important for this workshop
- Model data in, important data for shading out!
Graphics Pipeline High-level
- After we know what has to be rendered, it comes time to actually render it- Known as ‘shading’- Use vertex data and some other customizable parameters- Uniforms (constants), textures, etc
Fragment Shader
- The penultimate step of the rendered pixel, but easily the most important- Vertices are assembled into tiny pieces and we use interpolated data to colour
things (normals and UVs most common)- All colouring and effects are done here
- Normal mapping- Colour correction- Toon shading
Fragment Shader
- Most common example is normal mapping
Fragment Shader
- Toon shading is popular too
Fragment Shader
- But nothing is more ubiquitous than LENS FLARES AND BLOOM- SO REALISTIC
The Final Step
- Blending to the backbuffer- Incoming pixels must interact with existing pixels- Try it
Geometry Shaders
- Vertices can also produce more vertices- Geometry shaders take one vertex, do some calculations, and output more
vertices!- Good for particles
Tessellation Shaders
- Take a model as a whole and either reduce/increase the number of triangles- Increases or decreases model quality to save on calculations
Lighting
- Traditional method is to use Phong shading- Looks okay, efficient and cheap- Doesn’t have the next-gen look
Physically-based rendering!
- THE FUTURE IS HERE- Use physical properties of a material (roughness, shininess) to light it, and
reflect how light bounces around a scene!- Global illumination in a fast way- Unity uses this method
Physically-based rendering in Unity
- Unity material system is pretty powerful and customizable- Relies on certain material properties, and we will go over each of them
A Note on Maps
- “Maps” are just fancy terms for textures- Dictate the values at a given point of a surface
- Albedo, specular, normal, etc- Each will be explained
Unity PBR Material Parameters
- Albedo- Colour at a specific point- Can be uniform or provided via ‘albedo map’, AKA ‘texture map’
Unity PBR Material Parameters
- Metallic- One of two shininess options- Basically, how metalic an object is will influence how much light reflects- Can also specify “smoothness”
- Describes how the reflected light will reflect
Unity PBR Material Parameters
- Specular- The other of two shininess options
- Use a map to specify the shiny parts of the
surface- Also uses the “smoothness” parameter
Unity PBR Material Parameters
- Normal map- Specify detailed normals to use in the lighting calculations
Unity PBR Material Parameters
- Height map, or parallax map- Gives the appearance of protruding geometry from a flat surface - Fake extra modelled detail at a fraction of the cost
Unity PBR Material Parameters
- Occlusion map- Specify how certain parts of the model should react to indirect lighting (lighting from the scene)
Unity PBR Material Parameters
- Emission map- Specify the light emitting from areas of a surface- Both colour and intensity
Unity PBR Material Parameters
- Detail mask- Specify parts of the surface which need more detail- Provide more detail with the specified albedo and normal textures
Post-processing effects
- Make things pretty!- Shaders can be used to change colours of a screen as a whole- Known as post-processing effects- Colour correction, greyscale, toon shading, bloom- Lens flares for that next-gen look & feel- Must use the Unity shader and RTT system now
Unity Shader System
- Can write a variety of shaders- Surface shader (lighting, not what we’re interested in)- Traditional vertex/fragment shader (more useful for post-processing)- Fixed-function (i don’t know why these are still here)
Unity Shader System
- We’ll use the Vertex/Fragment shader method- Unity ShaderLab is based on HLSL
Putting it all together
- Need two things:- Script with “OnRenderImage” implemented- Shader to apply
Post-processing effect example
OnRenderImage
- Important parameters- ‘src’ and ‘dest’ are render targets
- One extremely important function
Fullscreen Blur
- One of the easiest effects to create- Can be used to bring things in/out of focus- Cheap DOF
Questions?
Shameless friend plug
- Special thanks to:- Jonathan Virly for the spider mech
- [email protected] Matthew Racanelli for the textures
- mracanelli.com
Helpful resources
- Krita- General 2D painting- https://krita.org/en/
- Blender- 3D Modelling + map painting- https://www.blender.org
- Sculptris- Normal maps- http://pixologic.com/sculptris/
Thank you!
I enjoy learning through teaching!
@tasostamtasosgamedev.com
