An Introduction to Shader Programming

in Unity

A MEF Training Presentation - 2016

Graphics Hardware

Central Processor

CPUMemory

Graphics Processor

GPUMemory

Frame Buffer

Its Programmable Hardware!

OpenGLAPI

GLSLPrograms

CgPrograms (Nvidia)

Khronos Group

EGLAPI

Vendor Specific

Fixed Functions

*Microsoft equivalentis DirectX and HLSL (Similar to Cg)

Well some parts areprogrammable & others can be

configured with fixed function calls

OpenGLAPI

OpenGL Pipeline

Vertex Buffer Objects

VertexShader

PrimitiveAssembly Rasterization

TextureMemory

FragmentShader

FragmentOperations Frame Buffer

EGLAPI

Vertex Buffer Objects

You store Vertex properties in these:

Positions,Texture Coordinates,

and so on…

OpenGL Pipeline

Vertex Shader

You write a piece of code thatcan change those Vertex properties

Primitive Assembly

Converts the Vertices into primitives and clips shapes that are out of

the camera view

TrianglesLinesPointsetc…

Rasterization

Converts the primitivesinto Fragments(Unborn Pixels)

Texture Memory

You upload Textures into the GPUmemory. These are called Samplers.

Fragment Shader

You write a piece of code thatcolors the fragments.

Fragment Operations

Recap…

OpenGLAPI

OpenGL Pipeline

Vertex Buffer Objects

VertexShader

PrimitiveAssembly Rasterization

TextureMemory

FragmentShader

FragmentOperations Frame Buffer

EGLAPI

Before we dive intocode…

We must gain a basic understandingof the

Model View Projection Matrix!

Models are created in ‘Model Space’ coordinates

But their coordinates transformwhen you put them in

‘World Space’

And coordinates transform onceagain when viewed through

‘Camera Space’

Finally the coordinates transformonce more based on the

‘Projection’

Therefore EVERY vertex hasto go through…

Model Coordinates

World Coordinates

Camera Coordinates

Projection Coordinates

[Model Matrix]

[View Matrix]

[Projection Matrix]

For model vertices to become screen vertices,

we must transform them viacomplex matrix multiplications…

The bad news is that for OpenGLwe have to

calculate the MVP matrix manually…

But Unity makes it very very easy for us

with a built in matrix variable we can use…

UNITY_MATRIX_MVP

UNITY_MATRIX_MVPX

Model Vertex Position=

Screen Ready Position!

Unity makes programminggraphics and shaders

VERY easy…

In order to appreciate that, it isimportant to look at what it takesto render a cube if there was no

Unity…

Fire up Xcode on your MacBooks!

So Unity takes care of all this complexity

plus gives us ShaderLab: Any easyinterface to write shaders with…

OpenGL Pipeline

VertexShader

FragmentShader

ShaderLab

SurfaceShader

ShaderLab is a meta language that

wraps around a Cg program

VertexShader

FragmentShader

ShaderLab

Cg Code

ShaderLabCode

SurfaceShader

A ‘Shader Program’ requires both a

Vertex Shader + Fragment Shader

VertexShader

FragmentShader+ = Shader

Program

Shader Core Inputs & Outputs

VertexShader

Runs for each Vertex

FragmentShader

Runs for each FragmentVertices Fragments

Colored FragmentsUniforms

Let’s get going withwriting Shaders…

Fire up Unity!The rest of this presentation is a hands-on shader writing workshop…