OpenGL 4 Shading Language Cookbook

OpenGL 4 Shading Language Cookbook - Third Edition

By : David Wolff

Buy this Book

OpenGL 4 Shading Language Cookbook - Third Edition

By: David Wolff

Buy this Book

Overview of this book

OpenGL 4 Shading Language Cookbook, Third Edition provides easy-to-follow recipes that first walk you through the theory and background behind each technique, and then proceed to showcase and explain the GLSL and OpenGL code needed to implement them. The book begins by familiarizing you with beginner-level topics such as compiling and linking shader programs, saving and loading shader binaries (including SPIR-V), and using an OpenGL function loader library. We then proceed to cover basic lighting and shading effects. After that, you'll learn to use textures, produce shadows, and use geometry and tessellation shaders. Topics such as particle systems, screen-space ambient occlusion, deferred rendering, depth-based tessellation, and physically based rendering will help you tackle advanced topics. OpenGL 4 Shading Language Cookbook, Third Edition also covers advanced topics such as shadow techniques (including the two of the most common techniques: shadow maps and shadow volumes). You will learn how to use noise in shaders and how to use compute shaders. The book provides examples of modern shading techniques that can be used as a starting point for programmers to expand upon to produce modern, interactive, 3D computer-graphics applications.

Title Page

Packt Upsell

Contributors

Preface

Free Chapter

Getting Started with GLSL

Introduction

Using a loading library to access the latest OpenGL functionality

Using GLM for mathematics

Determining the GLSL and OpenGL version

Compiling a shader

Linking a shader program

Saving and loading a shader binary

Loading a SPIR-V shader program

Working with GLSL Programs

Introduction

Sending data to a shader using vertex attributes and vertex buffer objects

Getting a list of active vertex input attributes and locations

Sending data to a shader using uniform variables

Getting a list of active uniform variables

Using uniform blocks and uniform buffer objects

Using program pipelines

Getting debug messages

Building a C++ shader program class

The Basics of GLSL Shaders

Introduction

Diffuse and per-vertex shading with a single point light source

Implementing the Phong reflection model

Using functions in shaders

Implementing two-sided shading

Implementing flat shading

Using subroutines to select shader functionality

Discarding fragments to create a perforated look

Lighting and Shading

Introduction

Shading with multiple positional lights

Shading with a directional light source

Using per-fragment shading for improved realism

The Blinn-Phong reflection model

Simulating a spotlight

Creating a cartoon shading effect

Simulating fog

A physically-based reflection model

Using Textures

Introduction

Applying a 2D texture

Applying multiple textures

Using alpha maps to discard pixels

Using normal maps

Parallax mapping

Steep parallax mapping with self shadowing

Simulating reflection with cube maps

Simulating refraction with cube maps

Applying a projected texture

Rendering to a texture

Using sampler objects

Diffuse image-based lighting

Image Processing and Screen Space Techniques

Introduction

Applying an edge detection filter

Applying a Gaussian blur filter

Implementing HDR lighting with tone mapping

Creating a bloom effect

Using gamma correction to improve image quality

Using multisample anti-aliasing

Using deferred shading

Screen space ambient occlusion

Configuring the depth test

Implementing order-independent transparency

Using Geometry and Tessellation Shaders

Introduction

Point sprites with the geometry shader

Drawing a wireframe on top of a shaded mesh

Drawing silhouette lines using the geometry shader

Tessellating a curve

Tessellating a 2D quad

Tessellating a 3D surface

Tessellating based on depth

Shadows

Introduction

Rendering shadows with shadow maps

Anti-aliasing shadow edges with PCF

Creating soft shadow edges with random sampling

Creating shadows using shadow volumes and the geometry shader

Using Noise in Shaders

Introduction

Creating a noise texture using GLM

Creating a seamless noise texture

Creating a cloud-like effect

Creating a wood-grain effect

Creating a disintegration effect

Creating a paint-spatter effect

Creating a rusted metal effect

Creating a night-vision effect

Particle Systems and Animation

Introduction

Animating a surface with vertex displacement

Creating a particle fountain

Creating a particle system using transform feedback

Creating a particle system using instanced meshes

Simulating fire with particles

Simulating smoke with particles

Using Compute Shaders

Introduction

Implementing a particle simulation with the compute shader

Creating a fractal texture using the compute shader

Using the compute shader for cloth simulation

Implementing an edge detection filter with the compute shader

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Determining the GLSL and OpenGL version

In order to support a wide range of systems, it is essential to be able to query for the supported OpenGL and GLSL version of the current driver. It is quite simple to do so, and there are two main functions involved: glGetString and glGetIntegerv.

Note

Note that these functions must be called after the OpenGL context has been created.

How to do it...

The following code will print the version information to stdout:

const GLubyte *renderer = glGetString( GL_RENDERER ); 
const GLubyte *vendor = glGetString( GL_VENDOR ); 
const GLubyte *version = glGetString( GL_VERSION ); 
const GLubyte *glslVersion = 
       glGetString( GL_SHADING_LANGUAGE_VERSION ); 
 
GLint major, minor; 
glGetIntegerv(GL_MAJOR_VERSION, &major); 
glGetIntegerv(GL_MINOR_VERSION, &minor); 
 
printf("GL Vendor            : %s\n", vendor); 
printf("GL Renderer          : %s\n", renderer); 
printf("GL Version (string)  : %s\n", version); 
printf("GL Version (integer) : %d.%d\n", major, minor); 
printf("GLSL Version         : %s\n", glslVersion);

How it works...

Note that there are two different ways to retrieve the OpenGL version: using glGetString and glGetIntegerv. The former can be useful for providing readable output, but may not be as convenient for programmatically checking the version because of the need to parse the string. The string provided by glGetString(GL_VERSION) should always begin with the major and minor versions separated by a dot, however, the minor version could be followed with a vendor-specific build number. Additionally, the rest of the string can contain additional vendor-specific information and may also include information about the selected profile (see the Introduction section of this chapter). It is important to note that the use of glGetIntegerv to query for version information requires OpenGL 3.0 or greater.

The queries for GL_VENDOR and GL_RENDERER provide additional information about the OpenGL driver. The glGetString(GL_VENDOR) call returns the company responsible for the OpenGL implementation. The call to glGetString(GL_RENDERER) provides the name of the renderer, which is specific to a particular hardware platform (such as the ATI Radeon HD 5600 Series). Note that both of these do not vary from release to release, so they can be used to determine the current platform.

Of more importance to us in the context of this book is the call to glGetString(GL_SHADING_LANGUAGE_VERSION), which provides the supported GLSL version number. This string should begin with the major and minor version numbers separated by a period, but similar to the GL_VERSION query, may include other vendor-specific information.

There's more...

It is often useful to query for the supported extensions of the current OpenGL implementation. Extension names are indexed and can be individually queried by index. We use the glGetStringi variant for this. For example, to get the name of the extension stored at index i, we use glGetStringi(GL_EXTENSIONS, i). To print a list of all extensions, we could use the following code:

GLint nExtensions; 
glGetIntegerv(GL_NUM_EXTENSIONS, &nExtensions); 
 
for( int i = 0; i < nExtensions; i++ ) 
      printf("%s\n", glGetStringi( GL_EXTENSIONS, i ) );

OpenGL 4 Shading Language Cookbook - Third Edition

By : David Wolff

OpenGL 4 Shading Language Cookbook - Third Edition

By: David Wolff

Overview of this book

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