Book Image

OpenGL Development Cookbook

By : Muhammad Mobeen Movania
Book Image

OpenGL Development Cookbook

By: Muhammad Mobeen Movania

Overview of this book

OpenGL is the leading cross-language, multi-platform API used by masses of modern games and applications in a vast array of different sectors. Developing graphics with OpenGL lets you harness the increasing power of GPUs and really take your visuals to the next level. OpenGL Development Cookbook is your guide to graphical programming techniques to implement 3D mesh formats and skeletal animation to learn and understand OpenGL. OpenGL Development Cookbook introduces you to the modern OpenGL. Beginning with vertex-based deformations, common mesh formats, and skeletal animation with GPU skinning, and going on to demonstrate different shader stages in the graphics pipeline. OpenGL Development Cookbook focuses on providing you with practical examples on complex topics, such as variance shadow mapping, GPU-based paths, and ray tracing. By the end you will be familiar with the latest advanced GPU-based volume rendering techniques.
Table of Contents (15 chapters)
OpenGL Development Cookbook
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Implementing per-fragment spot light


We will now implement per-fragment spot light. Spot light is a special point light that emits light in a directional cone. The size of this cone is determined by the spot cutoff amount, which is given in angles, as shown in the following figure. In addition, the sharpness of the spot is controlled by the parameter spot exponent. A higher value of the exponent gives a sharper falloff and vice versa.

Getting started

The code for this recipe is contained in the Chapter4/SpotLight directory. The vertex shader is the same as in the point light recipe. The fragment shader calculates the diffuse component, as in the Implementing per-vertex and per-fragment point lighting recipe.

How to do it…

Let us start this recipe by following these simple steps:

  1. From the light's object space position and spot light target's position, calculate the spot light direction vector in eye space.

    spotDirectionES  = glm::normalize(glm::vec3(MV*glm::vec4(spotPositionOS-lightPosOS,0)))
  2. In...