Glstencilop opengl es book

The following example illustrates using glstencilfunc and glstencilop to control. The least significant n bits of mask, where n is the number of bits in the stencil buffer, specify a mask. Opengl es is the standard graphics api used for mobile and embedded systems. When you draw something with opengl, you see colors on the screen, but keep in mind that there are other buffers than the color buffer. But glstencilfunc only describes whether opengl should pass or discard fragments based on the stencil buffers content, not how we can actually update the.

This book is intended for programmers interested in learning opengl es. Stencil operations in opengl adjust glstencilop function that expects three values. The other two arguments to glstencilop specify stencil buffer actions that depend on whether subsequent depth buffer tests succeed dppass or fail dpfail see gldepthfunc. Despite its widespread use, there is a lack of material that addresses the balance of both theory and practice in opengl es. Opengl family, including opengl es for embedded and mobile systems, and. The following example illustrates using glstencilfunc and glstencilop to control rendering.

Opengl es is a complicated subject at the best of times but this book does an excellent job of explaining the principles and concepts of opengl es to an absolute beginner. Specifies the action to take when the stencil test fails. If you use opengl nones, you can call glreadpixels to grab the whole stencil buffer and inspect it externally, but its tedious. Where a 1 appears in the mask, its possible to write to the corresponding bit in the stencil buffer. Im working on an ios app, a coloring book for kids and i havent stumbled upon opengl before more precisely opengles 2. It is difficult to understand what is wrong when working on the stencil buffer, because we have no direct way to see it.

Stencil buffer values are treated as unsigned integers. This money will help me to travel to python conferences and to write other books as well. A stencil buffer is an extra data buffer, in addition to the color buffer and zbuffer, found on. The most recent red book parallels the grand tradition of opengl. Opengl programmingstencil buffer wikibooks, open books for an. Opengl programmingstencil buffer wikibooks, open books. This book provides outstanding coverage of the latest version of opengl es, with clear, comprehensive explanations and extensive examples.