Glstencilop opengl es book

The least significant n bits of mask, where n is the number of bits in the stencil buffer, specify a mask. The most recent red book parallels the grand tradition of opengl. Im working on an ios app, a coloring book for kids and i havent stumbled upon opengl before more precisely opengles 2. This money will help me to travel to python conferences and to write other books as well. This book is intended for programmers interested in learning opengl es. If you use opengl nones, you can call glreadpixels to grab the whole stencil buffer and inspect it externally, but its tedious. A stencil buffer is an extra data buffer, in addition to the color buffer and zbuffer, found on.

Specifies the action to take when the stencil test fails. Opengl programmingstencil buffer wikibooks, open books. But glstencilfunc only describes whether opengl should pass or discard fragments based on the stencil buffers content, not how we can actually update the. 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. 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. The following example illustrates using glstencilfunc and glstencilop to control rendering. It is difficult to understand what is wrong when working on the stencil buffer, because we have no direct way to see it. 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.