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Real-Time 3D Graphics with WebGL 2

You're reading from   Real-Time 3D Graphics with WebGL 2 Build interactive 3D applications with JavaScript and WebGL 2 (OpenGL ES 3.0)

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Product type Paperback
Published in Oct 2018
Publisher Packt
ISBN-13 9781788629690
Length 500 pages
Edition 2nd Edition
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Authors (2):
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Farhad Ghayour Farhad Ghayour
Author Profile Icon Farhad Ghayour
Farhad Ghayour
Diego Cantor Diego Cantor
Author Profile Icon Diego Cantor
Diego Cantor
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Table of Contents (14) Chapters Close

Preface 1. Getting Started FREE CHAPTER 2. Rendering 3. Lights 4. Cameras 5. Animations 6. Colors, Depth Testing, and Alpha Blending 7. Textures 8. Picking 9. Putting It All Together 10. Advanced Techniques 11. WebGL 2 Highlights 12. Journey Ahead 13. Other Books You May Enjoy

Looking for Hits

Now, we will check whether the color obtained from the offscreen framebuffer matches any of the objects in our scene. Remember here that we are using colors as object labels. If the color matches one of the objects, then we call it a hit. If it does not, we call it a miss.

When looking for hits, we compare each object's diffuse color with the label obtained from the offscreen framebuffer. There is, however, an additional step to consider: each color channel comes back in a [0, 255] range while the object diffuse colors are in a [0, 1] range. We need to update this before we check for any possible hits. We can do so with a compare function:

function compare(readout, color) {
return (
Math.abs(Math.round(color[0] * 255) - readout[0]) <= 1 &&
Math.abs(Math.round(color[1] * 255) - readout[1]) <= 1 &&
Math.abs(Math.round(color...
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