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Android Game Programming By Example

You're reading from   Android Game Programming By Example Harness the power of the Android SDK by building three immersive and captivating games

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Product type Paperback
Published in Jun 2015
Publisher
ISBN-13 9781785280122
Length 388 pages
Edition 1st Edition
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Author (1):
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John Horton John Horton
Author Profile Icon John Horton
John Horton
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Table of Contents (13) Chapters Close

Preface 1. Player 1 UP FREE CHAPTER 2. Tappy Defender – First Step 3. Tappy Defender – Taking Flight 4. Tappy Defender – Going Home 5. Platformer – Upgrading the Game Engine 6. Platformer – Bob, Beeps, and Bumps 7. Platformer – Guns, Life, Money, and the Enemy 8. Platformer – Putting It All Together 9. Asteroids at 60 FPS with OpenGL ES 2 10. Move and Draw with OpenGL ES 2 11. Things That Go Bump – Part II Index

Precise collision detection with the border


To upgrade our detect method, we need to replace the return statement in the if(possibleCollision) block with the more precise detection code.

First, initialize radianAngle to be the radian equivalent of whichever direction (in degrees) our object is facing. The Math class uses radians as they are more mathematically useful in calculations than the easier to visualize degree measurement.

The variables cosAngle and sinAngle are just what the name suggests, and are used in the block of code which follows this one.

Tip

It is worth mentioning that the Math.cos() and Math.sin() methods are relatively time consuming. We can speed up our collision detection class by precomputing 360 values for both sin and cos and then using a simple lookup method instead of this calculation.

However, we maintain our goal of over 60 frames per second, so don't do so here.

Delete the return statement and add this code in the if(possibleCollision) block:

if (possibleCollision...
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