trigonometry


Flipping an angle using radians


Hello all you math whizzes out there!
I am struggling with a math problem I am hoping you can help me with. I have calculated an angle of direction using radians. Within OpenGL ES I move my guy by changing my point value as such:
spriteLocation.x -= playerSpeed * cosf(playerRadAngle);
spriteLocation.y -= playerSpeed * sinf(playerRadAngle);
// playerRadAgnle is my angle of direction using radians
This works very well to move my sprite in the correct direction. However, I have decided to keep my sprite "locked" in the middle of the screen and move the background instead. This requires me to Reverse my calculated angle. If my sprite's direction in radians is equivalent to 90 degrees, I want to convert it to 270 degrees. Again, keeping everything in radians.
I will admit that my knowledge of Trig is poor at best. Is there a way to figure out the opposite angle using radians? I know I could convert my radians into degrees, then add/subtract 180 degrees, then convert back to radians, but I'm looking for something more efficient.
Thanks in advance....
-Scott
Add/subtract pi instead.

Related Links

Trigonometry & Sunset
Calculating collisions with Radians incrementing
How do arbitrary-precision libraries like mpmath evaluate simple trigonometric functions?
How can I calculate the angle
Finding Shortest Distance Between Two Parallel Lines, With Arbitrary Point [closed]
how to convert depth in Z-cordinate
How can I simplify this expression with trigonometric in Maple?
Require trigonometry assistance with ship/wave movement
Trigonometry - Find where two curves intersect
How to calculate point 'along' unit circle radian [closed]
Issues with bullet entry points for “shoulder mounted” guns
Using the coordinates of two of a triangle's vertices to calculate the coordinates of the third
How to do the trig function Arc Cos (ACOS() in Excel) in MS-Access?
How to get the direction (angle) of rectangle after rotating it from a pivot point
How to calculate points of Chord
Is trigonometry computationally expensive?

Categories

HOME
fabricjs
kentico
jpa
paraview
cheerio
developer-tools
alarm
access
rom
gembox-spreadsheet
mapbox
google-admin-sdk
little-proxy
octave
vimdiff
appcelerator-studio
naivebayes
libc
code-generation
frequency-distribution
symmetricds
mongodb-csharp
google-content-api
nim
breadth-first-search
blade
strongname
custom-post-type
has-and-belongs-to-many
entity-relationship-model
linked-data
8051
winpe
baidu-map
getlasterror
ideascript
postgresql-8.4
dbnull
sharp-snmp
install.packages
claims
ssrs-2014
x++
dynamic-linq
opennms
amq
compiler-design
cup
seq
gpg-signature
gameplay-kit
visual-studio-2008-sp1
stripe-connect
autosar
reporting-services-2012
scaffolding
android-dateutils
swizzling
mediametadataretriever
sklearn-pandas
beanstalk
blitline
atan2
boomerang
r-package
dllimport
linked-tables
j-security-check
gamekit
infosphere-spl
webmatrix-3
angular-gettext
jbake
administration
with-statement
mintty
vsx
renderer
vbe
square-bracket
kendo-dataviz
ie8-compatibility-mode
mbunit
cnf
actiondispatch
android-sdk-2.3
device-width
patricia-trie
database-create
ikimagebrowserview
winmain
xcelsius
umra
twitterizer
vs-android
glui

Resources

Mobile Apps Dev
Database Users
javascript
java
csharp
php
android
MS Developer
developer works
python
ios
c
html
jquery
RDBMS discuss
Cloud Virtualization
Database Dev&Adm
javascript
java
csharp
php
python
android
jquery
ruby
ios
html
Mobile App
Mobile App
Mobile App