>Psychtoolbox>PsychTests

passedFlag=AlphaMultipicationTest([screenNumber])

AlphaMultiplicationTest:

Test for perfect alpha multiplication precision for alpha values 0 and  
1. [OpenGL](OpenGL) guarantees precise alpha muliplicaion for only those alpha  
values. [TestTestAlphaMultipicationAlphaTimes](TestTestAlphaMultipicationAlphaTimes) tests that guarantee.   
  
Test all alpha modes in all combinations.  This verifies that [Screen](Screen) sets  
modes properly  

Note that Screen alpha values fall in the range 0-255 while OpenGL alpha
values are normalized between 0-1; OpenGL alpha value 1 is equivalent to
Screen alpha value 255.

If no return argument is provided, then AlphaMultiplicationTest issues an error
when a test fails. If a return argument is supplied then it signals a
failed test only by returning true, without issuing an error.

See also: AlphaBlendingTest, PsychAlphaBlending