BaoXu, There is a conversion that needs to be made when calling glReadPixels (). OpenGL uses unsigned bytes, and Java uses signed bytes. To convert, cast the byte to an int. If the value is negative, then add 256.
In your particular example, a returned alpha value of -1, cast to an int, +256, results in a value of 255. This is full alpha. Cheers, Steve On Aug 2, 8:35 pm, BaoXu Jiang <baoxu.ji...@gmail.com> wrote: > Hi, > > it is always return -1 when call Android opengl es apiglReadPixels(), > it is a bug of Android? > > Thanks, --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -~----------~----~----~----~------~----~------~--~---
