Meaning of: GLfixed frame_speed = (1 16)
Author
Dear Everybody,
I try to understand OpenGL ES, but this line does not make sense to me, even after reading C++ help.
GLfixed frame_speed = (1 << 16);
Can anybody help to explain, please. GLfixed should be 32 bit fixed point interger having format (s15.16).
Regards,
Rene
[Edited by - bunkai on September 12, 2009 1:39:41 PM]
I assume thats just a 'easier' way of writing that number, I often do similar things eg
x += (8*16 + 8);
I could of writen 136 but writing (8*16 + 8) perhaps makes it clearer why the number comes to 136
x += (8*16 + 8);
I could of writen 136 but writing (8*16 + 8) perhaps makes it clearer why the number comes to 136
Its because of the GLfixed format. That line appears to be saying that it wants the "frame_speed" to be equal to 1. If you just had the line
GLfixed frame_speed = 1;
Then it wouldn't actually be equal to 1 instead it would be equal to (1>>16).
Therefore to get the correct fixed-point value you must shift it along to the correct place within the 32bit field, which is why you have:
GLfixed frame_speed = (1 << 16);
http://en.wikipedia.org/wiki/Fixed-point_arithmetic
Andy
GLfixed frame_speed = 1;
Then it wouldn't actually be equal to 1 instead it would be equal to (1>>16).
Therefore to get the correct fixed-point value you must shift it along to the correct place within the 32bit field, which is why you have:
GLfixed frame_speed = (1 << 16);
http://en.wikipedia.org/wiki/Fixed-point_arithmetic
Andy
Author
Dear Zedz, Andy,
Thank you both for explanation. Now it is clear to me.
With best regards,
Rene
Thank you both for explanation. Now it is clear to me.
With best regards,
Rene
This topic is closed to new replies.
Advertisement
Popular Topics
Advertisement
