glReadPixels Question

1,813

Author

August 02, 2007 02:31 PM

Hi, I'm trying to use glReadPixels() to get the color of a single pixel at coordinates (x,y). I checked the documentation, but I couldn't find anything. So, can someone give me a few lines of code that returns data=(red, green, blue)? Thanks, Geometrian

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dpadam450

2,403

August 02, 2007 02:47 PM

What does your current function look like?

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Geometrian

1,813

Author

August 02, 2007 02:51 PM

I don't have one. I don't know how to make one, so that's my question.

[size="1"]And a Unix user said rm -rf *.* and all was null and void...|There's no place like 127.0.0.1|The Application "Programmer" has unexpectedly quit. An error of type A.M. has occurred.
[size="2"]

Geometrian

1,813

Author

August 02, 2007 03:52 PM

glReadPixelsb(x, y, 1, 1, GL_RGB) works. Thanks for looking, everyone.

[size="1"]And a Unix user said rm -rf *.* and all was null and void...|There's no place like 127.0.0.1|The Application "Programmer" has unexpectedly quit. An error of type A.M. has occurred.
[size="2"]

zedz

291

August 02, 2007 04:56 PM

b == byte the -128->127 i think u perhaps want to use ub == unsigned byte which is 0->255

Geometrian

1,813

Author

August 02, 2007 05:05 PM

Where would I put that?
G

[size="1"]And a Unix user said rm -rf *.* and all was null and void...|There's no place like 127.0.0.1|The Application "Programmer" has unexpectedly quit. An error of type A.M. has occurred.
[size="2"]

Redien

122

August 02, 2007 06:38 PM

Instead of glReadPixelsb(x, y, 1, 1, GL_RGB) use glReadPixelsub(x, y, 1, 1, GL_RGB). :)

Geometrian

1,813

Author

August 02, 2007 06:42 PM

I see, but why would it make a difference?
G

[size="1"]And a Unix user said rm -rf *.* and all was null and void...|There's no place like 127.0.0.1|The Application "Programmer" has unexpectedly quit. An error of type A.M. has occurred.
[size="2"]

Redien

122

August 02, 2007 06:48 PM

When you use the glReadPixelsb(x, y, 1, 1, GL_RGB) function it returns an array of signed bytes. I.E. the byte has a both positive and negative side ranging from -128 to 127 as mentioned before. But since standard RGB values range from 0 to 255 you would want to use the function that returns unsigned bytes which also range from 0 to 255.

Geometrian

1,813

Author

August 02, 2007 06:52 PM

That's weird, the function works exactly as it should, perhaps because I'm using Python?

[size="1"]And a Unix user said rm -rf *.* and all was null and void...|There's no place like 127.0.0.1|The Application "Programmer" has unexpectedly quit. An error of type A.M. has occurred.
[size="2"]

glReadPixels Question

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