OpenGL glBlendFunc Inverted Colors

[Spoonsx21]

Hello,

Honestly, I rarely post on forums, as I can usually google search my way to a solution, but I just don't know how to answer this question, or what I'm doing wrong.

When I attempt to draw my images on the screen, the actual images have inverted colors, i.e. 255 = 0, and 0 = 255.

This is my call to:
glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)
and GL_BLEND enabled and all. The images are just negatives of what they should be. Take a look at the pictures,

Here is what it looks like on the iphone simulator (and device):
http://www.flickr.com/photos/26806198@N03/4354347223/
Here's what the images look like:
http://www.flickr.com/photos/26806198@N03/4354347251/
http://www.flickr.com/photos/26806198@N03/4354347275/

What could be causing this? Please help, I've scoured the internet, with no luck. This is my last hope.

-Paul

[Spoonsx21]

Good news, I found out the answer, and since, maybe, just maybe some day in the future, somebody has the same issue and googles this, they'll find an answer.

When you're initializing OpenGL, in the call to glTexEnvi(...)
You want glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_BLEND_SRC)

If you have GL_BLEND instead of GL_BLEND_SRC, you will get inverted colors.
So make GL_BLEND -> GL_BLEND_SRC for the fix.

Hope this helps someone in the future. Thanks anyone who read this, wanted to help, but couldn't.

-Paul

[mlfarrell]

That is still wrong. You should really read the man pages for these routines. You are passing invalid enums to the routine. It should be for default behavior: You want glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE)

[Spoonsx21]

Thank you!

That works just the same, in terms of a fix, but I suppose it's better than what I have since it's not sending openGL invalid enums.

As far as reading the manual, this wouldn't have helped originally, as I was unaware that glTexEnvi was causing my problems. I would have had to read about pretty much every function I was calling, which I'm not sure would be helpful as much as it is time consuming.

[angelFrog]

By any chance are the pix from the simulator running on a PPC Mac? They look an awful lot like what I was seeing when I first started with iPhone programming and tricked the installer into letting me use my old G5. It mostly worked but images on the simulator came out very strangely. Not exactly inverted, but very close. The images should look okay on the device itself though.

If you are running on a PPC then the only way to get the Simulator to draw properly is to get an Intel Mac. Apple doesn't support iPhone development on PPC

If you're not running on a PPC, then I unfortunately have no other ideas...