How to easily flip OpenGL images right-side up?

Question

How to easily flip OpenGL images right-side up?

Does anyone have a simple solution for loading images into OpenGL textures so they are right-side up.

I know I could simply save my images upside-down but hoped there was an easier solution around the fact that OpenGL's image texture coordinate starts in the lower-left.

Thanks,
Anthony

iPhone

Posted on Jan 21, 2009 8:12 AM

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Answer 1

Jan 21, 2009 10:12 AM in response to Community User

This is what I'm doing. brushData is the initial image file data. And brushData2 is the data turned upside down to send to opengl... :


 GLubyte *brushData2 = (GLubyte *) malloc(width*height *4);
 
 
 for(int i=0;i<height;i++)
 for(int j=0;j<width*4;j++) {
 
 brushData2[(height-1-i)width4 + j]=brushData[iwidth4+j];
 
 }
 free(brushData);

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Answer 2

Jan 21, 2009 11:07 AM in response to iphonemediaman

Thanks! That was what I'd planned to do but hoped to not need to duplicate my memory allocation. Given how small my texture files are though, that should be a problem.

You saved me from having to figure out the pixel re-positionings though so much thanks.

Anthony

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Answer 3

Jan 21, 2009 11:22 AM in response to Community User

You're welcome.

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