How to Use Interlace and Copy Texture Together

How to Use Interlace and Copy Texture Together

One application of the interlace extension is to use it together with the copy texture extension: You can use glCopyTexSubImage2DEXT() to copy the contents of the video field to texture memory and end up with de-interlaced video.

You can interlace pixels from two images as follows:

glEnable(GL_INTERLACE_SGIX);      
< set current raster position to (xr,yr) >
glDrawPixels(width, height, GL_RGBA, GL_UNSIGNED_BYTE, I0);  
< set raster position to (xr,yr+zoomy) >
glDrawPixels(width, height, GL_RGBA, GL_UNSIGNED_BYTE, I1);

This process is equivalent to taking pixel rows (0,2,4,...) of I2 are from image I0, and rows (1,3,5,...) from image I1, as follows:

glDisable( GL_INTERLACE_SGIX);  
< set current raster position to (xr,yr)>
glDrawPixels(width, 2*height, GL_RGBA, GL_UNSIGNED_BYTE, I2);