I hope someone can clarify some of these concepts. Does OpenGL define texture coordinate (0,0) at the center or the edge of the pixel?
In other words suppose I have a texture that’s 4x4 pixels in size. Using texture coordinates if I wanted to access original pixel (0,0) (memory coordinate) would texture coordinates be (0,0) or (1/4/2, 1/4/2)? Likewise would the pixel (3,3) be (1,1) or (0.75 + 1/4/2, 0.75 + 1/4/2) in texture coords?
I’ve been looking at figure 3.6 page 190 of the spec. It seems like the center of the pixel is used as origin for coordinates, and texture coordinates (0,0), (0.25, 0.25), (0.5, 0.5) … will give me original un-interpolated pixel values.