The specification is not clear to me. Difference between NPOT and GL_TEXTURERECTANGLE_ARB, can you help at this :-
From the official specification
NPOTS textures are accessed by dimension-dependent (aka
non-normalized) texture coordinates. So instead of thinking of
the texture image lying in a [0…1]x[0…1] range, the NPOTS texture
image lies in a [0…w]x[0…h] range.
Then it says:
- Should 1D, 2D, 3D, or cube map textures be allowed to be NPOTS by
No. The ARB_texture_non_power_of_two extension relaxes the
power-of-two restrictions for these conventional texture targets to
support NPOTS while maintaining the normalized texture coordinates.
In the second extract it says that NPOT maintains normalized coordinates while in first it implies non-normalized.
- How is the image of a rectangular texture specified?
Using the standard OpenGL API for specifying a 2D texture
image: glTexImage2D, glSubTexImage2D, glCopyTexImage2D,
and glCopySubTexImage2D. The target for these commands is
This is similar to how the texture cube map functionality uses the 2D
texture image specification API though with its own texture target.
The texture target GL_TEXTURE_RECTANGLE_ARB should also
be used for glGetTexImage, glGetTexLevelParameteriv, and
If GL_TEXTURE_RECTANGLE_ARB is used then is NPOT = GL_TEXTURE_RECTANGLE_ARB???
Frankly, I am not able to distinguish between the two.