EXT/NV_texture_rectangle in 1.5spec

OpenGL OpenGL: Advanced Coding
1

according to the 1.5spec ARB_texture_non_power_of_two is specified by the ARB. i am a little bit confused, does this include the EXT/NV_texture_rectangle? in my opinion not!

p.s. does there exist a EXT_texture_rectangle? because the latest glext.h does not include it. i know it is the same as NV_tr, but is it only available in the ATi headers?

2

There is absolutely no difference between the EXT and NV texture rectangle.

from glext.h:

#ifndef GL_NV_texture_rectangle
#define GL_TEXTURE_RECTANGLE_NV 0x84F5
#define GL_TEXTURE_BINDING_RECTANGLE_NV 0x84F6
#define GL_PROXY_TEXTURE_RECTANGLE_NV 0x84F7
#define GL_MAX_RECTANGLE_TEXTURE_SIZE_NV 0x84F8
#endif

from glati.h

#ifndef GL_EXT_texture_rectangle
#define GL_EXT_texture_rectangle 1
#define GL_TEXTURE_RECTANGLE_EXT 0x84F5
#define GL_TEXTURE_BINDING_RECTANGLE_EXT 0x84F6
#define GL_PROXY_TEXTURE_RECTANGLE_EXT 0x84F7
#define GL_MAX_RECTANGLE_TEXTURE_SIZE_EXT 0x84F8
#endif /* GL_EXT_texture_rectangle */

Nico

3

Also, from the extension spec:

  1. How is a conventional NPOT target different from the texture rectangle
    target?

    STATUS: RESOLVED

    RESOLUTION:
    The biggest practical difference is that coventional targets use
    normalized texture coordinates (ie, [0…1]) while the texture
    rectangle target uses unnormalized (ie, [0…w]x[0…h]) texture
    coordinates.

    Differences include:

    • In ARB_texture_non_power_of_two:
      • mipmapping is allowed, default filter remains unchanged.
      • all wrap modes are allowed, default wrap mode remains unchanged.
      • borders are supported.
      • paletted textures are not unsupported.
      • texture coordinates are addressed parametrically [0…1],[0…1]
    • In EXT_texture_rectangle:
      • mipmapping is not allowed, default filter is changed to LINEAR.
      • only CLAMP* wrap modes are allowed, default is CLAMP_TO_EDGE.
      • borders are not supported.
      • paletted textures are unsupported.
      • texture coordinates are addressed non-parametrically [0…w],[0…h].

Nico

4

Originally posted by -NiCo-:
There is absolutely no difference between the EXT and NV texture rectangle.
i know, but i ask myself, why isn’t the EXT stuff in the latest glext.h and only in the (proprietary) ati header file.

5

The EXT extension is an apple specification which hasn’t been added to the extension registry. As you can see on http://oss.sgi.com/projects/ogl-sample/registry/

Contributors to the specification include Mark Kilgard from nvidia and Geoff Stahl from apple. Maybe it’s an intellectual property issue.

Greetz,

Nico