APPLE_texture_max_level

GL_APPLE_texture_max_level

Contributors to SGIS_texture_lod desktop OpenGL extension from which 
this extension borrows heavily.

Benj Lipchak, Apple (lipchak 'at' apple.com)

Complete

Last Modified Date: February 24, 2011
Revision: #2

OpenGL ES Extension #80

Written based on the wording of the OpenGL ES 2.0 specification.

OpenGL ES 1.1 affects the definition of this extension.

This extension allows an application to specify the maximum (coarsest) 
mipmap level that may be selected for the specified texture.  This maximum
level is also used to determine which mip levels are considered when 
determining texture completeness.

No known IP claims.

None

Accepted by the <pname> parameter of TexParameteri, TexParameterf,
TexParameteriv, TexParameterfv, GetTexParameteriv, and GetTexParameterfv:

    TEXTURE_MAX_LEVEL_APPLE          0x813D

None

Add the following line to Table 3.10 (Texture parameters and their values):

    Name                            Type        Legal Values
    ----                            ----        ------------
    TEXTURE_MAX_LEVEL_APPLE         integer     any non-negative integer

In section 3.7.4, insert the following paragraph before the paragraph
beginning "Texture parameters for a cube map texture...":

"In the remainder of section 3.7, denote by level_max the value of the 
texture parameter TEXTURE_MAX_LEVEL_APPLE."

In section 3.7.7 subsection "Mipmapping" modify the second paragraph
such that p and q are defined as follows:

    p = floor(log2(max(w_b, h_b)))
    q = min{p, level_max}

In section 3.7.7 subsection "Mipmapping" insert the following paragraph 
before the paragraph beginning "The mipmap is used in conjunction...":

"The value of level_max may be respecified for a specific texture by
calling TexParameter[if] with <pname> set to TEXTURE_MAX_LEVEL_APPLE.
The error INVALID_VALUE is generated if the specified value is negative."

In section 3.7.12, modify the last three sentences to read as follows:

"Next, there are the two sets of texture properties; each consists of the
selected minification and magnification filters, the maximum array level,
and the wrap modes for s and t.  In the initial state, the value assigned
to TEXTURE_MIN_FILTER is NEAREST_MIPMAP_LINEAR, and the value for 
TEXTURE_MAG_FILTER is LINEAR.  s and t wrap modes are both set to REPEAT.
The value of TEXTURE_MAX_LEVEL_APPLE is 1000."

None

None

None

On an OpenGL ES 1.1 implementation, include fixed-point flavors of
TexParameter and GetTexParameter commands.

INVALID_VALUE is generated if an attempt is made to set
TEXTURE_MAX_LEVEL_APPLE to a negative value.

Add the following to Table 6.8 (Textures (state per texture object):
                                                       Initial
Get Value                 Get Command         Type     Value     Description       Sec.
---------                 -----------------   ------   -------   -----------       ----
TEXTURE_MAX_LEVEL_APPLE   GetTexParameteriv   n x Z+   1000      Maximum texture   3.7
                                                                 array level

None

#2  02/24/2011    Benj Lipchak     Assign extension number
#1  10/29/2009    Benj Lipchak     First draft