glGetTexLevelParameter Subroutine

OpenGL 1.1 for AIX: Reference Manual

glGetTexLevelParameter Subroutine

Purpose

Returns texture parameter values for a specific level of detail.

Library

OpenGL C bindings library: libGL.a

C Syntax

void glGetTexLevelParameterfv(GLenum target,
            GLint level, 
            GLenum pname, 
            GLfloat *params)

void glGetTexLevelParameteriv(GLenum target,
            GLint level, 
            GLenum pname, 
            GLint *params)

Parameters

target	Specifies the symbolic name of the target texture, either GL_TEXTURE_1D, GL_TEXTURE_2D, GL_PROXY_TEXTURE_1D, or GL_PROXY_TEXTURE_2D, GL_PROXY_TEXTURE_3D_EXT, GL_TEXTURE_3D_EXT.
level	Specifies the level-of-detail number of the desired image. Level 0 is the base image level. Level n is the nth mipmap reduction image.
pname	Specifies the symbolic name of a texture parameter. GL_TEXTURE_DEPTH_EXT, GL_TEXTURE_WIDTH, GL_TEXTURE_HEIGHT, GL_TEXTURE_INTERNAL_FORMAT, GL_TEXTURE_BORDER, GL_TEXTURE_RED_SIZE, GL_TEXTURE_GREEN_SIZE, GL_TEXTURE_BLUE_SIZE, GL_TEXTURE_ALPHA_SIZE, GL_TEXTURE_LUMINANCE_SIZE, and GL_TEXTURE_INTENSITY_SIZE are accepted.
params	Returns the requested data.

Description

The glGetTexLevelParameter subroutine returns in params texture parameter values for a specific level-of-detail value, specified as level. The target parameter defines the target texture, either GL_TEXTURE_1D, GL_TEXTURE_2D, GL_TEXTURE_3D_EXT, GL_PROXY_TEXTURE_1D, GL_PROXY_TEXTURE_2D, or GL_PROXY_TEXTURE_3D_EXT.

The GL_MAX_TEXTURE_SIZE parameter reports the largest square texture image which can be accomodated with mipmaps and borders (but a long skinny texture, or a texture without mipmaps and borders, may easily fit in texture memory). The proxy targets allow the user to more accurately query whether the GL can accomodate a texture of a given configuration. If the texture cannot be accomodated, the texture state variables (which may be queried with glGetTexLevelParameter) are set to 0. If the texture can be accomodated the texture state values will be set as they would be set for a non-proxy target.

The pname parameter specifies the texture parameter whose value or values will be returned.

The accepted parameter names are as follows:

GL_TEXTURE_ALPHA_SIZE	The internal storage resolution of an individual alpha component. The resolution chosen by the GL will be a close match for the resolution requested by the user with the component argument of glTexImage1D, glTexImage2D, or glTexImage3DEXT. The initial value is 0.
GL_TEXTURE_BLUE_SIZE	The internal storage resolution of an individual blue component. The resolution chosen by the GL will be a close match for the resolution requested by the user with the component argument of glTexImage1D, glTexImage2D, or glTexImage3DEXT. The initial value is 0.
GL_TEXTURE_BORDER	params returns a single value, the width in pixels of the border of the texture image. The inital value is 0.
GL_TEXTURE_DEPTH	params returns a single value, the depth of the texture image. This value includes the border of the texture image. The initial value is 0.
GL_TEXTURE_DEPTH_EXT	params returns a single value, the depth of the texture image. This value includes the border of the texture image. The initial value is 0.
GL_TEXTURE_GREEN_SIZE	The internal storage resolution of an individual green component. The resolution chosen by the GL will be a close match for the resolution requested by the user with the component argument of glTexImage1D, glTexImage2D, or glTexImage3DEXT. The initial value is 0.
GL_TEXTURE_HEIGHT	params returns a single value, the height of the texture image. This value includes the border of the texture image. The initial value is 0.
GL_TEXTURE_INTENSITY_SIZE	The internal storage resolution of an individual component. The resolution chosen by the GL will be a close match for the resolution requested by the user with the component argument of glTexImage1D or glTexImage2D. The initial value is 0.
GL_TEXTURE_INTERNAL_FORMAT	params returns a single value, the requested internal format of the texture image.
GL_TEXTURE_LUMINANCE_SIZE	The internal storage resolution of an individual luminance component. The resolution chosen by the GL will be a close match for the resolution requested by the user with the component argument of glTexImage1D, glTexImage2D, or glTexImage3DEXT. The initial value is 0.
GL_TEXTURE_RED_SIZE	The internal storage resolution of an individual red component. The resolution chosen by the GL will be a close match for the resolution requested by the user with the component argument of glTexImage1D, glTexImage2D, or glTexImage3DEXT. The initial value is 0.
GL_TEXTURE_WIDTH	params returns a single value, the width of the texture image. This value includes the border of the texture image. The initial value is 0.

Notes

If an error is generated, no change is made to the contents of params.

The GL_TEXTURE_INTERNAL_FORMAT parameter is only available if the GL version is 1.1 or greater. In version 1.0, use GL_TEXTURE_COMPONENTS instead.

Errors

GL_INVALID_ENUM is generated if target or pname is not an accepted value.

GL_INVALID_VALUE is generated if level is less than zero.

GL_INVALID_VALUE may be generated if level is greater than log sub 2 max, where max is the returned value of GL_MAX_TEXTURE_SIZE.

GL_INVALID_OPERATION is generated if glGetTexLevelParameter is executed between the execution of glBegin and the corresponding execution of glEnd.

Files

/usr/include/GL/gl.h

Contains C language constants, variable type definitions, and ANSI function prototypes for OpenGL.

Related Information

The glGetTexParameter subroutine, glTexImage1D subroutine, glTexImage2D subroutine, glTexParameter subroutine.

OpenGL Overview.