GLGETTEXENV(3G)

NAME
glGetTexEnv - return texture environment parameters

C SPECIFICATION

void glGetTexEnvfv(GLenum target, GLenum pname, GLfloat * params);

void glGetTexEnviv(GLenum target, GLenum pname, GLint * params);

PARAMETERS

target
    Specifies a texture environment. May be GL_TEXTURE_ENV, GL_TEXTURE_FILTER_CONTROL, or GL_POINT_SPRITE.

pname
    Specifies the symbolic name of a texture environment parameter. Accepted values are GL_TEXTURE_ENV_MODE, GL_TEXTURE_ENV_COLOR, GL_TEXTURE_LOD_BIAS, GL_COMBINE_RGB, GL_COMBINE_ALPHA, GL_SRC0_RGB, GL_SRC1_RGB, GL_SRC2_RGB, GL_SRC0_ALPHA, GL_SRC1_ALPHA, GL_SRC2_ALPHA, GL_OPERAND0_RGB, GL_OPERAND1_RGB, GL_OPERAND2_RGB, GL_OPERAND0_ALPHA, GL_OPERAND1_ALPHA, GL_OPERAND2_ALPHA, GL_RGB_SCALE, GL_ALPHA_SCALE, or GL_COORD_REPLACE.

params
    Returns the requested data.

DESCRIPTION

glGetTexEnv returns in params selected values of a texture environment that was specified with glTexEnv(). target specifies a texture environment.

When target is GL_TEXTURE_FILTER_CONTROL, pname must be GL_TEXTURE_LOD_BIAS. When target is GL_POINT_SPRITE, pname must be GL_COORD_REPLACE. When target is GL_TEXTURE_ENV, pname can be GL_TEXTURE_ENV_MODE, GL_TEXTURE_ENV_COLOR, GL_COMBINE_RGB, GL_COMBINE_ALPHA, GL_RGB_SCALE, GL_ALPHA_SCALE, GL_SRC0_RGB, GL_SRC1_RGB, GL_SRC2_RGB, GL_SRC0_ALPHA, GL_SRC1_ALPHA, or GL_SRC2_ALPHA.

pname names a specific texture environment parameter, as follows:

GL_TEXTURE_ENV_MODE
    params returns the single-valued texture environment mode, a symbolic constant. The initial value is GL_MODULATE.

GL_TEXTURE_ENV_COLOR
    params returns four integer or floating-point values that are the texture environment color. Integer values, when requested, are linearly mapped from the internal floating-point representation such that 1.0 maps to the most positive representable integer, and -1.0 maps to the most negative representable integer. The initial value is (0, 0, 0, 0).

GL_TEXTURE_LOD_BIAS
    params returns a single floating-point value that is the texture level-of-detail bias. The initial value is 0.

GL_COMBINE_RGB
    params returns a single symbolic constant value representing the current RGB combine mode. The initial value is GL_MODULATE.

GL_COMBINE_ALPHA
    params returns a single symbolic constant value representing the current alpha combine mode. The initial value is GL_MODULATE.

GL_SRC0_RGB
    params returns a single symbolic constant value representing the texture combiner zero's RGB source. The initial value is GL_TEXTURE.

GL_SRC1_RGB
    params returns a single symbolic constant value representing the texture combiner one's RGB source. The initial value is GL_PREVIOUS.

GL_SRC2_RGB
    params returns a single symbolic constant value representing the texture combiner two's RGB source. The initial value is GL_CONSTANT.

GL_SRC0_ALPHA
    params returns a single symbolic constant value representing the texture combiner zero's alpha source. The initial value is GL_TEXTURE.

GL_SRC1_ALPHA
    params returns a single symbolic constant value representing the texture combiner one's alpha source. The initial value is GL_PREVIOUS.

GL_SRC2_ALPHA
    params returns a single symbolic constant value representing the texture combiner two's alpha source. The initial value is GL_CONSTANT.

GL_OPERAND0_RGB
    params returns a single symbolic constant value representing the texture combiner zero's RGB operand. The initial value is GL_SRC_COLOR.

GL_OPERAND1_RGB
    params returns a single symbolic constant value representing the texture combiner one's RGB operand. The initial value is GL_SRC_COLOR.

GL_OPERAND2_RGB
    params returns a single symbolic constant value representing the texture combiner two's RGB operand. The initial value is GL_SRC_ALPHA.

GL_OPERAND0_ALPHA
    params returns a single symbolic constant value representing the texture combiner zero's alpha operand. The initial value is GL_SRC_ALPHA.

GL_OPERAND1_ALPHA
    params returns a single symbolic constant value representing the texture combiner one's alpha operand. The initial value is GL_SRC_ALPHA.

GL_OPERAND2_ALPHA
    params returns a single symbolic constant value representing the texture combiner two's alpha operand. The initial value is GL_SRC_ALPHA.

GL_RGB_SCALE
    params returns a single floating-point value representing the current RGB texture combiner scaling factor. The initial value is 1.0.

GL_ALPHA_SCALE
    params returns a single floating-point value representing the current alpha texture combiner scaling factor. The initial value is 1.0.

GL_COORD_REPLACE
    params returns a single boolean value representing the current point sprite texture coordinate replacement enable state. The initial value is GL_FALSE.

NOTES

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

For OpenGL versions 1.3 and greater, or when the ARB_multitexture extension is supported, glGetTexEnv returns the texture environment parameters for the active texture unit.

GL_COMBINE_RGB, GL_COMBINE_ALPHA, GL_SRC0_RGB, GL_SRC1_RGB, GL_SRC2_RGB, GL_SRC0_ALPHA, GL_SRC1_ALPHA, GL_SRC2_ALPHA, GL_OPERAND0_RGB, GL_OPERAND1_RGB, GL_OPERAND2_RGB, GL_OPERAND0_ALPHA, GL_OPERAND1_ALPHA, GL_OPERAND2_ALPHA, GL_RGB_SCALE, and GL_ALPHA_SCALE are available only if the GL version is 1.3 or greater.

GL_TEXTURE_FILTER_CONTROL and GL_TEXTURE_LOD_BIAS are available only if the GL version is 1.4 or greater.

GL_POINT_SPRITE and GL_COORD_REPLACE are available only if the GL version is 2.0 or greater.

ERRORS

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

GL_INVALID_OPERATION is generated if glGetTexEnv is executed between the execution of glBegin() and the corresponding execution of glEnd().

SEE ALSO

glActiveTexture(), glTexEnv()

COPYRIGHT

Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.