glGetTexEnv — return texture environment parameters
void glGetTexEnvfv( | GLenum | target, |
| GLenum | pname, | |
| GLfloat * | params); |
void glGetTexEnviv( | GLenum | target, |
| GLenum | pname, | |
| GLint * | params); |
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.
paramsReturns the requested data.
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
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.
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.
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.
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/.