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
.
params
Returns 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/.