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()