NAME¶
glEnable - enable or disable server-side GL capabilities
C SPECIFICATION¶
void
glEnable(GLenum cap);
PARAMETERS¶
cap
Specifies a symbolic constant indicating a GL
capability.
C SPECIFICATION¶
void
glDisable(GLenum cap);
PARAMETERS¶
cap
Specifies a symbolic constant indicating a GL
capability.
C SPECIFICATION¶
void
glEnablei(GLenum cap,
GLuint index);
PARAMETERS¶
cap
Specifies a symbolic constant indicating a GL
capability.
index
Specifies the index of the swtich to
enable.
C SPECIFICATION¶
void
glDisablei(GLenum cap,
GLuint index);
PARAMETERS¶
cap
Specifies a symbolic constant indicating a GL
capability.
index
Specifies the index of the swtich to
disable.
DESCRIPTION¶
glEnable and
glDisable() enable and disable various capabilities.
Use
glIsEnabled() or
glGet() to determine the current setting of
any capability. The initial value for each capability with the exception of
GL_DITHER and
GL_MULTISAMPLE is
GL_FALSE. The initial
value for
GL_DITHER and
GL_MULTISAMPLE is
GL_TRUE.
Both
glEnable and
glDisable() take a single argument,
cap,
which can assume one of the following values:
Some of the GL's capabilities are indexed.
glEnablei and
glDisablei enable and disable indexed capabilities.
GL_BLEND
If enabled, blend the computed fragment color values with the values in the
color buffers. See
glBlendFunc().
GL_CLIP_DISTANCEi
If enabled, clip geometry against user-defined half space
i.
GL_COLOR_LOGIC_OP
If enabled, apply the currently selected logical operation to the computed
fragment color and color buffer values. See
glLogicOp().
GL_CULL_FACE
If enabled, cull polygons based on their winding in window coordinates. See
glCullFace().
GL_DEPTH_CLAMP
If enabled, the
-wc≤zc≤wc plane equation is ignored by view volume clipping
(effectively, there is no near or far plane clipping). See
glDepthRange().
GL_DEPTH_TEST
If enabled, do depth comparisons and update the depth buffer. Note that even if
the depth buffer exists and the depth mask is non-zero, the depth buffer is
not updated if the depth test is disabled. See
glDepthFunc() and
glDepthRange().
GL_DITHER
If enabled, dither color components or indices before they are written to the
color buffer.
GL_FRAMEBUFFER_SRGB
If enabled and the value of
GL_FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING for
the framebuffer attachment corresponding to the destination buffer is
GL_SRGB, the R, G, and B destination color values (after conversion
from fixed-point to floating-point) are considered to be encoded for the sRGB
color space and hence are linearized prior to their use in blending.
GL_LINE_SMOOTH
If enabled, draw lines with correct filtering. Otherwise, draw aliased lines.
See
glLineWidth().
GL_MULTISAMPLE
If enabled, use multiple fragment samples in computing the final color of a
pixel. See
glSampleCoverage().
GL_POLYGON_OFFSET_FILL
If enabled, and if the polygon is rendered in
GL_FILL mode, an offset is
added to depth values of a polygon's fragments before the depth comparison is
performed. See
glPolygonOffset().
GL_POLYGON_OFFSET_LINE
If enabled, and if the polygon is rendered in
GL_LINE mode, an offset is
added to depth values of a polygon's fragments before the depth comparison is
performed. See
glPolygonOffset().
GL_POLYGON_OFFSET_POINT
If enabled, an offset is added to depth values of a polygon's fragments before
the depth comparison is performed, if the polygon is rendered in
GL_POINT mode. See
glPolygonOffset().
GL_POLYGON_SMOOTH
If enabled, draw polygons with proper filtering. Otherwise, draw aliased
polygons. For correct antialiased polygons, an alpha buffer is needed and the
polygons must be sorted front to back.
GL_PRIMITIVE_RESTART
Enables primitive restarting. If enabled, any one of the draw commands which
transfers a set of generic attribute array elements to the GL will restart the
primitive when the index of the vertex is equal to the primitive restart
index. See
glPrimitiveRestartIndex().
GL_SAMPLE_ALPHA_TO_COVERAGE
If enabled, compute a temporary coverage value where each bit is determined by
the alpha value at the corresponding sample location. The temporary coverage
value is then ANDed with the fragment coverage value.
GL_SAMPLE_ALPHA_TO_ONE
If enabled, each sample alpha value is replaced by the maximum representable
alpha value.
GL_SAMPLE_COVERAGE
If enabled, the fragment's coverage is ANDed with the temporary coverage value.
If
GL_SAMPLE_COVERAGE_INVERT is set to
GL_TRUE, invert the
coverage value. See
glSampleCoverage().
GL_SAMPLE_SHADING
If enabled, the active fragment shader is run once for each covered sample, or
at fraction of this rate as determined by the current value of
GL_MIN_SAMPLE_SHADING_VALUE. See
glMinSampleShading().
GL_SAMPLE_MASK
If enabled, the sample coverage mask generated for a fragment during
rasterization will be ANDed with the value of
GL_SAMPLE_MASK_VALUE
before shading occurs. See
glSampleMaski().
GL_SCISSOR_TEST
If enabled, discard fragments that are outside the scissor rectangle. See
glScissor().
GL_STENCIL_TEST
If enabled, do stencil testing and update the stencil buffer. See
glStencilFunc() and
glStencilOp().
GL_TEXTURE_CUBE_MAP_SEAMLESS
If enabled, cubemap textures are sampled such that when linearly sampling from
the border between two adjacent faces, texels from both faces are used to
generate the final sample value. When disabled, texels from only a single face
are used to construct the final sample value.
GL_PROGRAM_POINT_SIZE
If enabled and a vertex or geometry shader is active, then the derived point
size is taken from the (potentially clipped) shader builtin
gl_PointSize and clamped to the implementation-dependent point size
range.
ERRORS¶
GL_INVALID_ENUM is generated if
cap is not one of the values
listed previously.
GL_INVALID_VALUE is generated by
glEnablei and
glDisablei
if
index is greater than or equal to the number of indexed capabilities
for
cap.
NOTES¶
GL_PRIMITIVE_RESTART is available only if the GL version is 3.1 or
greater.
GL_TEXTURE_CUBE_MAP_SEAMLESS is available only if the GL version is 3.2
or greater.
Any token accepted by
glEnable or
glDisable is also accepted by
glEnablei and
glDisablei, but if the capability is not indexed,
the maximum value that
index may take is zero.
In general, passing an indexed capability to
glEnable or
glDisable
will enable or disable that capability for all indices, resepectively.
ASSOCIATED GETS¶
glIsEnabled()
glGet()
SEE ALSO¶
glActiveTexture(),
glBlendFunc(),
glCullFace(),
glDepthFunc(),
glDepthRange(),
glGet(),
glIsEnabled(),
glLineWidth(),
glLogicOp(),
glPointSize(),
glPolygonMode(),
glPolygonOffset(),
glSampleCoverage(),
glScissor(),
glStencilFunc(),
glStencilOp(),
glTexImage1D(),
glTexImage2D(),
glTexImage3D()
COPYRIGHT¶
Copyright © 1991-2006 Silicon Graphics, Inc. Copyright © 2010-2011
Khronos Group. This document is licensed under the SGI Free Software B
License. For details, see
http://oss.sgi.com/projects/FreeB/.
