1991-2006
Silicon Graphics, Inc.
glEnable
3G

# 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.

## 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:

`GL_ALPHA_TEST`

  If enabled, do alpha testing. See glAlphaFunc.

`GL_AUTO_NORMAL`

  If enabled, generate normal vectors when either `GL_MAP2_VERTEX_3` or `GL_MAP2_VERTEX_4` is used to generate vertices. See glMap2.

`GL_BLEND`

  If enabled, blend the computed fragment color values with the values in the color buffers. See glBlendFunc.

`GL_CLIP_PLANE` i

  If enabled, clip geometry against user-defined clipping plane i. See glClipPlane.

`GL_COLOR_LOGIC_OP`

  If enabled, apply the currently selected logical operation to the computed fragment color and color buffer values. See glLogicOp.

`GL_COLOR_MATERIAL`

  If enabled, have one or more material parameters track the current color. See glColorMaterial.

`GL_COLOR_SUM`

  If enabled and no fragment shader is active, add the secondary color value to the computed fragment color. See glSecondaryColor.

`GL_COLOR_TABLE`

  If enabled, perform a color table lookup on the incoming RGBA color values. See glColorTable.

`GL_CONVOLUTION_1D`

  If enabled, perform a 1D convolution operation on incoming RGBA color values. See glConvolutionFilter1D.

`GL_CONVOLUTION_2D`

  If enabled, perform a 2D convolution operation on incoming RGBA color values. See glConvolutionFilter2D.

`GL_CULL_FACE`

  If enabled, cull polygons based on their winding in window coordinates. See glCullFace.

`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_FOG`

  If enabled and no fragment shader is active, blend a fog color into the post-texturing color. See glFog.

`GL_HISTOGRAM`

  If enabled, histogram incoming RGBA color values. See glHistogram.

`GL_INDEX_LOGIC_OP`

  If enabled, apply the currently selected logical operation to the incoming index and color buffer indices. See glLogicOp.

`GL_LIGHT` i

  If enabled, include light i in the evaluation of the lighting equation. See glLightModel and glLight.

`GL_LIGHTING`

  If enabled and no vertex shader is active, use the current lighting parameters to compute the vertex color or index. Otherwise, simply associate the current color or index with each vertex. See glMaterial, glLightModel, and glLight.

`GL_LINE_SMOOTH`

  If enabled, draw lines with correct filtering. Otherwise, draw aliased lines. See glLineWidth.

`GL_LINE_STIPPLE`

  If enabled, use the current line stipple pattern when drawing lines. See glLineStipple.

`GL_MAP1_COLOR_4`

  If enabled, calls to glEvalCoord1, glEvalMesh1, and glEvalPoint1 generate RGBA values. See glMap1.

`GL_MAP1_INDEX`

  If enabled, calls to glEvalCoord1, glEvalMesh1, and glEvalPoint1 generate color indices. See glMap1.

`GL_MAP1_NORMAL`

  If enabled, calls to glEvalCoord1, glEvalMesh1, and glEvalPoint1 generate normals. See glMap1.

`GL_MAP1_TEXTURE_COORD_1`

  If enabled, calls to glEvalCoord1, glEvalMesh1, and glEvalPoint1 generate s texture coordinates. See glMap1.

`GL_MAP1_TEXTURE_COORD_2`

  If enabled, calls to glEvalCoord1, glEvalMesh1, and glEvalPoint1 generate s and t texture coordinates. See glMap1.

`GL_MAP1_TEXTURE_COORD_3`

  If enabled, calls to glEvalCoord1, glEvalMesh1, and glEvalPoint1 generate s, t, and r texture coordinates. See glMap1.

`GL_MAP1_TEXTURE_COORD_4`

  If enabled, calls to glEvalCoord1, glEvalMesh1, and glEvalPoint1 generate s, t, r, and q texture coordinates. See glMap1.

`GL_MAP1_VERTEX_3`

  If enabled, calls to glEvalCoord1, glEvalMesh1, and glEvalPoint1 generate x, y, and z vertex coordinates. See glMap1.

`GL_MAP1_VERTEX_4`

  If enabled, calls to glEvalCoord1, glEvalMesh1, and glEvalPoint1 generate homogeneous x, y, z, and w vertex coordinates. See glMap1.

`GL_MAP2_COLOR_4`

  If enabled, calls to glEvalCoord2, glEvalMesh2, and glEvalPoint2 generate RGBA values. See glMap2.

`GL_MAP2_INDEX`

  If enabled, calls to glEvalCoord2, glEvalMesh2, and glEvalPoint2 generate color indices. See glMap2.

`GL_MAP2_NORMAL`

  If enabled, calls to glEvalCoord2, glEvalMesh2, and glEvalPoint2 generate normals. See glMap2.

`GL_MAP2_TEXTURE_COORD_1`

  If enabled, calls to glEvalCoord2, glEvalMesh2, and glEvalPoint2 generate s texture coordinates. See glMap2.

`GL_MAP2_TEXTURE_COORD_2`

  If enabled, calls to glEvalCoord2, glEvalMesh2, and glEvalPoint2 generate s and t texture coordinates. See glMap2.

`GL_MAP2_TEXTURE_COORD_3`

  If enabled, calls to glEvalCoord2, glEvalMesh2, and glEvalPoint2 generate s, t, and r texture coordinates. See glMap2.

`GL_MAP2_TEXTURE_COORD_4`

  If enabled, calls to glEvalCoord2, glEvalMesh2, and glEvalPoint2 generate s, t, r, and q texture coordinates. See glMap2.

`GL_MAP2_VERTEX_3`

  If enabled, calls to glEvalCoord2, glEvalMesh2, and glEvalPoint2 generate x, y, and z vertex coordinates. See glMap2.

`GL_MAP2_VERTEX_4`

  If enabled, calls to glEvalCoord2, glEvalMesh2, and glEvalPoint2 generate homogeneous x, y, z, and w vertex coordinates. See glMap2.

`GL_MINMAX`

  If enabled, compute the minimum and maximum values of incoming RGBA color values. See glMinmax.

`GL_MULTISAMPLE`

  If enabled, use multiple fragment samples in computing the final color of a pixel. See glSampleCoverage.

`GL_NORMALIZE`

  If enabled and no vertex shader is active, normal vectors are normalized to unit length after transformation and before lighting. This method is generally less efficient than `GL_RESCALE_NORMAL`. See glNormal and glNormalPointer.

`GL_POINT_SMOOTH`

  If enabled, draw points with proper filtering. Otherwise, draw aliased points. See glPointSize.

`GL_POINT_SPRITE`

  If enabled, calculate texture coordinates for points based on texture environment and point parameter settings. Otherwise texture coordinates are constant across points.

`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_POLYGON_STIPPLE`

  If enabled, use the current polygon stipple pattern when rendering polygons. See glPolygonStipple.

`GL_POST_COLOR_MATRIX_COLOR_TABLE`

  If enabled, perform a color table lookup on RGBA color values after color matrix transformation. See glColorTable.

`GL_POST_CONVOLUTION_COLOR_TABLE`

  If enabled, perform a color table lookup on RGBA color values after convolution. See glColorTable.

`GL_RESCALE_NORMAL`

  If enabled and no vertex shader is active, normal vectors are scaled after transformation and before lighting by a factor computed from the modelview matrix. If the modelview matrix scales space uniformly, this has the effect of restoring the transformed normal to unit length. This method is generally more efficient than `GL_NORMALIZE`. See glNormal and glNormalPointer.

`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_SEPARABLE_2D`

  If enabled, perform a two-dimensional convolution operation using a separable convolution filter on incoming RGBA color values. See glSeparableFilter2D.

`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_1D`

  If enabled and no fragment shader is active, one-dimensional texturing is performed (unless two- or three-dimensional or cube-mapped texturing is also enabled). See glTexImage1D.

`GL_TEXTURE_2D`

  If enabled and no fragment shader is active, two-dimensional texturing is performed (unless three-dimensional or cube-mapped texturing is also enabled). See glTexImage2D.

`GL_TEXTURE_3D`

  If enabled and no fragment shader is active, three-dimensional texturing is performed (unless cube-mapped texturing is also enabled). See glTexImage3D.

`GL_TEXTURE_CUBE_MAP`

  If enabled and no fragment shader is active, cube-mapped texturing is performed. See glTexImage2D.

`GL_TEXTURE_GEN_Q`

  If enabled and no vertex shader is active, the q texture coordinate is computed using the texture generation function defined with glTexGen. Otherwise, the current q texture coordinate is used. See glTexGen.

`GL_TEXTURE_GEN_R`

  If enabled and no vertex shader is active, the r texture coordinate is computed using the texture generation function defined with glTexGen. Otherwise, the current r texture coordinate is used. See glTexGen.

`GL_TEXTURE_GEN_S`

  If enabled and no vertex shader is active, the s texture coordinate is computed using the texture generation function defined with glTexGen. Otherwise, the current s texture coordinate is used. See glTexGen.

`GL_TEXTURE_GEN_T`

  If enabled and no vertex shader is active, the t texture coordinate is computed using the texture generation function defined with glTexGen. Otherwise, the current t texture coordinate is used. See glTexGen.

`GL_VERTEX_PROGRAM_POINT_SIZE`

  If enabled and a vertex 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.

`GL_VERTEX_PROGRAM_TWO_SIDE`

  If enabled and a vertex shader is active, it specifies that the GL will choose between front and back colors based on the polygon's face direction of which the vertex being shaded is a part. It has no effect on points or lines.

## Notes

`GL_POLYGON_OFFSET_FILL`, `GL_POLYGON_OFFSET_LINE`, `GL_POLYGON_OFFSET_POINT`, `GL_COLOR_LOGIC_OP`, and `GL_INDEX_LOGIC_OP` are available only if the GL version is 1.1 or greater.

`GL_RESCALE_NORMAL`, and `GL_TEXTURE_3D` are available only if the GL version is 1.2 or greater.

`GL_MULTISAMPLE`, `GL_SAMPLE_ALPHA_TO_COVERAGE`, `GL_SAMPLE_ALPHA_TO_ONE`, `GL_SAMPLE_COVERAGE`, `GL_TEXTURE_CUBE_MAP` are available only if the GL version is 1.3 or greater.

`GL_POINT_SPRITE`, `GL_VERTEX_PROGRAM_POINT_SIZE`, and `GL_VERTEX_PROGRAM_TWO_SIDE` is available only if the GL version is 2.0 or greater.

`GL_COLOR_TABLE`, `GL_CONVOLUTION_1D`, `GL_CONVOLUTION_2D`, `GL_HISTOGRAM`, `GL_MINMAX`, `GL_POST_COLOR_MATRIX_COLOR_TABLE`, `GL_POST_CONVOLUTION_COLOR_TABLE`, and `GL_SEPARABLE_2D` are available only if `ARB_imaging` is returned from glGet with an argument of `GL_EXTENSIONS`.

For OpenGL versions 1.3 and greater, or when `ARB_multitexture` is supported, `GL_TEXTURE_1D`, `GL_TEXTURE_2D`, `GL_TEXTURE_3D`, `GL_TEXTURE_GEN_S`, `GL_TEXTURE_GEN_T`, `GL_TEXTURE_GEN_R`, and `GL_TEXTURE_GEN_Q` enable or disable the respective state for the active texture unit specified with glActiveTexture.

## Errors

`GL_INVALID_ENUM` is generated if `cap` is not one of the values listed previously.

`GL_INVALID_OPERATION` is generated if `glEnable` or glDisable is executed between the execution of glBegin and the corresponding execution of glEnd.

## Associated Gets

glIsEnabled

glGet

## See Also

glActiveTexture, glAlphaFunc, glBlendFunc, glClipPlane, glColorMaterial, glCullFace, glDepthFunc, glDepthRange, glEnableClientState, glFog, glGet, glIsEnabled, glLight, glLightModel, glLineWidth, glLineStipple, glLogicOp, glMap1, glMap2, glMaterial, glNormal, glNormalPointer, glPointSize, glPolygonMode, glPolygonOffset, glPolygonStipple, glSampleCoverage, glScissor, glStencilFunc, glStencilOp, glTexGen, glTexImage1D, glTexImage2D, glTexImage3D

## 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/.