upstream-man-pages/man3/xhtml/glEnable.xml

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   4 <?xml-stylesheet type="text/xsl" href="mathml.xsl"?><html xmlns="http://www.w3.org/1999/xhtml" xmlns:pref="http://www.w3.org/2002/Math/preference" pref:renderer="mathplayer-dl"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><link rel="stylesheet" type="text/css" href="opengl-man.css" /><title>glEnable - OpenGL 3.3 Reference Pages</title><meta name="generator" content="DocBook XSL Stylesheets V1.69.1" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glEnable"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glEnable — enable or disable server-side GL capabilities</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><p><code class="funcdef">void <b class="fsfunc">glEnable</b>(</code>GLenum <var class="pdparam">cap</var><code>)</code>;</p></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>cap</code></em></span></dt><dd><p>
   5                     Specifies a symbolic constant indicating a GL capability.
   6                 </p></dd></dl></div></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><p><code class="funcdef">void <b class="fsfunc">glDisable</b>(</code>GLenum <var class="pdparam">cap</var><code>)</code>;</p></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="parameters2"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>cap</code></em></span></dt><dd><p>
   7                     Specifies a symbolic constant indicating a GL capability.
   8                 </p></dd></dl></div></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><p><code class="funcdef">void <b class="fsfunc">glEnablei</b>(</code>GLenum <var class="pdparam">cap</var>, GLuint <var class="pdparam">index</var><code>)</code>;</p></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="parameters3"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>cap</code></em></span></dt><dd><p>
   9                     Specifies a symbolic constant indicating a GL capability.
  10                 </p></dd><dt><span class="term"><em class="parameter"><code>index</code></em></span></dt><dd><p>
  11                     Specifies the index of the swtich to enable.
  12                 </p></dd></dl></div></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><p><code class="funcdef">void <b class="fsfunc">glDisablei</b>(</code>GLenum <var class="pdparam">cap</var>, GLuint <var class="pdparam">index</var><code>)</code>;</p></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="parameters4"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>cap</code></em></span></dt><dd><p>
  13                     Specifies a symbolic constant indicating a GL capability.
  14                 </p></dd><dt><span class="term"><em class="parameter"><code>index</code></em></span></dt><dd><p>
  15                     Specifies the index of the swtich to disable.
  16                 </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
  17             <code class="function">glEnable</code> and <a href="glDisable.xml"><span class="citerefentry"><span class="refentrytitle">glDisable</span></span></a> enable and disable various capabilities.
  18             Use <a href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> or <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> to determine the current setting
  19             of any capability. The initial value for each capability with the
  20             exception of <code class="constant">GL_DITHER</code> and <code class="constant">GL_MULTISAMPLE</code> is
  21             <code class="constant">GL_FALSE</code>. The initial value for
  22             <code class="constant">GL_DITHER</code> and <code class="constant">GL_MULTISAMPLE</code> is <code class="constant">GL_TRUE</code>.
  23         </p><p>
  24             Both <code class="function">glEnable</code> and <a href="glDisable.xml"><span class="citerefentry"><span class="refentrytitle">glDisable</span></span></a> take a single argument, <em class="parameter"><code>cap</code></em>,
  25             which can assume one of the following values:
  26         </p><p>
  27             Some of the GL's capabilities are indicated. <code class="function">glEnablei</code> and <code class="function">glDisablei</code> enable and disable
  28             indexed capabilities.
  29         </p><div class="variablelist"><dl><dt><span class="term"><code class="constant">GL_BLEND</code></span></dt><dd><p>
  30                 </p><p>
  31                         If enabled,
  32                         blend the computed fragment color values with the values in the color
  33                         buffers. See <a href="glBlendFunc.xml"><span class="citerefentry"><span class="refentrytitle">glBlendFunc</span></span></a>.
  34                     </p></dd><dt><span class="term"><code class="constant">GL_CLIP_DISTANCE</code><span class="emphasis"><em>i</em></span></span></dt><dd><p>
  35                 </p><p>
  36                         If enabled, clip geometry against user-defined half space <span class="emphasis"><em>i</em></span>.
  37                     </p></dd><dt><span class="term"><code class="constant">GL_COLOR_LOGIC_OP</code></span></dt><dd><p>
  38                 </p><p>
  39                         If enabled,
  40                         apply the currently selected logical operation to the computed fragment
  41                         color and color buffer values. See <a href="glLogicOp.xml"><span class="citerefentry"><span class="refentrytitle">glLogicOp</span></span></a>.
  42                     </p></dd><dt><span class="term"><code class="constant">GL_CULL_FACE</code></span></dt><dd><p>
  43                 </p><p>
  44                         If enabled,
  45                         cull polygons based on their winding in window coordinates.
  46                         See <a href="glCullFace.xml"><span class="citerefentry"><span class="refentrytitle">glCullFace</span></span></a>.
  47                     </p></dd><dt><span class="term"><code class="constant">GL_DEPTH_CLAMP</code></span></dt><dd><p>
  48                 </p><p>
  49                         If enabled,
  50                         the
  51
  52                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  53                             <mml:mo>-</mml:mo><mml:msub><mml:mi>w</mml:mi><mml:mi>c</mml:mi></mml:msub><mml:mo>≤</mml:mo><mml:msub><mml:mi>z</mml:mi><mml:mi>c</mml:mi></mml:msub><mml:mo>≤</mml:mo><mml:msub><mml:mi>w</mml:mi><mml:mi>c</mml:mi></mml:msub>
  54                         </mml:math>
  55                         plane equation is ignored by view volume clipping (effectively, there is no near or
  56                         far plane clipping).
  57                         See <a href="glDepthRange.xml"><span class="citerefentry"><span class="refentrytitle">glDepthRange</span></span></a>.
  58                     </p></dd><dt><span class="term"><code class="constant">GL_DEPTH_TEST</code></span></dt><dd><p>
  59                 </p><p>
  60                         If enabled,
  61                         do depth comparisons and update the depth buffer. Note that even if
  62                         the depth buffer exists and the depth mask is non-zero, the
  63                         depth buffer is not updated if the depth test is disabled. See
  64                         <a href="glDepthFunc.xml"><span class="citerefentry"><span class="refentrytitle">glDepthFunc</span></span></a> and
  65                         <a href="glDepthRange.xml"><span class="citerefentry"><span class="refentrytitle">glDepthRange</span></span></a>.
  66                     </p></dd><dt><span class="term"><code class="constant">GL_DITHER</code>    </span></dt><dd><p>
  67                 </p><p>
  68                         If enabled,
  69                         dither color components or indices before they are written to the
  70                         color buffer.
  71                     </p></dd><dt><span class="term"><code class="constant">GL_FRAMEBUFFER_SRGB</code>    </span></dt><dd><p>
  72                 </p><p>
  73                         If enabled
  74                         and the value of <code class="constant">GL_FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING</code> for the
  75                         framebuffer attachment corresponding to the destination buffer is <code class="constant">GL_SRGB</code>,
  76                         the R, G, and B destination color values (after conversion from fixed-point to floating-point)
  77                         are considered to be encoded for the sRGB color space and hence are linearized prior to
  78                         their use in blending.
  79                     </p></dd><dt><span class="term"><code class="constant">GL_LINE_SMOOTH</code></span></dt><dd><p>
  80                 </p><p>
  81                         If enabled,
  82                         draw lines with correct filtering.
  83                         Otherwise,
  84                         draw aliased lines.
  85                         See <a href="glLineWidth.xml"><span class="citerefentry"><span class="refentrytitle">glLineWidth</span></span></a>.
  86                     </p></dd><dt><span class="term"><code class="constant">GL_MULTISAMPLE</code></span></dt><dd><p>
  87                 </p><p>
  88                         If enabled,
  89                         use multiple fragment samples in computing the final color of a pixel.
  90                         See <a href="glSampleCoverage.xml"><span class="citerefentry"><span class="refentrytitle">glSampleCoverage</span></span></a>.
  91                     </p></dd><dt><span class="term"><code class="constant">GL_POLYGON_OFFSET_FILL</code></span></dt><dd><p>
  92                 </p><p>
  93                         If enabled, and if the polygon is rendered in
  94                         <code class="constant">GL_FILL</code> mode, an offset is added to depth values of a polygon's
  95                         fragments before the depth comparison is performed.
  96                         See <a href="glPolygonOffset.xml"><span class="citerefentry"><span class="refentrytitle">glPolygonOffset</span></span></a>.
  97                     </p></dd><dt><span class="term"><code class="constant">GL_POLYGON_OFFSET_LINE</code></span></dt><dd><p>
  98                 </p><p>
  99                         If enabled, and if the polygon is rendered in
 100                         <code class="constant">GL_LINE</code> mode, an offset is added to depth values of a polygon's
 101                         fragments before the depth comparison is performed.
 102                         See <a href="glPolygonOffset.xml"><span class="citerefentry"><span class="refentrytitle">glPolygonOffset</span></span></a>.
 103                     </p></dd><dt><span class="term"><code class="constant">GL_POLYGON_OFFSET_POINT</code></span></dt><dd><p>
 104                 </p><p>
 105                         If enabled, an offset is added to depth values of a polygon's fragments
 106                         before the depth comparison is performed, if the polygon is rendered in
 107                         <code class="constant">GL_POINT</code> mode. See <a href="glPolygonOffset.xml"><span class="citerefentry"><span class="refentrytitle">glPolygonOffset</span></span></a>.
 108                     </p></dd><dt><span class="term"><code class="constant">GL_POLYGON_SMOOTH</code></span></dt><dd><p>
 109                 </p><p>
 110                         If enabled, draw polygons with proper filtering.
 111                         Otherwise, draw aliased polygons. For correct antialiased polygons,
 112                         an alpha buffer is needed and the polygons must be sorted front to
 113                         back.
 114                     </p></dd><dt><span class="term"><code class="constant">GL_PRIMITIVE_RESTART</code></span></dt><dd><p>
 115                 </p><p>
 116                         Enables primitive restarting.  If enabled, any one of the draw commands
 117                         which transfers a set of generic attribute array elements to the GL will restart
 118                         the primitive when the index of the vertex is equal to the primitive restart index.
 119                         See <a href="glPrimitiveRestartIndex.xml"><span class="citerefentry"><span class="refentrytitle">glPrimitiveRestartIndex</span></span></a>.
 120                     </p></dd><dt><span class="term"><code class="constant">GL_SAMPLE_ALPHA_TO_COVERAGE</code></span></dt><dd><p>
 121                 </p><p>
 122                         If enabled,
 123                         compute a temporary coverage value where each bit is determined by the
 124                         alpha value at the corresponding sample location.  The temporary coverage
 125                         value is then ANDed with the fragment coverage value.
 126                     </p></dd><dt><span class="term"><code class="constant">GL_SAMPLE_ALPHA_TO_ONE</code></span></dt><dd><p>
 127                 </p><p>
 128                         If enabled,
 129                         each sample alpha value is replaced by the maximum representable alpha value.
 130                     </p></dd><dt><span class="term"><code class="constant">GL_SAMPLE_COVERAGE</code></span></dt><dd><p>
 131                 </p><p>
 132                         If enabled,
 133                         the fragment's coverage is ANDed with the temporary coverage value.  If
 134                         <code class="constant">GL_SAMPLE_COVERAGE_INVERT</code> is set to <code class="constant">GL_TRUE</code>, invert the coverage
 135                         value.
 136                         See <a href="glSampleCoverage.xml"><span class="citerefentry"><span class="refentrytitle">glSampleCoverage</span></span></a>.
 137                     </p></dd><dt><span class="term"><code class="constant">GL_SCISSOR_TEST</code></span></dt><dd><p>
 138                 </p><p>
 139                         If enabled,
 140                         discard fragments that are outside the scissor rectangle.
 141                         See <a href="glScissor.xml"><span class="citerefentry"><span class="refentrytitle">glScissor</span></span></a>.
 142                     </p></dd><dt><span class="term"><code class="constant">GL_STENCIL_TEST</code></span></dt><dd><p>
 143                 </p><p>
 144                         If enabled,
 145                         do stencil testing and update the stencil buffer.
 146                         See <a href="glStencilFunc.xml"><span class="citerefentry"><span class="refentrytitle">glStencilFunc</span></span></a> and <a href="glStencilOp.xml"><span class="citerefentry"><span class="refentrytitle">glStencilOp</span></span></a>.
 147                     </p></dd><dt><span class="term"><code class="constant">GL_TEXTURE_CUBE_MAP_SEAMLESS</code></span></dt><dd><p>
 148                 </p><p>
 149                         If enabled, modifies the way sampling is performed on cube map textures.  See the spec for more information.
 150                     </p></dd><dt><span class="term"><code class="constant">GL_PROGRAM_POINT_SIZE</code></span></dt><dd><p>
 151                 </p><p>
 152                         If enabled
 153                         and a vertex or geometry shader is active, then the derived point size is taken from the (potentially clipped) shader builtin
 154                         <code class="constant">gl_PointSize</code> and clamped to the implementation-dependent point size range.
 155                     </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p>
 156             <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>cap</code></em> is not one of the values
 157             listed previously.
 158         </p><p>
 159             <code class="constant">GL_INVALID_VALUE</code> is generated by <code class="function">glEnablei</code> and <code class="function">glDisablei</code>
 160             if <em class="parameter"><code>index</code></em> is greater than or equal to the number of indexed capabilities for <em class="parameter"><code>cap</code></em>.
 161         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p>
 162             <code class="constant">GL_PRIMITIVE_RESTART</code> is available only if the GL version is 3.1 or greater.
 163         </p><p>
 164             <code class="constant">GL_TEXTURE_CUBE_MAP_SEAMLESS</code> is available only if the GL version is 3.2 or greater.
 165         </p><p>
 166             Any token accepted by <code class="function">glEnable</code> or <code class="function">glDisable</code> is also accepted by
 167             <code class="function">glEnablei</code> and <code class="function">glDisablei</code>, but if the capability is not indexed,
 168             the maximum value that <em class="parameter"><code>index</code></em> may take is zero.
 169         </p><p>
 170             In general, passing an indexed capability to <code class="function">glEnable</code> or <code class="function">glDisable</code>
 171             will enable or disable that capability for all indices, resepectively.
 172         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
 173             <a href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a>
 174         </p><p>
 175             <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a>
 176         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
 177             <a href="glActiveTexture.xml"><span class="citerefentry"><span class="refentrytitle">glActiveTexture</span></span></a>,
 178             <a href="glBlendFunc.xml"><span class="citerefentry"><span class="refentrytitle">glBlendFunc</span></span></a>,
 179             <a href="glCullFace.xml"><span class="citerefentry"><span class="refentrytitle">glCullFace</span></span></a>,
 180             <a href="glDepthFunc.xml"><span class="citerefentry"><span class="refentrytitle">glDepthFunc</span></span></a>,
 181             <a href="glDepthRange.xml"><span class="citerefentry"><span class="refentrytitle">glDepthRange</span></span></a>,
 182             <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a>,
 183             <a href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a>,
 184             <a href="glLineWidth.xml"><span class="citerefentry"><span class="refentrytitle">glLineWidth</span></span></a>,
 185             <a href="glLogicOp.xml"><span class="citerefentry"><span class="refentrytitle">glLogicOp</span></span></a>,
 186             <a href="glPointSize.xml"><span class="citerefentry"><span class="refentrytitle">glPointSize</span></span></a>,
 187             <a href="glPolygonMode.xml"><span class="citerefentry"><span class="refentrytitle">glPolygonMode</span></span></a>,
 188             <a href="glPolygonOffset.xml"><span class="citerefentry"><span class="refentrytitle">glPolygonOffset</span></span></a>,
 189             <a href="glSampleCoverage.xml"><span class="citerefentry"><span class="refentrytitle">glSampleCoverage</span></span></a>,
 190             <a href="glScissor.xml"><span class="citerefentry"><span class="refentrytitle">glScissor</span></span></a>,
 191             <a href="glStencilFunc.xml"><span class="citerefentry"><span class="refentrytitle">glStencilFunc</span></span></a>,
 192             <a href="glStencilOp.xml"><span class="citerefentry"><span class="refentrytitle">glStencilOp</span></span></a>,
 193             <a href="glTexImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage1D</span></span></a>,
 194             <a href="glTexImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage2D</span></span></a>,
 195             <a href="glTexImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage3D</span></span></a>
 196         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
 197             Copyright <span class="trademark"></span>© 1991-2006
 198             Silicon Graphics, Inc. Copyright <span class="trademark"></span>© 2010 Khronos Group.
 199             This document is licensed under the SGI
 200             Free Software B License. For details, see
 201             <a href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
 202         </p></div></div></body></html>