[clinton/guile-figl.git] / upstream-doc / manglsl / xhtml / gl_Position.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "xhtml1-transitional.dtd">
<!-- saved from url=(0013)about:internet -->
<?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>gl_Position - OpenGL Shading Language (GLSL)</title><meta name="generator" content="DocBook XSL Stylesheets V1.69.1" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="gl_Position"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>gl_Position — contains the position of the current vertex</p></div><div class="refsynopsisdiv"><h2>Declaration</h2><p>
            <code class="function">gl_Position</code> is a member of the <code class="function">gl_PerVertex</code>
            named block:
        </p><div class="funcsynopsis"><pre class="programlisting">    out gl_PerVertex {
        vec4 gl_Position;
        float gl_PointSize;
        float gl_ClipDistance[];
    };</pre></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
            In the vertex, tessellation evaluation and geoemtry languages, a single
            global instance of the <code class="function">gl_PerVertex</code> named block is available and
            its <code class="function">gl_Position</code> member is an output that receives the
            homogeneous vertex position. It may be written at any time during shader execution.
            The value written to <code class="function">gl_Position</code> will be used by primitive assembly,
            clipping, culling and other fixed functionality operations, if present, that operate on
            primitives after vertex processing has occurred.
        </p><p>
            In the tessellation control language, the <code class="function">gl_PerVertex</code> named block
            is used to construct an array, <code class="function">gl_out[]</code>, whose <code class="function">gl_Position</code>
            members hold the homogeneous control point position, which become available as inputs to the subsequent
            tessellation evaluation shader.
        </p><p>
            The value of <code class="function">gl_Position</code> (or the <code class="function">gl_Position</code> member of the <code class="function">gl_out[]</code>
            array, in the case of the tessellation control shader)
            is undefined after the vertex, tessellation control, and tessellation evaluation
            shading stages if the corresponding shader executable does
            not write to gl_Position. It is also undefined after the geometry processing stage if the geometry shader executable calls
            <a href="EmitVertex.xml"><span class="citerefentry"><span class="refentrytitle">EmitVertex</span></span></a> without having
            written <code class="function">gl_Position</code> since the last call to <a href="EmitVertex.xml"><span class="citerefentry"><span class="refentrytitle">EmitVertex</span></span></a>
            (or hasn't written it at all).
        </p><p>
            In the tessellation control, tessellation evaluation and geoemetry languages,
            the <code class="function">gl_PerVertex</code> named block is used to construct an array, <code class="function">gl_in[]</code>
            of per-vertex or per-control point inputs whose content represents the corresponding
            outputs written by the previous stage.
         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="versions"></a><h2>Version Support</h2><div class="informaltable"><table border="1"><colgroup><col align="left" /><col align="center" /><col align="center" /></colgroup><thead><tr><th align="left"><span class="bold"><strong>
                        Variable
                        </strong></span></th><th align="left"><span class="bold"><strong>
                        Version 1.10
                        </strong></span></th><th align="left"><span class="bold"><strong>
                        Version 1.20
                        </strong></span></th><th align="left"><span class="bold"><strong>
                        Version 1.30
                        </strong></span></th><th align="left"><span class="bold"><strong>
                        Version 1.40
                        </strong></span></th><th align="left"><span class="bold"><strong>
                        Version 1.50
                        </strong></span></th><th align="left"><span class="bold"><strong>
                        Version 3.30
                        </strong></span></th><th align="left"><span class="bold"><strong>
                        Version 4.00
                        </strong></span></th><th align="left"><span class="bold"><strong>
                        Version 4.10
                        </strong></span></th></tr><tr><th align="left">
                            gl_Position
                        </th><th align="center">
                            <span class="emphasis"><em>Y</em></span><sup>1</sup>  
                        </th><th align="center">
                            <span class="emphasis"><em>Y</em></span><sup>1</sup>  
                        </th><th align="center">
                            <span class="emphasis"><em>Y</em></span><sup>1</sup>  
                        </th><th align="center">
                            <span class="emphasis"><em>Y</em></span><sup>1</sup>  
                        </th><th align="center">
                            <span class="emphasis"><em>Y</em></span><sup>2</sup>  
                        </th><th align="center">
                            <span class="emphasis"><em>Y</em></span><sup>2</sup>  
                        </th><th align="center">
                            <span class="emphasis"><em>Y</em></span>  
                        </th><th align="center">
                            <span class="emphasis"><em>Y</em></span>  
                        </th></tr></thead></table></div><p>Versions 1.10 to 1.40 - vertex shader only.</p><p>Versions 1.50 to 3.30 - vertex and geometry shaders only.</p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
            <a href="gl_PointSize.xml"><span class="citerefentry"><span class="refentrytitle">gl_PointSize</span></span></a>, <a href="gl_ClipDistance.xml"><span class="citerefentry"><span class="refentrytitle">gl_ClipDistance</span></span></a>
        </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
            Copyright <span class="trademark"></span>© 2011 Khronos Group. 
            This material may be distributed subject to the terms and conditions set forth in 
            the Open Publication License, v 1.0, 8 June 1999.
            <a href="http://opencontent.org/openpub/" target="_top">http://opencontent.org/openpub/</a>.
        </p></div></div></body></html>
Commit	Line	Data
7faf1d71 AW	1	<?xml version="1.0" encoding="UTF-8"?>
	2	<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "xhtml1-transitional.dtd">
	3	<!-- saved from url=(0013)about:internet -->
	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>gl_Position - OpenGL Shading Language (GLSL)</title><meta name="generator" content="DocBook XSL Stylesheets V1.69.1" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="gl_Position"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>gl_Position — contains the position of the current vertex</p></div><div class="refsynopsisdiv"><h2>Declaration</h2><p>
	5	<code class="function">gl_Position</code> is a member of the <code class="function">gl_PerVertex</code>
	6	named block:
	7	</p><div class="funcsynopsis"><pre class="programlisting"> out gl_PerVertex {
	8	vec4 gl_Position;
	9	float gl_PointSize;
	10	float gl_ClipDistance[];
	11	};</pre></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
	12	In the vertex, tessellation evaluation and geoemtry languages, a single
	13	global instance of the <code class="function">gl_PerVertex</code> named block is available and
	14	its <code class="function">gl_Position</code> member is an output that receives the
	15	homogeneous vertex position. It may be written at any time during shader execution.
	16	The value written to <code class="function">gl_Position</code> will be used by primitive assembly,
	17	clipping, culling and other fixed functionality operations, if present, that operate on
	18	primitives after vertex processing has occurred.
	19	</p><p>
	20	In the tessellation control language, the <code class="function">gl_PerVertex</code> named block
	21	is used to construct an array, <code class="function">gl_out[]</code>, whose <code class="function">gl_Position</code>
	22	members hold the homogeneous control point position, which become available as inputs to the subsequent
	23	tessellation evaluation shader.
	24	</p><p>
	25	The value of <code class="function">gl_Position</code> (or the <code class="function">gl_Position</code> member of the <code class="function">gl_out[]</code>
	26	array, in the case of the tessellation control shader)
	27	is undefined after the vertex, tessellation control, and tessellation evaluation
	28	shading stages if the corresponding shader executable does
	29	not write to gl_Position. It is also undefined after the geometry processing stage if the geometry shader executable calls
	30	<a href="EmitVertex.xml"><span class="citerefentry"><span class="refentrytitle">EmitVertex</span></span></a> without having
	31	written <code class="function">gl_Position</code> since the last call to <a href="EmitVertex.xml"><span class="citerefentry"><span class="refentrytitle">EmitVertex</span></span></a>
	32	(or hasn't written it at all).
	33	</p><p>
	34	In the tessellation control, tessellation evaluation and geoemetry languages,
	35	the <code class="function">gl_PerVertex</code> named block is used to construct an array, <code class="function">gl_in[]</code>
	36	of per-vertex or per-control point inputs whose content represents the corresponding
	37	outputs written by the previous stage.
	38	</p></div><div class="refsect1" lang="en" xml:lang="en"><a id="versions"></a><h2>Version Support</h2><div class="informaltable"><table border="1"><colgroup><col align="left" /><col align="center" /><col align="center" /></colgroup><thead><tr><th align="left"><span class="bold"><strong>
	39	Variable
	40	</strong></span></th><th align="left"><span class="bold"><strong>
	41	Version 1.10
	42	</strong></span></th><th align="left"><span class="bold"><strong>
	43	Version 1.20
	44	</strong></span></th><th align="left"><span class="bold"><strong>
	45	Version 1.30
	46	</strong></span></th><th align="left"><span class="bold"><strong>
	47	Version 1.40
	48	</strong></span></th><th align="left"><span class="bold"><strong>
	49	Version 1.50
	50	</strong></span></th><th align="left"><span class="bold"><strong>
	51	Version 3.30
	52	</strong></span></th><th align="left"><span class="bold"><strong>
	53	Version 4.00
	54	</strong></span></th><th align="left"><span class="bold"><strong>
	55	Version 4.10
	56	</strong></span></th></tr><tr><th align="left">
	57	gl_Position
	58	</th><th align="center">
	59	<span class="emphasis"><em>Y</em></span><sup>1</sup>
	60	</th><th align="center">
	61	<span class="emphasis"><em>Y</em></span><sup>1</sup>
	62	</th><th align="center">
	63	<span class="emphasis"><em>Y</em></span><sup>1</sup>
	64	</th><th align="center">
65	<span class="emphasis"><em>Y</em></span><sup>1</sup>
66	</th><th align="center">
67	<span class="emphasis"><em>Y</em></span><sup>2</sup>
68	</th><th align="center">
69	<span class="emphasis"><em>Y</em></span><sup>2</sup>
70	</th><th align="center">
71	<span class="emphasis"><em>Y</em></span>
72	</th><th align="center">
73	<span class="emphasis"><em>Y</em></span>
74	</th></tr></thead></table></div><p>Versions 1.10 to 1.40 - vertex shader only.</p><p>Versions 1.50 to 3.30 - vertex and geometry shaders only.</p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
75	<a href="gl_PointSize.xml"><span class="citerefentry"><span class="refentrytitle">gl_PointSize</span></span></a>, <a href="gl_ClipDistance.xml"><span class="citerefentry"><span class="refentrytitle">gl_ClipDistance</span></span></a>
76	</p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
77	Copyright <span class="trademark"></span>© 2011 Khronos Group.
78	This material may be distributed subject to the terms and conditions set forth in
79	the Open Publication License, v 1.0, 8 June 1999.
80	<a href="http://opencontent.org/openpub/" target="_top">http://opencontent.org/openpub/</a>.
81	</p></div></div></body></html>