1<?xml version="1.0" encoding="UTF-8"?> 2<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN" 3 "http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd"> 4<refentry xml:base="" id="eglMakeCurrent"> 5 <refentryinfo> 6 <copyright> 7 <year>2003-2014</year> 8 <holder>The Khronos Group Inc.</holder> 9 </copyright> 10 </refentryinfo> 11 <refmeta> 12 <refentrytitle>eglMakeCurrent</refentrytitle> 13 <manvolnum>3G</manvolnum> 14 </refmeta> 15 <refnamediv> 16 <refname>eglMakeCurrent</refname> 17 <refpurpose> 18 attach an EGL rendering context to EGL surfaces 19 </refpurpose> 20 </refnamediv> 21 <refsynopsisdiv> 22 <title>C Specification</title> 23 <funcsynopsis> 24 <funcprototype> 25 <funcdef>EGLBoolean <function>eglMakeCurrent</function></funcdef> 26 <paramdef>EGLDisplay <parameter>display</parameter></paramdef> 27 <paramdef>EGLSurface <parameter>draw</parameter></paramdef> 28 <paramdef>EGLSurface <parameter>read</parameter></paramdef> 29 <paramdef>EGLContext <parameter>context</parameter></paramdef> 30 </funcprototype> 31 </funcsynopsis> 32 </refsynopsisdiv> 33 <refsect1 id="parameters"><title>Parameters</title> 34 <variablelist> 35 <varlistentry> 36 <term><parameter>display</parameter></term> 37 <listitem> 38 <para>Specifies the <acronym>EGL</acronym> display connection.</para> 39 </listitem> 40 </varlistentry> 41 <varlistentry> 42 <term><parameter>draw</parameter></term> 43 <listitem> 44 <para>Specifies the <acronym>EGL</acronym> draw surface.</para> 45 </listitem> 46 </varlistentry> 47 <varlistentry> 48 <term><parameter>read</parameter></term> 49 <listitem> 50 <para>Specifies the <acronym>EGL</acronym> read surface.</para> 51 </listitem> 52 </varlistentry> 53 <varlistentry> 54 <term><parameter>context</parameter></term> 55 <listitem> 56 <para>Specifies the <acronym>EGL</acronym> rendering context 57 to be attached to the surfaces. 58 </para> 59 </listitem> 60 </varlistentry> 61 </variablelist> 62 </refsect1> 63 <refsect1 id="description"><title>Description</title> 64 <para> 65 <function>eglMakeCurrent</function> binds <parameter>context</parameter> 66 to the current rendering thread and to the <parameter>draw</parameter> 67 and <parameter>read</parameter> surfaces. <parameter>draw</parameter> 68 is used for all GL operations except for any pixel data read back 69 (<citerefentry><refentrytitle>glReadPixels</refentrytitle></citerefentry>, 70 <citerefentry><refentrytitle>glCopyTexImage2D</refentrytitle></citerefentry>, and 71 <citerefentry><refentrytitle>glCopyTexSubImage2D</refentrytitle></citerefentry>), 72 which is taken from the frame buffer values of 73 <parameter>read</parameter>. 74 </para> 75 <para> 76 If the calling thread has already a current rendering context, that 77 context is flushed and marked as no longer current. 78 </para> 79 <para> 80 The first time that <parameter>context</parameter> is made current, 81 the viewport and scissor dimensions are set to the size of the 82 <parameter>draw</parameter> surface. The viewport and 83 scissor are not modified when <parameter>context</parameter> is 84 subsequently made current. 85 </para> 86 <para> 87 To release the current context without assigning a new one, call 88 <function>eglMakeCurrent</function> with <parameter>draw</parameter> 89 and <parameter>read</parameter> set to 90 <constant>EGL_NO_SURFACE</constant> and <parameter>context</parameter> 91 set to <constant>EGL_NO_CONTEXT</constant>. 92 </para> 93 <para> 94 Use 95 <citerefentry><refentrytitle>eglGetCurrentContext</refentrytitle></citerefentry>, 96 <citerefentry><refentrytitle>eglGetCurrentDisplay</refentrytitle></citerefentry>, and 97 <citerefentry><refentrytitle>eglGetCurrentSurface</refentrytitle></citerefentry> 98 to query the current rendering context and associated display connection and surfaces. 99 </para> 100 </refsect1> 101 <refsect1 id="errors"><title>Errors</title> 102 <para> 103 <constant>EGL_FALSE</constant> is returned on failure, 104 <constant>EGL_TRUE</constant> otherwise. If <constant>EGL_FALSE</constant> 105 is returned, the previously current rendering context and 106 surfaces (if any) remain unchanged. 107 </para> 108 <para> 109 <constant>EGL_BAD_DISPLAY</constant> is generated if 110 <parameter>display</parameter> is not an EGL display connection. 111 </para> 112 <para> 113 <constant>EGL_NOT_INITIALIZED</constant> is generated if 114 <parameter>display</parameter> has not been initialized. 115 </para> 116 <para> 117 <constant>EGL_BAD_SURFACE</constant> is generated if 118 <parameter>draw</parameter> or <parameter>read</parameter> is not an 119 EGL surface. 120 </para> 121 <para> 122 <constant>EGL_BAD_CONTEXT</constant> is generated if 123 <parameter>context</parameter> is not an EGL rendering context. 124 </para> 125 <para> 126 <constant>EGL_BAD_MATCH</constant> is generated if 127 <parameter>draw</parameter> or 128 <parameter>read</parameter> 129 are not compatible with 130 <parameter>context</parameter>, or if 131 <parameter>context</parameter> is set to 132 <constant>EGL_NO_CONTEXT</constant> and 133 <parameter>draw</parameter> or 134 <parameter>read</parameter> 135 are not set to 136 <constant>EGL_NO_SURFACE</constant>, or if 137 <parameter>draw</parameter> or 138 <parameter>read</parameter> are set to 139 <constant>EGL_NO_SURFACE</constant> and 140 <parameter>context</parameter> is not set to 141 <constant>EGL_NO_CONTEXT</constant>. 142 </para> 143 <para> 144 <constant>EGL_BAD_ACCESS</constant> is generated if 145 <parameter>context</parameter> 146 is current to some other thread. 147 </para> 148 <para> 149 <constant>EGL_BAD_NATIVE_PIXMAP</constant> may be generated if 150 a native pixmap underlying either 151 <parameter>draw</parameter> or 152 <parameter>read</parameter> 153 is no longer valid. 154 </para> 155 <para> 156 <constant>EGL_BAD_NATIVE_WINDOW</constant> may be generated if 157 a native window underlying either 158 <parameter>draw</parameter> or 159 <parameter>read</parameter> 160 is no longer valid. 161 </para> 162 <para> 163 <constant>EGL_BAD_CURRENT_SURFACE</constant> is generated if 164 the previous context has unflushed commands and the previous surface 165 is no longer valid. 166 </para> 167 <para> 168 <constant>EGL_BAD_ALLOC</constant> may be generated if 169 allocation of ancillary buffers for <parameter>draw</parameter> or 170 <parameter>read</parameter> were delayed until 171 <function>eglMakeCurrent</function> is called, and there are not 172 enough resources to allocate them. 173 </para> 174 <para> 175 <constant>EGL_CONTEXT_LOST</constant> is generated if a power management 176 event has occurred. The application must destroy all contexts and 177 reinitialise OpenGL ES state and objects to continue rendering. 178 </para> 179 </refsect1> 180 <refsect1 id="seealso"><title>See Also</title> 181 <para> 182 <citerefentry><refentrytitle>glReadPixels</refentrytitle></citerefentry>, 183 <citerefentry><refentrytitle>glCopyTexImage2D</refentrytitle></citerefentry>, 184 <citerefentry><refentrytitle>glCopyTexSubImage2D</refentrytitle></citerefentry>, 185 <citerefentry><refentrytitle>eglCreateContext</refentrytitle></citerefentry>, 186 <citerefentry><refentrytitle>eglCreatePbufferSurface</refentrytitle></citerefentry>, 187 <citerefentry><refentrytitle>eglCreatePixmapSurface</refentrytitle></citerefentry>, 188 <citerefentry><refentrytitle>eglCreateWindowSurface</refentrytitle></citerefentry>, 189 <citerefentry><refentrytitle>eglGetCurrentContext</refentrytitle></citerefentry>, 190 <citerefentry><refentrytitle>eglGetCurrentDisplay</refentrytitle></citerefentry>, 191 <citerefentry><refentrytitle>eglGetCurrentSurface</refentrytitle></citerefentry>, 192 <citerefentry><refentrytitle>eglGetDisplay</refentrytitle></citerefentry>, 193 <citerefentry><refentrytitle>eglInitialize</refentrytitle></citerefentry> 194 </para> 195 </refsect1> 196 <refsect3 id="Copyright"><title></title> 197 <!-- Content included from copyright.inc.xsl --> 198 <imageobject> 199 <imagedata fileref="KhronosLogo.jpg" format="jpg" /> 200 </imageobject> 201 <para /> 202 </refsect3> 203</refentry> 204
