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<concept xml:lang="en" id="GUID-15737F8C-2803-5B50-9D53-2DF79FAB76B1"><title>What API extensions are supported?</title><shortdesc>OpenGL ES implementations can expose implementation-specific functionality by use of the standard extension mechanisms. The implementer controls this by modifying the files <filepath>glextplatform.h</filepath> and <filepath>gl2extplatform.h</filepath> for 1.x and 2.0 respectively. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody><p> <b>Variant</b>: <xref href="GUID-D93978BE-11A3-5CE3-B110-1DEAA5AD566C.dita">ScreenPlay</xref> and <xref href="GUID-F64E6551-670E-5E12-8103-DE504D3EC94F.dita">non-ScreenPlay</xref>. <b>Target audience</b>: Device creators. </p> <p>Extensions are defined in <filepath>glext.h</filepath> and <filepath>gl2ext.h</filepath> for OpenGL ES 1.x and 2.0 respectively. Each extension is defined based upon its <codeph>#define</codeph> guard. For example, the OpenGL ES 2.0 extension "<xref href="GUID-FA00ABDB-B1B6-3112-96E5-605286AD643D.dita"><apiname>GL_ETC1_RGB8_OES</apiname></xref> " is guarded by the <codeph>#define</codeph> "<xref href="GUID-12DE78D7-12E3-3F05-A145-7C29E2EE97A4.dita"><apiname>GL_OES_compressed_ETC1_RGB8_texture</apiname></xref> " in <filepath>gl2ext.h</filepath>. </p> <p>By defining "<codeph>GL_OES_compressed_ETC1_RGB8_texture</codeph> " in <filepath>gl2extplatform.h</filepath>, the extension <codeph>GL_ETC1_RGB8_OES</codeph> is disabled in <filepath>gl2ext.h</filepath>. </p> </conbody><related-links><link href="GUID-7DD1BC7B-B3F7-515D-8DC8-B699B947B434.dita"><linktext>OpenGL ES Porting
                Guide</linktext> </link> <link href="GUID-90A4BDE2-839A-5A37-ACAA-EB33FE39DE54.dita"><linktext>OpenGL ES Variability
                Choices</linktext> </link> <link href="GUID-12D5C140-DFDA-549B-9CCF-EF7488B832AE.dita"><linktext>OpenGLES Interface Overview</linktext> </link> </related-links></concept>