258 lines
10 KiB
XML
258 lines
10 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
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"http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
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<refentry id="glUseProgram">
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<refmeta>
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<refentrytitle>glUseProgram</refentrytitle>
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<manvolnum>3G</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>glUseProgram</refname>
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<refpurpose>Installs a program object as part of current rendering state</refpurpose>
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</refnamediv>
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<refsynopsisdiv><title>C Specification</title>
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<funcsynopsis>
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<funcprototype>
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<funcdef>void <function>glUseProgram</function></funcdef>
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<paramdef>GLuint <parameter>program</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1 id="parameters"><title>Parameters</title>
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<variablelist>
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<varlistentry>
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<term><parameter>program</parameter></term>
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<listitem>
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<para>Specifies the handle of the program object
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whose executables are to be used as part of current
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rendering state.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1 id="description"><title>Description</title>
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<para><function>glUseProgram</function> installs the program
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object specified by <parameter>program</parameter> as part of
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current rendering state. One or more executables are created in
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a program object by successfully attaching shader objects to it
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with
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<citerefentry><refentrytitle>glAttachShader</refentrytitle></citerefentry>,
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successfully compiling the shader objects with
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<citerefentry><refentrytitle>glCompileShader</refentrytitle></citerefentry>,
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and successfully linking the program object with
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<citerefentry><refentrytitle>glLinkProgram</refentrytitle></citerefentry>.
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</para>
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<para>A program object will contain an executable that will run
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on the vertex processor if it contains one or more shader
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objects of type <constant>GL_VERTEX_SHADER</constant> that have
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been successfully compiled and linked. Similarly, a program
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object will contain an executable that will run on the fragment
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processor if it contains one or more shader objects of type
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<constant>GL_FRAGMENT_SHADER</constant> that have been
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successfully compiled and linked.</para>
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<para>Successfully installing an executable on a programmable
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processor will cause the corresponding fixed functionality of
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OpenGL to be disabled. Specifically, if an executable is
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installed on the vertex processor, the OpenGL fixed
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functionality will be disabled as follows.</para>
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<itemizedlist>
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<listitem>
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<para>The modelview matrix is not applied to vertex
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coordinates.</para>
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</listitem>
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<listitem>
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<para>The projection matrix is not applied to vertex
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coordinates.</para>
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</listitem>
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<listitem>
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<para>The texture matrices are not applied to texture
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coordinates.</para>
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</listitem>
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<listitem>
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<para>Normals are not transformed to eye
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coordinates.</para>
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</listitem>
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<listitem>
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<para>Normals are not rescaled or normalized.</para>
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</listitem>
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<listitem>
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<para>Normalization of
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<constant>GL_AUTO_NORMAL</constant> evaluated normals is
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not performed.</para>
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</listitem>
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<listitem>
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<para>Texture coordinates are not generated
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automatically.</para>
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</listitem>
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<listitem>
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<para>Per-vertex lighting is not performed.</para>
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</listitem>
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<listitem>
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<para>Color material computations are not
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performed.</para>
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</listitem>
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<listitem>
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<para>Color index lighting is not performed.</para>
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</listitem>
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<listitem>
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<para>This list also applies when setting the current
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raster position.</para>
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</listitem>
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</itemizedlist>
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<para>The executable that is installed on the vertex processor
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is expected to implement any or all of the desired functionality
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from the preceding list. Similarly, if an executable is
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installed on the fragment processor, the OpenGL fixed
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functionality will be disabled as follows.</para>
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<itemizedlist>
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<listitem>
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<para>Texture environment and texture functions are not
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applied.</para>
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</listitem>
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<listitem>
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<para>Texture application is not applied.</para>
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</listitem>
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<listitem>
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<para>Color sum is not applied.</para>
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</listitem>
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<listitem>
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<para>Fog is not applied.</para>
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</listitem>
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</itemizedlist>
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<para>Again, the fragment shader that is installed is expected
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to implement any or all of the desired functionality from the
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preceding list.</para>
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<para>While a program object is in use, applications are free to
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modify attached shader objects, compile attached shader objects,
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attach additional shader objects, and detach or delete shader
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objects. None of these operations will affect the executables
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that are part of the current state. However, relinking the
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program object that is currently in use will install the program
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object as part of the current rendering state if the link
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operation was successful (see
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<citerefentry><refentrytitle>glLinkProgram</refentrytitle></citerefentry>
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). If the program object currently in use is relinked
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unsuccessfully, its link status will be set to
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<constant>GL_FALSE</constant>, but the executables and
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associated state will remain part of the current state until a
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subsequent call to <function>glUseProgram</function> removes it
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from use. After it is removed from use, it cannot be made part
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of current state until it has been successfully relinked.</para>
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<para>If <parameter>program</parameter> contains shader objects
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of type <constant>GL_VERTEX_SHADER</constant> but it does not
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contain shader objects of type
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<constant>GL_FRAGMENT_SHADER</constant>, an executable will be
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installed on the vertex processor, but fixed functionality will
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be used for fragment processing. Similarly, if
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<parameter>program</parameter> contains shader objects of type
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<constant>GL_FRAGMENT_SHADER</constant> but it does not contain
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shader objects of type <constant>GL_VERTEX_SHADER</constant>, an
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executable will be installed on the fragment processor, but
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fixed functionality will be used for vertex processing. If
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<parameter>program</parameter> is 0, the programmable processors
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will be disabled, and fixed functionality will be used for both
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vertex and fragment processing.</para>
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</refsect1>
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<refsect1 id="notes"><title>Notes</title>
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<para><function>glUseProgram</function> is available only if the
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GL version is 2.0 or greater.</para>
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<para>While a program object is in use, the state that controls
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the disabled fixed functionality may also be updated using the
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normal OpenGL calls.</para>
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<para>Like display lists and texture objects, the name space for
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program objects may be shared across a set of contexts, as long
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as the server sides of the contexts share the same address
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space. If the name space is shared across contexts, any attached
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objects and the data associated with those attached objects are
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shared as well.</para>
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<para>Applications are responsible for providing the
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synchronization across API calls when objects are accessed from
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different execution threads.</para>
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</refsect1>
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<refsect1 id="errors"><title>Errors</title>
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<para><constant>GL_INVALID_VALUE</constant> is generated if
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<parameter>program</parameter> is neither 0 nor a value
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generated by OpenGL.</para>
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<para><constant>GL_INVALID_OPERATION</constant> is generated if
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<parameter>program</parameter> is not a program object.</para>
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<para><constant>GL_INVALID_OPERATION</constant> is generated if
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<parameter>program</parameter> could not be made part of current
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state.</para>
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<para><constant>GL_INVALID_OPERATION</constant> is generated if
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<function>glUseProgram</function> is executed between the
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execution of
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<citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry>
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and the corresponding execution of
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<citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.</para>
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</refsect1>
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<refsect1 id="associatedgets"><title>Associated Gets</title>
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<para><citerefentry><refentrytitle>glGet</refentrytitle></citerefentry>
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with the argument <constant>GL_CURRENT_PROGRAM</constant></para>
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<para><citerefentry><refentrytitle>glGetActiveAttrib</refentrytitle></citerefentry>
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with a valid program object and the index of an active attribute
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variable</para>
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<para><citerefentry><refentrytitle>glGetActiveUniform</refentrytitle></citerefentry>
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with a valid program object and the index of an active uniform
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variable</para>
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<para><citerefentry><refentrytitle>glGetAttachedShaders</refentrytitle></citerefentry>
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with a valid program object</para>
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<para><citerefentry><refentrytitle>glGetAttribLocation</refentrytitle></citerefentry>
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with a valid program object and the name of an attribute
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variable</para>
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<para><citerefentry><refentrytitle>glGetProgram</refentrytitle></citerefentry>
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with a valid program object and the parameter to be queried</para>
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<para><citerefentry><refentrytitle>glGetProgramInfoLog</refentrytitle></citerefentry>
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with a valid program object</para>
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<para><citerefentry><refentrytitle>glGetUniform</refentrytitle></citerefentry>
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with a valid program object and the location of a uniform
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variable</para>
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<para><citerefentry><refentrytitle>glGetUniformLocation</refentrytitle></citerefentry>
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with a valid program object and the name of a uniform
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variable</para>
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<para><citerefentry><refentrytitle>glIsProgram</refentrytitle></citerefentry></para>
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</refsect1>
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<refsect1 id="seealso"><title>See Also</title>
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<para><citerefentry><refentrytitle>gllAttachShader</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glBindAttribLocation</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glCompileShader</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glCreateProgram</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glDeleteProgram</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glDetachShader</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glLinkProgram</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glUniform</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glValidateProgram</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glVertexAttrib</refentrytitle></citerefentry></para>
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</refsect1>
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<refsect1 id="Copyright"><title>Copyright</title>
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<para>
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Copyright <trademark class="copyright"></trademark> 2003-2005 3Dlabs Inc. Ltd.
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This material may be distributed subject to the terms and conditions set forth in
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the Open Publication License, v 1.0, 8 June 1999.
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<ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
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</para>
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</refsect1>
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</refentry>
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