276 lines
14 KiB
XML
276 lines
14 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="glBitmap">
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<refmeta>
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<refmetainfo>
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<copyright>
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<year>1991-2006</year>
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<holder>Silicon Graphics, Inc.</holder>
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</copyright>
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</refmetainfo>
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<refentrytitle>glBitmap</refentrytitle>
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<manvolnum>3G</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>glBitmap</refname>
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<refpurpose>draw a bitmap</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>glBitmap</function></funcdef>
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<paramdef>GLsizei <parameter>width</parameter></paramdef>
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<paramdef>GLsizei <parameter>height</parameter></paramdef>
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<paramdef>GLfloat <parameter>xorig</parameter></paramdef>
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<paramdef>GLfloat <parameter>yorig</parameter></paramdef>
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<paramdef>GLfloat <parameter>xmove</parameter></paramdef>
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<paramdef>GLfloat <parameter>ymove</parameter></paramdef>
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<paramdef>const GLubyte * <parameter>bitmap</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<!-- eqn: ignoring delim $$ -->
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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>width</parameter></term>
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<term><parameter>height</parameter></term>
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<listitem>
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<para>
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Specify the pixel width and height of the bitmap image.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>xorig</parameter></term>
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<term><parameter>yorig</parameter></term>
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<listitem>
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<para>
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Specify the location of the origin in the bitmap image.
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The origin is measured from the lower left corner of the bitmap,
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with right and up being the positive axes.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>xmove</parameter></term>
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<term><parameter>ymove</parameter></term>
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<listitem>
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<para>
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Specify the <emphasis>x</emphasis> and <emphasis>y</emphasis> offsets to be added to the current raster position
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after the bitmap is drawn.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>bitmap</parameter></term>
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<listitem>
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<para>
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Specifies the address of the bitmap image.
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</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>
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A bitmap is a binary image.
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When drawn,
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the bitmap is positioned relative to the current raster position,
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and frame buffer pixels corresponding to 1's in the bitmap are
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written using the current raster color or index.
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Frame buffer pixels corresponding to 0's in the bitmap are not modified.
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</para>
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<para>
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<function>glBitmap</function> takes seven arguments.
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The first pair specifies the width and height of the bitmap image.
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The second pair specifies the location of the bitmap origin relative
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to the lower left corner of the bitmap image.
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The third pair of arguments specifies <emphasis>x</emphasis> and <emphasis>y</emphasis> offsets to be added
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to the current raster position after the bitmap has been drawn.
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The final argument is a pointer to the bitmap image itself.
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</para>
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<para>
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If a non-zero named buffer object is bound to the <constant>GL_PIXEL_UNPACK_BUFFER</constant> target
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(see <citerefentry><refentrytitle>glBindBuffer</refentrytitle></citerefentry>) while a bitmap image is
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specified, <parameter>bitmap</parameter> is treated as a byte offset into the buffer object's data store.
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</para>
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<para>
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The bitmap image is interpreted like image data for the <citerefentry><refentrytitle>glDrawPixels</refentrytitle></citerefentry>
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command,
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with <parameter>width</parameter> and <parameter>height</parameter> corresponding to the width and height arguments
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of that command,
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and with <emphasis>type</emphasis> set to <constant>GL_BITMAP</constant>
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and <emphasis>format</emphasis> set to <constant>GL_COLOR_INDEX</constant>.
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Modes specified using <citerefentry><refentrytitle>glPixelStore</refentrytitle></citerefentry> affect the
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interpretation of bitmap image data;
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modes specified using <citerefentry><refentrytitle>glPixelTransfer</refentrytitle></citerefentry> do not.
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</para>
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<para>
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If the current raster position is invalid, <function>glBitmap</function> is ignored.
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Otherwise,
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the lower left corner of the bitmap image is positioned at the window coordinates
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</para>
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<para>
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<inlineequation><mml:math>
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<!-- eqn: x sub w = \(lf x sub r - x sub o \(rf:-->
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<mml:mrow>
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<mml:msub><mml:mi mathvariant="italic">x</mml:mi>
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<mml:mi mathvariant="italic">w</mml:mi>
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</mml:msub>
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<mml:mo>=</mml:mo>
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<mml:mfenced open="⌊" close="⌋">
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<mml:mrow>
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<mml:msub><mml:mi mathvariant="italic">x</mml:mi>
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<mml:mi mathvariant="italic">r</mml:mi>
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</mml:msub>
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<mml:mo>-</mml:mo>
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<mml:msub><mml:mi mathvariant="italic">x</mml:mi>
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<mml:mi mathvariant="italic">o</mml:mi>
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</mml:msub>
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</mml:mrow>
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</mml:mfenced>
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</mml:mrow>
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</mml:math></inlineequation>
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</para>
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<para>
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<inlineequation><mml:math>
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<!-- eqn: y sub w = \(lf y sub r - y sub o \(rf:-->
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<mml:mrow>
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<mml:msub><mml:mi mathvariant="italic">y</mml:mi>
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<mml:mi mathvariant="italic">w</mml:mi>
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</mml:msub>
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<mml:mo>=</mml:mo>
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<mml:mfenced open="⌊" close="⌋">
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<mml:mrow>
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<mml:msub><mml:mi mathvariant="italic">y</mml:mi>
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<mml:mi mathvariant="italic">r</mml:mi>
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</mml:msub>
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<mml:mo>-</mml:mo>
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<mml:msub><mml:mi mathvariant="italic">y</mml:mi>
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<mml:mi mathvariant="italic">o</mml:mi>
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</mml:msub>
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</mml:mrow>
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</mml:mfenced>
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</mml:mrow>
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</mml:math></inlineequation>
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</para>
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<para>
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where
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<inlineequation><mml:math>
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<!-- eqn: ( x sub r , y sub r ):-->
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<mml:mfenced open="(" close=")">
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<mml:msub><mml:mi mathvariant="italic">x</mml:mi>
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<mml:mi mathvariant="italic">r</mml:mi>
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</mml:msub>
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<mml:msub><mml:mi mathvariant="italic">y</mml:mi>
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<mml:mi mathvariant="italic">r</mml:mi>
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</mml:msub>
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</mml:mfenced>
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</mml:math></inlineequation>
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is the raster position
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and
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<inlineequation><mml:math>
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<!-- eqn: ( x sub o , y sub o ):-->
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<mml:mfenced open="(" close=")">
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<mml:msub><mml:mi mathvariant="italic">x</mml:mi>
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<mml:mi mathvariant="italic">o</mml:mi>
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</mml:msub>
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<mml:msub><mml:mi mathvariant="italic">y</mml:mi>
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<mml:mi mathvariant="italic">o</mml:mi>
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</mml:msub>
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</mml:mfenced>
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</mml:math></inlineequation>
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is the bitmap origin.
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Fragments are then generated for each pixel corresponding to a 1 (one)
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in the bitmap image.
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These fragments are generated using the current raster <emphasis>z</emphasis> coordinate,
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color or color index, and current raster texture coordinates.
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They are then treated just as if they had been generated
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by a point, line, or polygon,
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including texture mapping,
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fogging,
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and all per-fragment operations such as alpha and depth testing.
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</para>
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<para>
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After the bitmap has been drawn,
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the <emphasis>x</emphasis> and <emphasis>y</emphasis> coordinates of the current raster position are offset by
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<parameter>xmove</parameter> and <parameter>ymove</parameter>.
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No change is made to the <emphasis>z</emphasis> coordinate of the current raster position,
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or to the current raster color, texture coordinates, or index.
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</para>
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</refsect1>
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<refsect1 id="notes"><title>Notes</title>
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<para>
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To set a valid raster position outside the viewport, first set a valid
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raster position inside the viewport, then call <function>glBitmap</function> with NULL
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as the <parameter>bitmap</parameter> parameter and with <parameter>xmove</parameter> and <parameter>ymove</parameter> set to
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the offsets of the new raster position. This technique is useful when
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panning an image around the viewport.
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</para>
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</refsect1>
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<refsect1 id="errors"><title>Errors</title>
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<para>
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<constant>GL_INVALID_VALUE</constant> is generated if <parameter>width</parameter> or <parameter>height</parameter> is negative.
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</para>
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<para>
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<constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the
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<constant>GL_PIXEL_UNPACK_BUFFER</constant> target and the buffer object's data store is currently mapped.
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</para>
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<para>
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<constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the
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<constant>GL_PIXEL_UNPACK_BUFFER</constant> target and the data would be unpacked from the buffer
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object such that the memory reads required would exceed the data store size.
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</para>
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<para>
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<constant>GL_INVALID_OPERATION</constant> is generated if <function>glBitmap</function>
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is executed between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> and the corresponding execution of
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<citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.
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</para>
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</refsect1>
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<refsect1 id="associatedgets"><title>Associated Gets</title>
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<para>
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<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_CURRENT_RASTER_POSITION</constant>
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</para>
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<para>
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<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_CURRENT_RASTER_COLOR</constant>
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</para>
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<para>
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<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_CURRENT_RASTER_SECONDARY_COLOR</constant>
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</para>
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<para>
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<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_CURRENT_RASTER_DISTANCE</constant>
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</para>
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<para>
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<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_CURRENT_RASTER_INDEX</constant>
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</para>
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<para>
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<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_CURRENT_RASTER_TEXTURE_COORDS</constant>
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</para>
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<para>
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<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_CURRENT_RASTER_POSITION_VALID</constant>
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</para>
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<para>
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<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PIXEL_UNPACK_BUFFER_BINDING</constant>
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</para>
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</refsect1>
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<refsect1 id="seealso"><title>See Also</title>
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<para>
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<citerefentry><refentrytitle>glBindBuffer</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glDrawPixels</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glPixelStore</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glPixelTransfer</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glRasterPos</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glWindowPos</refentrytitle></citerefentry>
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</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> 1991-2006
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Silicon Graphics, Inc. This document is licensed under the SGI
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Free Software B License. For details, see
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<ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
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</para>
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</refsect1>
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</refentry>
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