177 lines
10 KiB
XML
177 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="glBlitFramebuffer">
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<refentryinfo>
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<copyright>
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<year>2010-2013</year>
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<holder>Khronos Group</holder>
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</copyright>
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</refentryinfo>
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<refmeta>
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<refentrytitle>glBlitFramebuffer</refentrytitle>
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<manvolnum>3G</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>glBlitFramebuffer</refname>
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<refpurpose>copy a block of pixels from the read framebuffer to the draw framebuffer</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>glBlitFramebuffer</function></funcdef>
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<paramdef>GLint <parameter>srcX0</parameter></paramdef>
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<paramdef>GLint <parameter>srcY0</parameter></paramdef>
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<paramdef>GLint <parameter>srcX1</parameter></paramdef>
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<paramdef>GLint <parameter>srcY1</parameter></paramdef>
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<paramdef>GLint <parameter>dstX0</parameter></paramdef>
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<paramdef>GLint <parameter>dstY0</parameter></paramdef>
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<paramdef>GLint <parameter>dstX1</parameter></paramdef>
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<paramdef>GLint <parameter>dstY1</parameter></paramdef>
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<paramdef>GLbitfield <parameter>mask</parameter></paramdef>
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<paramdef>GLenum <parameter>filter</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>srcX0</parameter></term>
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<term><parameter>srcY0</parameter></term>
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<term><parameter>srcX1</parameter></term>
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<term><parameter>srcY1</parameter></term>
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<listitem>
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<para>
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Specify the bounds of the source rectangle within the read buffer of the read framebuffer.
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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>dstX0</parameter></term>
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<term><parameter>dstY0</parameter></term>
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<term><parameter>dstX1</parameter></term>
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<term><parameter>dstY1</parameter></term>
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<listitem>
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<para>
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Specify the bounds of the destination rectangle within the write buffer of the write framebuffer.
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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>mask</parameter></term>
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<listitem>
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<para>
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The bitwise OR of the flags indicating which buffers are to be copied. The allowed flags are
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<constant>GL_COLOR_BUFFER_BIT</constant>, <constant>GL_DEPTH_BUFFER_BIT</constant> and <constant>GL_STENCIL_BUFFER_BIT</constant>.
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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>filter</parameter></term>
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<listitem>
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<para>
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Specifies the interpolation to be applied if the image is stretched. Must be <constant>GL_NEAREST</constant> or <constant>GL_LINEAR</constant>.
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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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<function>glBlitFramebuffer</function> transfers a rectangle of pixel values from one region of the read framebuffer to another region in
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the draw framebuffer. <parameter>mask</parameter> is the bitwise OR of a number of values indicating which buffers are
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to be copied. The values are <constant>GL_COLOR_BUFFER_BIT</constant>, <constant>GL_DEPTH_BUFFER_BIT</constant>, and
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<constant>GL_STENCIL_BUFFER_BIT</constant>. The pixels corresponding to these buffers are copied from the source rectangle bounded by the
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locations (<parameter>srcX0</parameter>; <parameter>srcY0</parameter>) and (<parameter>srcX1</parameter>; <parameter>srcY1</parameter>)
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to the destination rectangle bounded by the locations (<parameter>dstX0</parameter>; <parameter>dstY0</parameter>) and
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(<parameter>dstX1</parameter>; <parameter>dstY1</parameter>). The lower bounds of the rectangle are inclusive, while the upper
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bounds are exclusive.
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</para>
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<para>
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The actual region taken from the read framebuffer is limited to the intersection of the source buffers being transferred, which may
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include the color buffer selected by the read buffer, the depth buffer, and/or the stencil buffer depending on mask. The actual region
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written to the draw framebuffer is limited to the intersection of the destination buffers being written, which may include multiple draw
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buffers, the depth buffer, and/or the stencil buffer depending on mask. Whether or not the source or destination regions are altered due
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to these limits, the scaling and offset applied to pixels being transferred is performed as though no such limits were present.
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</para>
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<para>
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If the sizes of the source and destination rectangles are not equal, <parameter>filter</parameter> specifies the interpolation method that
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will be applied to resize the source image , and must be <constant>GL_NEAREST</constant> or <constant>GL_LINEAR</constant>.
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<constant>GL_LINEAR</constant> is only a valid interpolation method for the color buffer. If <parameter>filter</parameter> is not
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<constant>GL_NEAREST</constant> and <parameter>mask</parameter> includes <constant>GL_DEPTH_BUFFER_BIT</constant> or
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<constant>GL_STENCIL_BUFFER_BIT</constant>, no data is transferred and a <constant>GL_INVALID_OPERATION</constant> error is generated.
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</para>
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<para>
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If <parameter>filter</parameter> is <constant>GL_LINEAR</constant> and the source rectangle would require sampling outside the bounds of
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the source framebuffer, values are read as if the <constant>GL_CLAMP_TO_EDGE</constant> texture wrapping mode were applied.
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</para>
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<para>
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When the color buffer is transferred, values are taken from the read buffer of the read framebuffer and written to each of the draw
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buffers of the draw framebuffer.
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</para>
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<para>
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If the source and destination rectangles overlap or are the same, and the read and draw buffers are the same, the result of the operation
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is undefined.
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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_OPERATION</constant> is generated if <parameter>mask</parameter> contains any of the <constant>GL_DEPTH_BUFFER_BIT</constant>
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or <constant>GL_STENCIL_BUFFER_BIT</constant> and <parameter>filter</parameter> is not <constant>GL_NEAREST</constant>.
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</para>
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<para>
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<constant>GL_INVALID_OPERATION</constant> is generated if <parameter>mask</parameter> contains <constant>GL_COLOR_BUFFER_BIT</constant>
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and any of the following conditions hold:
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<itemizedlist>
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<listitem>
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<para>The read buffer contains fixed-point or floating-point values and any draw buffer contains
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neither fixed-point nor floating-point values.</para>
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</listitem>
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<listitem>
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<para>The read buffer contains unsigned integer values and any draw buffer does not contain unsigned
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integer values.</para>
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</listitem>
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<listitem>
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<para>The read buffer contains signed integer values and any draw buffer does not contain signed integer values.</para>
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</listitem>
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</itemizedlist>
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</para>
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<para>
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<constant>GL_INVALID_OPERATION</constant> is generated if <parameter>mask</parameter> contains <constant>GL_DEPTH_BUFFER_BIT</constant> or
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<constant>GL_STENCIL_BUFFER_BIT</constant> and the source and destination depth and stencil formats do not match.
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</para>
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<para>
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<constant>GL_INVALID_OPERATION</constant> is generated if <parameter>filter</parameter> is <constant>GL_LINEAR</constant> and the read buffer
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contains integer data.
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</para>
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<para>
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<constant>GL_INVALID_OPERATION</constant> is generated if the value of <parameter>GL_SAMPLES</parameter> for the read and draw buffers is
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not identical.
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</para>
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<para>
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<constant>GL_INVALID_OPERATION</constant> is generated if <parameter>GL_SAMPLE_BUFFERS</parameter> for both read and draw buffers greater than
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zero and the dimensions of the source and destination rectangles is not identical.
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</para>
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<para>
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<constant>GL_INVALID_FRAMEBUFFER_OPERATION</constant> is generated if the objects bound to <constant>GL_DRAW_FRAMEBUFFER_BINDING</constant>
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or <constant>GL_READ_FRAMEBUFFER_BINDING</constant> are not framebuffer complete.
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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>glReadPixels</refentrytitle></citerefentry>
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<citerefentry><refentrytitle>glCheckFramebufferStatus</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glGenFramebuffers</refentrytitle></citerefentry>
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<citerefentry><refentrytitle>glBindFramebuffer</refentrytitle></citerefentry>
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<citerefentry><refentrytitle>glDeleteFramebuffers</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> 2010-2013 Khronos Group.
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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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