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* Chickadee: (chickadee).     Game programming toolkit for Guile.

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<span id="Viewports"></span><div class="header">
<p>
Next: <a href="Rendering-Engine.html" accesskey="n" rel="next">Rendering Engine</a>, Previous: <a href="Framebuffers.html" accesskey="p" rel="prev">Framebuffers</a>, Up: <a href="Graphics.html" accesskey="u" rel="up">Graphics</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index.html" title="Index" rel="index">Index</a>]</p>
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<hr>
<span id="Viewports-1"></span><h4 class="subsection">2.3.11 Viewports</h4>

<p>A viewport represents a subset of the screen (or framebuffer).  When
rendering a frame, the resulting image will only appear within that
viewport.  These aren&rsquo;t often needed, and Chickadee&rsquo;s default viewport
occupies the entire screen, but there are certain situations where
they are useful.  For example, a split-screen multiplayer game may
render to two different viewports, each occupying a different half of
the screen.  For information about how to set the current viewport,
see <code>with-viewport</code> in <a href="Rendering-Engine.html">Rendering Engine</a>.
</p>
<p>The <code>(chickadee graphics viewport)</code> module provides the following
API:
</p>
<dl>
<dt id="index-make_002dviewport">Procedure: <strong>make-viewport</strong> <em>x y width height                                  [#:clear-color] [#:clear-flags]</em></dt>
<dd>
<p>Create a viewport that covers an area of the window starting from
coordinates (<var>x</var>, <var>y</var>) and spanning <var>width</var> <code>x</code>
<var>height</var> pixels.  Fill the viewport with <var>clear-color</var> when
clearing the screen.  Clear the buffers denoted by the list of symbols
in <var>clear-flags</var>.
</p>
<p>Possible values for <var>clear-flags</var> are <var>color-buffer</var>,
<var>depth-buffer</var>, <var>accum-buffer</var>, and <var>stencil-buffer</var>.
</p></dd></dl>

<dl>
<dt id="index-viewport_003f">Procedure: <strong>viewport?</strong> <em>obj</em></dt>
<dd><p>Return <code>#t</code> if <var>obj</var> is a viewport.
</p></dd></dl>

<dl>
<dt id="index-viewport_002dx">Procedure: <strong>viewport-x</strong> <em>viewport</em></dt>
<dd><p>Return the left edge of <var>viewport</var>.
</p></dd></dl>

<dl>
<dt id="index-viewport_002dy">Procedure: <strong>viewport-y</strong> <em>viewport</em></dt>
<dd><p>Return the bottom edge of <var>viewport</var>.
</p></dd></dl>

<dl>
<dt id="index-viewport_002dwidth">Procedure: <strong>viewport-width</strong> <em>viewport</em></dt>
<dd><p>Return the width of <var>viewport</var>.
</p></dd></dl>

<dl>
<dt id="index-viewport_002dheight">Procedure: <strong>viewport-height</strong> <em>viewport</em></dt>
<dd><p>Return the height of <var>viewport</var>.
</p></dd></dl>

<dl>
<dt id="index-viewport_002dclear_002dcolor">Procedure: <strong>viewport-clear-color</strong> <em>viewport</em></dt>
<dd><p>Return the clear color for <var>viewport</var>.
</p></dd></dl>

<dl>
<dt id="index-viewport_002dclear_002dflags">Procedure: <strong>viewport-clear-flags</strong> <em>viewport</em></dt>
<dd><p>Return the list of clear flags for <var>viewport</var>.
</p></dd></dl>




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