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<a name="Rectangles"></a>
<div class="header">
<p>
Next: <a href="Transforms.html#Transforms" accesskey="n" rel="next">Transforms</a>, Previous: <a href="Vectors.html#Vectors" accesskey="p" rel="prev">Vectors</a>, Up: <a href="Math.html#Math" accesskey="u" rel="up">Math</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index.html#Index" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<a name="Rectangles-1"></a>
<h4 class="subsection">4.2.2 Rectangles</h4>
<div class="example">
<pre class="example">(use-modules (sly math rect))
</pre></div>
<p>Rects are 2D axis-aligned bounding boxes. They are useful for
defining rectangular regions, such as the hitbox of a game entity, or
the viewport of a camera. Because rects are axis-aligned, they
provide a cheap means to perform simple collision detection.
</p>
<p>The <code><rect></code> type descriptor has been exposed for use with
Guile’s <code>(ice-9 match)</code> pattern matching module.
</p>
<dl>
<dt><a name="index-_003crect_003e"></a>Scheme Variable: <strong><rect></strong></dt>
<dd><p>Rectangle data type with fields <code>x</code>, <code>y</code>, <code>width</code>,
<code>height</code>, in that order.
</p></dd></dl>
<dl>
<dt><a name="index-make_002drect"></a>Scheme Procedure: <strong>make-rect</strong> <em><var>x</var> <var>y</var> <var>width</var> <var>height</var></em></dt>
<dd><p>Create a new rectangle with position (<var>x</var>, <var>y</var>), and
dimensions (<var>width</var>, <var>height</var>).
</p></dd></dl>
<dl>
<dt><a name="index-null_002drect"></a>Scheme Variable: <strong>null-rect</strong></dt>
<dd><p>Rectangle with <code>x</code>, <code>y</code>, <code>width</code>, and <code>height</code> of 0.
</p></dd></dl>
<dl>
<dt><a name="index-rect_003f"></a>Scheme Syntax: <strong>rect?</strong> <em><var>obj</var></em></dt>
<dd><p>Return <code>#t</code> if <var>obj</var> is a rectangle.
</p></dd></dl>
<dl>
<dt><a name="index-rect_002dx"></a>Scheme Syntax: <strong>rect-x</strong> <em><var>rect</var></em></dt>
<dd><p>Return the x coordinate of <var>rect</var>.
</p></dd></dl>
<dl>
<dt><a name="index-rect_002dy"></a>Scheme Syntax: <strong>rect-y</strong> <em><var>rect</var></em></dt>
<dd><p>Return the x coordinate of <var>rect</var>.
</p></dd></dl>
<dl>
<dt><a name="index-rect_002dwidth"></a>Scheme Syntax: <strong>rect-width</strong> <em><var>rect</var></em></dt>
<dd><p>Return the width of <var>rect</var>.
</p></dd></dl>
<dl>
<dt><a name="index-rect_002dheight"></a>Scheme Syntax: <strong>rect-height</strong> <em><var>rect</var></em></dt>
<dd><p>Return the height of <var>rect</var>.
</p></dd></dl>
<dl>
<dt><a name="index-rect_002dleft"></a>Scheme Procedure: <strong>rect-left</strong> <em><var>rect</var></em></dt>
<dd><p>Return the left-hand x coordinate of <var>rect</var>.
</p></dd></dl>
<dl>
<dt><a name="index-rect_002dright"></a>Scheme Procedure: <strong>rect-right</strong> <em><var>rect</var></em></dt>
<dd><p>Return the right-hand x coordinate of <var>rect</var>.
</p></dd></dl>
<dl>
<dt><a name="index-rect_002dtop"></a>Scheme Procedure: <strong>rect-top</strong> <em><var>rect</var></em></dt>
<dd><p>Return the top y coordinate of <var>rect</var>
</p></dd></dl>
<dl>
<dt><a name="index-rect_002dbottom"></a>Scheme Procedure: <strong>rect-bottom</strong> <em><var>rect</var></em></dt>
<dd><p>Return the bottom y coordinate of <var>rect</var>.
</p></dd></dl>
<dl>
<dt><a name="index-rect_002dtop_002dleft"></a>Scheme Procedure: <strong>rect-top-left</strong> <em><var>rect</var></em></dt>
<dd><p>Return the top-left corner of <var>rect</var>.
</p></dd></dl>
<dl>
<dt><a name="index-rect_002dtop_002dright"></a>Scheme Procedure: <strong>rect-top-right</strong> <em><var>rect</var></em></dt>
<dd><p>Return the top-right corner of <var>rect</var>.
</p></dd></dl>
<dl>
<dt><a name="index-rect_002dbottom_002dleft"></a>Scheme Procedure: <strong>rect-bottom-left</strong> <em><var>rect</var></em></dt>
<dt><a name="index-rect_002dposition"></a>Scheme Procedure: <strong>rect-position</strong> <em><var>rect</var></em></dt>
<dd><p>Return the bottom-left corner of <var>rect</var>
</p></dd></dl>
<dl>
<dt><a name="index-rect_002dbottom_002dright"></a>Scheme Procedure: <strong>rect-bottom-right</strong> <em><var>rect</var></em></dt>
<dd><p>Return the bottom-right corner of <var>rect</var>.
</p></dd></dl>
<dl>
<dt><a name="index-rect_002dcenter_002dx"></a>Scheme Procedure: <strong>rect-center-x</strong> <em><var>rect</var></em></dt>
<dd><p>Return the center x coordinate of <var>rect</var>.
</p></dd></dl>
<dl>
<dt><a name="index-rect_002dcenter_002dy"></a>Scheme Procedure: <strong>rect-center-y</strong> <em><var>rect</var></em></dt>
<dd><p>Return the center y coordinate of <var>rect</var>.
</p></dd></dl>
<dl>
<dt><a name="index-rect_002dcenter"></a>Scheme Procedure: <strong>rect-center</strong> <em><var>rect</var></em></dt>
<dd><p>Return the center of <var>rect</var>.
</p></dd></dl>
<dl>
<dt><a name="index-rect_002dhalf_002dwidth"></a>Scheme Procedure: <strong>rect-half-width</strong> <em><var>rect</var></em></dt>
<dd><p>Return the half width of <var>rect</var>.
</p></dd></dl>
<dl>
<dt><a name="index-rect_002dhalf_002dheight"></a>Scheme Procedure: <strong>rect-half-height</strong> <em><var>rect</var></em></dt>
<dd><p>Return the half height of <var>rect</var>.
</p></dd></dl>
<dl>
<dt><a name="index-rect_002dsize"></a>Scheme Procedure: <strong>rect-size</strong> <em><var>rect</var></em></dt>
<dd><p>Return the size of <var>rect</var>.
</p></dd></dl>
<dl>
<dt><a name="index-rect_002dmove"></a>Scheme Procedure: <strong>rect-move</strong> <em><var>rect</var> <var>v</var></em></dt>
<dt><a name="index-rect_002dmove-1"></a>Scheme Procedure: <strong>rect-move</strong> <em><var>rect</var> <var>x</var> <var>y</var></em></dt>
<dd><p>Create a new rectangle by moving <var>rect</var> by the given 2D vector
offset <var>v</var>, or the coordinates <var>x</var> and <var>y</var>.
</p></dd></dl>
<dl>
<dt><a name="index-rect_002dinflate"></a>Scheme Procedure: <strong>rect-inflate</strong> <em><var>rect</var> <var>size</var></em></dt>
<dt><a name="index-rect_002dinflate-1"></a>Scheme Procedure: <strong>rect-inflate</strong> <em><var>rect</var> <var>width</var> <var>height</var></em></dt>
<dd><p>Create a new rectangle by growing <var>rect</var> by the 2D vector
<var>size</var> (or <var>width</var> and <var>height</var>) without changing the
center point.
</p></dd></dl>
<dl>
<dt><a name="index-rect_002dunion"></a>Scheme Procedure: <strong>rect-union</strong> <em><var>rect1</var> <var>rect2</var></em></dt>
<dd><p>Create a new rectangle that covers the area of both <var>rect1</var> and
<var>rect2</var>.
</p></dd></dl>
<dl>
<dt><a name="index-rect_002dclip"></a>Scheme Procedure: <strong>rect-clip</strong> <em><var>rect1</var> <var>rect2</var></em></dt>
<dd><p>Create a new rectangle that is the overlapping region of <var>rect1</var>
and <var>rect2</var>. If the rects do not overlap, a rect of size 0 is
returned.
</p></dd></dl>
<dl>
<dt><a name="index-rect_002dclamp"></a>Scheme Procedure: <strong>rect-clamp</strong> <em><var>rect</var> <var>v</var></em></dt>
<dd><p>Return a new 2D vector by constraining <var>v</var> to the bounds of
<var>rect</var>.
</p></dd></dl>
<dl>
<dt><a name="index-rect_002dwithin_003f"></a>Scheme Procedure: <strong>rect-within?</strong> <em><var>rect1</var> <var>rect2</var></em></dt>
<dd><p>Return <code>#t</code> if <var>rect2</var> is completely within <var>rect1</var>.
</p></dd></dl>
<dl>
<dt><a name="index-rect_002dintersects_003f"></a>Scheme Procedure: <strong>rect-intersects?</strong> <em><var>rect1</var> <var>rect2</var></em></dt>
<dd><p>Return <code>#t</code> if <var>rect2</var> overlaps <var>rect1</var>.
</p></dd></dl>
<dl>
<dt><a name="index-rect_002dcontains_003f"></a>Scheme Procedure: <strong>rect-contains?</strong> <em><var>rect</var> <var>v</var></em></dt>
<dt><a name="index-rect_002dcontains_003f-1"></a>Scheme Procedure: <strong>rect-contains?</strong> <em><var>rect</var> <var>x</var> <var>y</var></em></dt>
<dd><p>Return <code>#t</code> if the 2D vector <var>v</var> (or the coordinates <var>x</var>
and <var>y</var>) is within <var>rect</var>.
</p></dd></dl>
<hr>
<div class="header">
<p>
Next: <a href="Transforms.html#Transforms" accesskey="n" rel="next">Transforms</a>, Previous: <a href="Vectors.html#Vectors" accesskey="p" rel="prev">Vectors</a>, Up: <a href="Math.html#Math" accesskey="u" rel="up">Math</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index.html#Index" title="Index" rel="index">Index</a>]</p>
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