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<span id="Textures"></span><div class="header">
<p>
Next: <a href="Sprites.html" accesskey="n" rel="next">Sprites</a>, Previous: <a href="Colors.html" accesskey="p" rel="prev">Colors</a>, Up: <a href="Graphics.html" accesskey="u" rel="up">Graphics</a> [<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="Textures-1"></span><h4 class="subsection">5.3.2 Textures</h4>
<p>Textures are essentially images: a 2D grid of color values. However,
this is a great simplification. Textures can be used to store any
kind of data that can be encoded into color channels. The
<code>(chickadee graphics texture)</code> module provides an interface for
working with texture objects.
</p>
<dl>
<dt id="index-load_002dimage">Procedure: <strong>load-image</strong> <em>file [#:min-filter nearest] [#:mag-filter nearest] [#:wrap-s repeat] [#:wrap-t repeat] [#:transparent-color]</em></dt>
<dd>
<p>Load the image data from <var>file</var> and return a new texture object.
</p>
<p><var>min-filter</var> and <var>mag-filter</var> describe the method that should
be used for minification and magnification when rendering,
respectively. Possible values are <code>nearest</code> and <code>linear</code>.
</p>
<p><var>wrap-s</var> and <var>wrap-t</var> describe how to interpret texture
coordinates that are greater than <code>1.0</code>. Possible values are
<code>repeat</code>, <code>mirrored-repeat</code>, <code>clamp</code>,
<code>clamp-to-border</code>, and <code>clamp-to-edge</code>.
</p>
<p>For color-keyed images (images where a specific color should be made
transparent), specify the appropriate <var>transparent-color</var>.
</p>
</dd></dl>
<dl>
<dt id="index-texture_003f">Procedure: <strong>texture?</strong> <em>obj</em></dt>
<dd><p>Return <code>#t</code> if <var>obj</var> is a texture.
</p></dd></dl>
<dl>
<dt id="index-texture_002dregion_003f">Procedure: <strong>texture-region?</strong> <em>obj</em></dt>
<dd><p>Return <code>#t</code> if <var>obj</var> is a texture region.
</p></dd></dl>
<dl>
<dt id="index-texture_002dparent">Procedure: <strong>texture-parent</strong> <em>texture</em></dt>
<dd><p>If <var>texture</var> is a texture region, return the full texture that it
is based upon. Otherwise, return <code>#f</code>.
</p></dd></dl>
<dl>
<dt id="index-texture_002dmin_002dfilter">Procedure: <strong>texture-min-filter</strong> <em>texture</em></dt>
<dd><p>Return the minification filter for <var>texture</var>, either
<code>nearest</code> or <code>linear</code>.
</p></dd></dl>
<dl>
<dt id="index-texture_002dmag_002dfilter">Procedure: <strong>texture-mag-filter</strong> <em>texture</em></dt>
<dd><p>Return the magnification filter for <var>texture</var>, either
<code>nearest</code> or <code>linear</code>.
</p></dd></dl>
<dl>
<dt id="index-texture_002dwrap_002ds">Procedure: <strong>texture-wrap-s</strong> <em>texture</em></dt>
<dd><p>Return the method used for wrapping texture coordinates along the X
axis for <var>texture</var>.
</p>
<p>Possible wrapping methods:
</p><ul>
<li> <code>repeat</code>
</li><li> <code>clamp</code>
</li><li> <code>clamp-to-border</code>
</li><li> <code>clamp-to-edge</code>
</li></ul>
</dd></dl>
<dl>
<dt id="index-texture_002dwrap_002dt">Procedure: <strong>texture-wrap-t</strong> <em>texture</em></dt>
<dd><p>Return the method used for wrapping texture coordinates along the Y
axis for <var>texture</var>.
</p></dd></dl>
<dl>
<dt id="index-texture_002dwidth">Procedure: <strong>texture-width</strong> <em>texture</em></dt>
<dd><p>Return the width of <var>texture</var> in pixels.
</p></dd></dl>
<dl>
<dt id="index-texture_002dheight">Procedure: <strong>texture-height</strong> <em>texture</em></dt>
<dd><p>Return the height of <var>texture</var> in pixels.
</p></dd></dl>
<dl>
<dt id="index-current_002dtexture_002d0">Procedure: <strong>current-texture-0</strong></dt>
<dd><p>Return the current texture associated with texture unit 0 on the GPU.
</p></dd></dl>
<dl>
<dt id="index-current_002dtexture_002d1">Procedure: <strong>current-texture-1</strong></dt>
<dd><p>Return the current texture associated with texture unit 1 on the GPU.
</p></dd></dl>
<dl>
<dt id="index-current_002dtexture_002d2">Procedure: <strong>current-texture-2</strong></dt>
<dd><p>Return the current texture associated with texture unit 2 on the GPU.
</p></dd></dl>
<dl>
<dt id="index-current_002dtexture_002d3">Procedure: <strong>current-texture-3</strong></dt>
<dd><p>Return the current texture associated with texture unit 3 on the GPU.
</p></dd></dl>
<dl>
<dt id="index-current_002dtexture_002d4">Procedure: <strong>current-texture-4</strong></dt>
<dd><p>Return the current texture associated with texture unit 4 on the GPU.
</p></dd></dl>
<dl>
<dt id="index-g_003atexture_002d0">Variable: <strong>g:texture-0</strong></dt>
<dd><p>Render state for texture unit 0 (see <a href="Rendering-Engine.html">Rendering Engine</a>.)
</p></dd></dl>
<dl>
<dt id="index-g_003atexture_002d1">Variable: <strong>g:texture-1</strong></dt>
<dd><p>Render state for texture unit 1 (see <a href="Rendering-Engine.html">Rendering Engine</a>.)
</p></dd></dl>
<dl>
<dt id="index-g_003atexture_002d2">Variable: <strong>g:texture-2</strong></dt>
<dd><p>Render state for texture unit 2 (see <a href="Rendering-Engine.html">Rendering Engine</a>.)
</p></dd></dl>
<dl>
<dt id="index-g_003atexture_002d3">Variable: <strong>g:texture-3</strong></dt>
<dd><p>Render state for texture unit 3 (see <a href="Rendering-Engine.html">Rendering Engine</a>.)
</p></dd></dl>
<dl>
<dt id="index-g_003atexture_002d4">Variable: <strong>g:texture-4</strong></dt>
<dd><p>Render state for texture unit 4 (see <a href="Rendering-Engine.html">Rendering Engine</a>.)
</p></dd></dl>
<span id="Tile-Atlases"></span><h4 class="subsubsection">5.3.2.1 Tile Atlases</h4>
<p>It is common practice to combine multiple bitmap images into a single
texture, known as a “tile atlas” or “tile set”, because it is more
efficient to render many regions of a large texture than it is to
render a bunch of small textures. Chickadee provides a tile atlas
data type for collecting texture regions into a single vector.
</p>
<dl>
<dt id="index-split_002dtexture">Procedure: <strong>split-texture</strong> <em>texture tile-width tile-height [#:margin 0] [#:spacing 0]</em></dt>
<dd>
<p>Return a new texture atlas that splits <var>texture</var> into a grid of
<var>tile-width</var> by <var>tile-height</var> rectangles. Optionally, each
tile may have <var>spacing</var> pixels of horizontal and vertical space
between surrounding tiles and the entire image may have <var>margin</var>
pixels of empty space around its border.
</p>
<p>This type of texture atlas layout is very common for 2D tile maps.
See <a href="Tile-Maps.html">Tile Maps</a> for more information.
</p></dd></dl>
<dl>
<dt id="index-load_002dtileset">Procedure: <strong>load-tileset</strong> <em>file-name tile-width tile-height [#:margin 0] [#:spacing 0] [#:min-filter nearest] [#:mag-filter nearest] [#:wrap-s repeat] [#:wrap-t repeat] [#:transparent-color]</em></dt>
<dd>
<p>Return a new texture atlas that splits the texture loaded from the
file <var>file-name</var> into a grid of <var>tile-width</var> by
<var>tile-height</var> rectangles. See <code>load-image</code> and
<code>split-texture</code> for information about all keyword arguments.
</p></dd></dl>
<dl>
<dt id="index-texture_002datlas_003f">Procedure: <strong>texture-atlas?</strong> <em>obj</em></dt>
<dd><p>Return <code>#t</code> if <var>obj</var> is a texture atlas.
</p></dd></dl>
<dl>
<dt id="index-texture_002datlas_002dtexture">Procedure: <strong>texture-atlas-texture</strong> <em>atlas</em></dt>
<dd><p>Return the texture that all texture regions in <var>atlas</var> have been created from.
</p></dd></dl>
<dl>
<dt id="index-texture_002datlas_002dref">Procedure: <strong>texture-atlas-ref</strong> <em>atlas index</em></dt>
<dd><p>Return the texture region in <var>atlas</var> at <var>index</var>.
</p></dd></dl>
<span id="Cube-Maps"></span><h4 class="subsubsection">5.3.2.2 Cube Maps</h4>
<p>A cube map is a special type of texture composed of 6 images that can
be thought of as forming the 6 faces of a cube. See <a href="Skyboxes.html">Skyboxes</a> for a
practical use of cube maps.
</p>
<dl>
<dt id="index-load_002dcube_002dmap">Procedure: <strong>load-cube-map</strong> <em>#:right #:left #:top #:bottom #:front #:back [#:min-filter linear-mipmap-linear] [#:mag-filter linear]</em></dt>
<dd>
<p>Return a new cube map that uses the image data in the files
<var>right</var>, <var>left</var>, <var>top</var>, <var>bottom</var>, <var>front</var>, and
<var>back</var> for the 6 faces of the cube.
</p></dd></dl>
<dl>
<dt id="index-cube_002dmap_003f">Procedure: <strong>cube-map?</strong> <em>obj</em></dt>
<dd><p>Return <code>#t</code> if <var>obj</var> is a cube map.
</p></dd></dl>
<hr />
<div class="header">
<p>
Next: <a href="Sprites.html" accesskey="n" rel="next">Sprites</a>, Previous: <a href="Colors.html" accesskey="p" rel="prev">Colors</a>, Up: <a href="Graphics.html" accesskey="u" rel="up">Graphics</a> [<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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