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<span id="Meshes"></span><div class="header">
<p>
Next: <a href="Buffers.html" accesskey="n" rel="next">Buffers</a>, Previous: <a href="Skyboxes.html" accesskey="p" rel="prev">Skyboxes</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="Meshes-1"></span><h4 class="subsection">5.3.11 Meshes</h4>
<p>The <code>(chickadee graphics mesh)</code> modules provides procedures for
programmatically creating 3D objects (to load 3D models from a file on
disk, see <a href="#Meshes">Meshes</a>.)
</p>
<span id="Materials"></span><h4 class="subsubsection">5.3.11.1 Materials</h4>
<p>Before we talk about meshes themselves, let’s discuss “materials.”
Materials control the appearance of 3D objects. Whether an object
appears like a rough rock, a smooth and shiny metal, etc. depends on
the material that is applied to it. Different types of materials use
different lighting models. Chickadee supports two lighting models:
The classic Blinn-Phong model and a more modern physically based
rendering (PBR) model.
</p>
<p>All materials share some common data:
</p>
<dl>
<dt id="index-material_003f">Procedure: <strong>material?</strong> <em>obj</em></dt>
<dd><p>Return <code>#t</code> if <var>obj</var> is a material.
</p></dd></dl>
<dl>
<dt id="index-material_002dname">Procedure: <strong>material-name</strong> <em>material</em></dt>
<dd><p>Return the name of <var>material</var>.
</p></dd></dl>
<dl>
<dt id="index-material_002dshader">Procedure: <strong>material-shader</strong> <em>material</em></dt>
<dd><p>Return the shader of <var>material</var>.
</p></dd></dl>
<dl>
<dt id="index-material_002dblend_002dmode">Procedure: <strong>material-blend-mode</strong> <em>material</em></dt>
<dd><p>Return the blend mode of <var>material</var>.
</p></dd></dl>
<dl>
<dt id="index-material_002dpolygon_002dmode">Procedure: <strong>material-polygon-mode</strong> <em>material</em></dt>
<dd><p>Return the polygon mode of <var>material</var>.
</p></dd></dl>
<dl>
<dt id="index-material_002dcull_002dface_002dmode">Procedure: <strong>material-cull-face-mode</strong> <em>material</em></dt>
<dd><p>Return the cull face mode of <var>material</var>.
</p></dd></dl>
<dl>
<dt id="index-material_002ddepth_002dtest">Procedure: <strong>material-depth-test</strong> <em>material</em></dt>
<dd><p>Return the depth test of <var>material</var>.
</p></dd></dl>
<dl>
<dt id="index-material_002dstencil_002dtest">Procedure: <strong>material-stencil-test</strong> <em>material</em></dt>
<dd><p>Return the stencil test of <var>material</var>.
</p></dd></dl>
<dl>
<dt id="index-material_002dmultisample_003f">Procedure: <strong>material-multisample?</strong> <em>material</em></dt>
<dd><p>Return <code>#t</code> if <var>material</var> uses multisampling.
</p></dd></dl>
<p>Materials support 5 textures. What each texture is used for depends
on the lighting model.
</p>
<dl>
<dt id="index-material_002dtexture_002d0">Procedure: <strong>material-texture-0</strong> <em>material</em></dt>
<dd><p>Return the first texture of <var>material</var>.
</p></dd></dl>
<dl>
<dt id="index-material_002dtexture_002d1">Procedure: <strong>material-texture-1</strong> <em>material</em></dt>
<dd><p>Return the second texture of <var>material</var>.
</p></dd></dl>
<dl>
<dt id="index-material_002dtexture_002d2">Procedure: <strong>material-texture-2</strong> <em>material</em></dt>
<dd><p>Return the third texture of <var>material</var>.
</p></dd></dl>
<dl>
<dt id="index-material_002dtexture_002d3">Procedure: <strong>material-texture-3</strong> <em>material</em></dt>
<dd><p>Return the fourth texture of <var>material</var>.
</p></dd></dl>
<dl>
<dt id="index-material_002dtexture_002d4">Procedure: <strong>material-texture-4</strong> <em>material</em></dt>
<dd><p>Return the fifth texture of <var>material</var>.
</p></dd></dl>
<p>For all data that is specific to the lighting model, materials have a
“properties” field.
</p>
<dl>
<dt id="index-material_002dproperties">Procedure: <strong>material-properties</strong> <em>material</em></dt>
<dd><p>Return the lighting model specific properties of <var>material</var>.
</p></dd></dl>
<span id="Blinn_002dPhong-Materials"></span><h4 class="subsubsection">5.3.11.2 Blinn-Phong Materials</h4>
<p>The <code>(chickadee graphics phong)</code> module has the Blinn-Phong
lighting model:
</p>
<dl>
<dt id="index-make_002dphong_002dmaterial">Procedure: <strong>make-phong-material</strong> <em>[#:name "anonymous"] [#:blend-mode] [#:polygon-mode] [#:cull-face-mode] [#:depth-test] [#:stencil-test] [#:multisample? #f] [#:ambient-factor (vec3 1 1 1)] [#:diffuse-factor (vec3 1 1 1)] [#:specular-factor (vec3 1 1 1)] [#:shininess 32] [#:ambient-texture] [#:diffuse-texture] [#:specular-texture] [#:normal-texture]</em></dt>
<dd>
<p>Return a new Blinn-Phong material.
</p></dd></dl>
<dl>
<dt id="index-make_002dphong_002dproperties">Procedure: <strong>make-phong-properties</strong> <em>[#:ambient] [#:diffuse] [#:specular] [#:shininess]</em></dt>
<dd>
<p>Return a new Blinn-Phong properties object.
</p></dd></dl>
<dl>
<dt id="index-phong_002dproperties_003f">Procedure: <strong>phong-properties?</strong> <em>obj</em></dt>
<dd><p>Return <code>#t</code> if <var>obj</var> is a Blinn-Phong properties object.
</p></dd></dl>
<dl>
<dt id="index-phong_002dproperties_002dambient">Procedure: <strong>phong-properties-ambient</strong> <em>properties</em></dt>
<dd><p>Return the ambient factor of <var>properties</var>.
</p></dd></dl>
<dl>
<dt id="index-phong_002dproperties_002ddiffuse">Procedure: <strong>phong-properties-diffuse</strong> <em>properties</em></dt>
<dd><p>Return the diffuse factor of <var>properties</var>.
</p></dd></dl>
<dl>
<dt id="index-phong_002dproperties_002dspecular">Procedure: <strong>phong-properties-specular</strong> <em>properties</em></dt>
<dd><p>Return the specular factor of <var>properties</var>.
</p></dd></dl>
<dl>
<dt id="index-phong_002dproperties_002dshininess">Procedure: <strong>phong-properties-shininess</strong> <em>properties</em></dt>
<dd><p>Return the shininess factor of <var>properties</var>.
</p></dd></dl>
<span id="PBR-Materials"></span><h4 class="subsubsection">5.3.11.3 PBR Materials</h4>
<p>The <code>(chickadee graphics pbr)</code> module has the PBR lighting model:
</p>
<dl>
<dt id="index-make_002dpbr_002dmaterial">Procedure: <strong>make-pbr-material</strong> <em>[#:name "anonymous"] [#:blend-mode] [#:polygon-mode] [#:cull-face-mode] [#:depth-test] [#:stencil-test] [#:multisample? #f] [#:base-color-factor (vec3 1 1 1)] [#:base-color-texcoord 0] [#:metallic-factor 1.0] [#:roughness-factor 1.0] [#:metallic-roughness-texcoord 0] [#:normal-texcoord 0] [#:occlusion-texcoord 0] [#:emissive-factor (vec3 1 1 1)] [#:emissive-texcoord 0] [#:alpha-mode opaque] [#:alpha-cutoff 0.5] [#:base-color-texture] [#:metallic-roughness-texture] [#:normal-texture] [#:occlusion-texture] [#:emissive-texture]</em></dt>
<dd>
<p>Return a new PBR material.
</p></dd></dl>
<dl>
<dt id="index-make_002dpbr_002dproperties">Procedure: <strong>make-pbr-properties</strong> <em>[#:base-color-factor] [#:base-color-texcoord] [#:metallic-factor] [#:roughness-factor] [#:metallic-roughness-texcoord] [#:normal-texcoord] [#:occlusion-texcoord] [#:emissive-factor] [#:emissive-texcoord] [#:alpha-mode] [#:alpha-cutoff]</em></dt>
<dd>
<p>Return a new PBR properties object.
</p></dd></dl>
<dl>
<dt id="index-pbr_002dproperties_003f">Procedure: <strong>pbr-properties?</strong> <em>obj</em></dt>
<dd><p>Return <code>#t</code> if <var>obj</var> is a PBR properties object.
</p></dd></dl>
<dl>
<dt id="index-pbr_002dproperties_002dbase_002dcolor_002dfactor">Procedure: <strong>pbr-properties-base-color-factor</strong> <em>properties</em></dt>
<dd><p>Return the base color factor of <var>properties</var>.
</p></dd></dl>
<dl>
<dt id="index-pbr_002dproperties_002dbase_002dcolor_002dtexcoord">Procedure: <strong>pbr-properties-base-color-texcoord</strong> <em>properties</em></dt>
<dd><p>Return the base color texture coordinate attribute index of
<var>properties</var>.
</p></dd></dl>
<dl>
<dt id="index-pbr_002dproperties_002dmetallic_002dfactor">Procedure: <strong>pbr-properties-metallic-factor</strong> <em>properties</em></dt>
<dd><p>Return the metallic factor of <var>properties</var>.
</p></dd></dl>
<dl>
<dt id="index-pbr_002dproperties_002droughness">Procedure: <strong>pbr-properties-roughness</strong> <em>properties</em></dt>
<dd><p>Return the roughness factor of <var>properties</var>.
</p></dd></dl>
<dl>
<dt id="index-pbr_002dproperties_002dmetallic_002droughness_002dtexcoord">Procedure: <strong>pbr-properties-metallic-roughness-texcoord</strong> <em>properties</em></dt>
<dd><p>Return the metallic-roughness texture coordinate attribute index of
<var>properties</var>.
</p></dd></dl>
<dl>
<dt id="index-pbr_002dproperties_002dnormal_002dtexcoord">Procedure: <strong>pbr-properties-normal-texcoord</strong> <em>properties</em></dt>
<dd><p>Return the normal texture coordinate attribute index of
<var>properties</var>.
</p></dd></dl>
<dl>
<dt id="index-pbr_002dproperties_002docclusion_002dtexcoord">Procedure: <strong>pbr-properties-occlusion-texcoord</strong> <em>properties</em></dt>
<dd><p>Return the ambient occlusion texture coordinate attribute index of
<var>properties</var>.
</p></dd></dl>
<dl>
<dt id="index-pbr_002dproperties_002demissive_002dfactor">Procedure: <strong>pbr-properties-emissive-factor</strong> <em>properties</em></dt>
<dd><p>Return the emissive factor of <var>properties</var>.
</p></dd></dl>
<dl>
<dt id="index-pbr_002dproperties_002demissive_002dtexcoord">Procedure: <strong>pbr-properties-emissive-texcoord</strong> <em>properties</em></dt>
<dd><p>Return the emissive texture coordinate attribute index of
<var>properties</var>.
</p></dd></dl>
<dl>
<dt id="index-pbr_002dproperties_002dalpha_002dmode">Procedure: <strong>pbr-properties-alpha-mode</strong> <em>properties</em></dt>
<dd><p>Return the alpha mode of <var>properties</var>.
</p></dd></dl>
<dl>
<dt id="index-pbr_002dproperties_002dalpha_002dcutoff">Procedure: <strong>pbr-properties-alpha-cutoff</strong> <em>properties</em></dt>
<dd><p>Return the alpha cutoff threshold of <var>properties</var>.
</p></dd></dl>
<span id="Primitives-and-Meshes"></span><h4 class="subsubsection">5.3.11.4 Primitives and Meshes</h4>
<p>A mesh is a collection of “primitives,” so we should discuss those
next. A primitive contains vertex data and a material.
</p>
<dl>
<dt id="index-make_002dprimitive">Procedure: <strong>make-primitive</strong> <em>name vertex-array material</em></dt>
<dd><p>Return a new primitive named <var>name</var> that renders
<var>vertex-array</var> (see <a href="Buffers.html">Buffers</a>) using <var>material</var>.
</p></dd></dl>
<dl>
<dt id="index-primitive_003f">Procedure: <strong>primitive?</strong> <em>obj</em></dt>
<dd><p>Return <code>#t</code> if <var>obj</var> is a primitive.
</p></dd></dl>
<dl>
<dt id="index-primitive_002dname">Procedure: <strong>primitive-name</strong> <em>primitive</em></dt>
<dd><p>Return the name of <var>primitive</var>.
</p></dd></dl>
<dl>
<dt id="index-primitive_002dvertex_002darray">Procedure: <strong>primitive-vertex-array</strong> <em>primitive</em></dt>
<dd><p>Return the vertex array of <var>primitive</var>.
</p></dd></dl>
<dl>
<dt id="index-primitive_002dmaterial">Procedure: <strong>primitive-material</strong> <em>primitive</em></dt>
<dd><p>Return the material of <var>primitive</var>.
</p></dd></dl>
<p>Okay, now we can talk about meshes, which are just a glorified list of
primitive objects.
</p>
<dl>
<dt id="index-make_002dmesh">Procedure: <strong>make-mesh</strong> <em>name primitives</em></dt>
<dd><p>Return a new mesh named <var>name</var> that is composed of the list
<var>primitives</var>.
</p></dd></dl>
<dl>
<dt id="index-mesh_003f">Procedure: <strong>mesh?</strong> <em>obj</em></dt>
<dd><p>Return <code>#t</code> if <var>obj</var> is a mesh.
</p></dd></dl>
<dl>
<dt id="index-mesh_002dname">Procedure: <strong>mesh-name</strong> <em>mesh</em></dt>
<dd><p>Return the name of <var>mesh</var>.
</p></dd></dl>
<dl>
<dt id="index-mesh_002dprimitives">Procedure: <strong>mesh-primitives</strong> <em>mesh</em></dt>
<dd><p>Return the list of primitives for <var>mesh</var>.
</p></dd></dl>
<p>The mesh module also conveniently provides procedures to build several
basic 3D shapes.
</p>
<dl>
<dt id="index-make_002dplane">Procedure: <strong>make-plane</strong> <em>length width material</em></dt>
<dd><p>Return a new mesh that forms a flat plane on the XZ axis that is
<var>width</var> units long along the X axis and <var>length</var> units long
along the Z axis.
</p></dd></dl>
<dl>
<dt id="index-make_002dtesselated_002dplane">Procedure: <strong>make-tesselated-plane</strong> <em>length width resolution material</em></dt>
<dd><p>Return a new mesh that forms a tesselated plane on the XZ axis that is
<var>width</var> units long along the X axis and <var>length</var> units long
along the Z axis.
</p>
<p>A regular plane is a single rectangle, but a tesselated plane is
subdivided into many smaller rectangles by <var>resolution</var>. This
allows for transforming the vertices in a shader to achieve effects
such as waves in water or mountainous terrain.
</p></dd></dl>
<dl>
<dt id="index-make_002dcube">Procedure: <strong>make-cube</strong> <em>size material</em></dt>
<dd><p>Return a new mesh that forms a cube that is <var>size</var> units big.
</p></dd></dl>
<dl>
<dt id="index-make_002dsphere">Procedure: <strong>make-sphere</strong> <em>radius material [#:quality 2]</em></dt>
<dd><p>Return a new mesh that forms a sphere that has a radius of
<var>radius</var> units. Since 3D models are composed of triangles, the
quality of a sphere is entirely dependent upon how many triangles are
used to appromixate the shape. The higher the value of <var>quality</var>,
the better the appromixation, but the more time it will take to
generate and the more expensive it will be to draw. The number of
triangles in the resulting sphere increases exponentially with each
increment to <var>quality</var>.
</p></dd></dl>
<hr />
<div class="header">
<p>
Next: <a href="Buffers.html" accesskey="n" rel="next">Buffers</a>, Previous: <a href="Skyboxes.html" accesskey="p" rel="prev">Skyboxes</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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