<p>You can only update content of buffers, you cannot resize buffers (this is very costly, basically equivalent to creating new geometry). </p>
<p>You can emulate resizing by pre-allocating larger buffer and then keeping unneeded vertices collapsed / hidden.</p>
<p>Set flags only for attributes that you need to update, updates are costly. Once buffers change, these flags reset automatically back to <code>false</code>. You need to keep setting them to <code>true</code> if you wanna keep updating buffers.</p>
<p>In versions prior to <ahref="https://github.com/mrdoob/three.js/releases/tag/r66">r66</a> meshes additionally need the <code>dynamic</code> flag enabled (to keep internal typed arrays).</p>
<p>All uniforms values can be changed freely (e.g. colors, textures, opacity, etc), values are sent to shader every frame.</p>
<p>Also GL state related parameters can change any time (depthTest, blending, polygonOffset, etc).</p>
<p>Flat / smooth shading is baked into normals. You need to reset normals buffer (see above).</p>
<p>Properties that can't be easily changed in runtime (once material is rendered at least once):</p>
<ul>
<li>numbers and types of uniforms</li>
<li>numbers and types of lights</li>
<li>presence or not of
<ul>
<li>texture</li>
<li>fog</li>
<li>vertex colors</li>
<li>skinning</li>
<li>morphing</li>
<li>shadow map</li>
<li>alpha test</li>
</ul>
</li>
</ul>
<p>Changes in these require building of new shader program. You'll need to set <code>material.needsUpdate</code> flag to <code>true</code>. </p>
<p>Bear in mind this might be quite slow and induce jerkiness in framerate (especially on Windows, as shader compilation is slower in DirectX than OpenGL).</p>
<p>For smoother experience you can emulate changes in these features to some degree by having "dummy" values like zero intensity lights, white textures, or zero density fog.</p>
<p>You can change freely material used for geometry chunk, you cannot change how object is divided into chunks (according to face materials). </p>
<p>If you need to have different configurations of materials during runtime, if number of materials / chunks is small, you could pre-divide object beforehand (e.g. hair / face / body / upper clothes / trousers for human, front / sides / top / glass / tire / interior for car). </p>
<p>If number is large (e.g. each face could be potentially different), consider different solution, using attributes / textures to drive different per-face look.</p>
