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POGeneralized (non-slicing) pointer to templated tree nodes? (C++)
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  1. POGeneralized (non-slicing) pointer to templated tree nodes? (C++)
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    copied!<p>I'm working on an octree implementation where the tree nodes are templated with their dimensional length (as a power of 2):</p> <pre><code>template&lt;long N&gt; struct node_t { enum { DIM = 1 &lt;&lt; N }; node_t&lt;N+1&gt; * parent; node_t&lt;N-1&gt; * children[8]; long count; } </code></pre> <p>And specialized for N = 0 (leaves) to point to data.</p> <pre><code>struct node_t&lt;0&gt; { enum { DIM = 1 }; node_t&lt;1&gt; * parent; data_t data; long count; } </code></pre> <p>(<strong>Aside:</strong> I suppose I probably also need a specialization for N_MAX that excludes a parent pointer, or else C++ will generate types of increasing N ad finitum? But that's not really relevant to my question.)</p> <p>I'd like to create a function that steps along a ray in the 3D space that my octree occupies, so ostensibly I could just keep a pointer to the root node (which has a known type) and traverse the octree from the root at every step. However, I would prefer a more 'local' option, in which I can keep track of the current node so that I can start lower in the tree when possible and thus avoid unnecessarily traversing the upper nodes of the octree.</p> <p>But I don't know what that type pointer could be (or any other way of implementing this) so that I don't experience slicing.</p> <p>I'm not tied down to templates, as the dimension can simply be implemented as a <code>long const</code>. But then I don't know how to make it so that the leaves have a different child type than inodes.</p> <p>Thanks for your help!</p> <h2>Update</h2> <p>The reason I'd like to do it this way rather than something similar to <a href="https://stackoverflow.com/questions/6281415/octree-raycasting-raytracing-best-ray-leaf-intersection-without-recursion?rq=1">this</a> is because of the <code>count</code> variable in each node: if the count is 0, I'd like to jump through the whole cube, rather wasting time going through leaves that I know to be empty. (This is for a raytracing voxel engine.)</p>
 

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