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POCocoa - OpenGL ES - Wrapping my head around C-Arrays
 

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  1. POCocoa - OpenGL ES - Wrapping my head around C-Arrays
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    <p>This is more of a general theory question that I just cant seem to wrap my head around, so Ill explain what Im trying to do.</p> <p>Im writing a 3D Game Engine with Cocoa and OpenGL ES. Im trying to determine the best way to store my vertex data for my 3d models (each vertex has an x, y, and z position).</p> <p>Previously, I was storing each vertex as an individual custom object (<code>AEVertex</code>), this object had an x, y, and z instance variable. The issue is I am using the command <code>glDrawArrays()</code>, which takes the address of a C-Array as it's first param. This C-Array is supposed to be a one-dimensional array storing all of the vert positions in succesion (vert 1's x position, vert 1's y position, vert 1's z position, vert 2's x position, vert 2's y position, vert 2's z position, etc, etc).</p> <p>The issue I faced was that I had to gather all of the vertexdata for a given model from each individual vertex object and create a C-Array big enough to store all of these verts / fill the C-Array with the vert data, and then pass in this array. This is obviously going to slow things down a lot, as I am essentially allocating memory for every model twice.</p> <p>So what I would LIKE to do is simply have a class AEMesh, that has a C-Array instance variable that stores all of the vertexdata for the given AEMesh object. My issue with this is that as far as I know its only possible to declare C-Array instance variables of a fixed size, however a) all of my models will have different numbers of vertices and b) I wont know how many verts each model has until reading in the model data at runtime.</p> <p>So, my questions:</p> <ol> <li><p>Is there some way to create a mutable, dynamic C-Array as an instance variable for an object? Thus allowing me to add new array indices for every vertex read in from a given AEMesh's model file?</p></li> <li><p>If not, Im wondering if I can create the vertexdata C-Array outside of the AEMesh's initialization, and simply have a pointer instance variable pointing to nil when an AEMesh is instantiated, and repointed to the created C-Array after the C-Array is declared.</p></li> </ol>
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