I have just read this tutorial about how to load a 3D model file. Its render routine uses a recursive_render function to scan all nodes.

My question:

  1. What does a aiNode struct store?
  2. What the difference between this method and above method:

    for (int i=0; i < scene->mNumMesh; ++i) {
       draw scene->mMeshes[i];

1) The aiNode struct is defined in the Assimp library. Here you can find it its definition on the official documentation:

Public Attributes
aiNode **       mChildren       // The child nodes of this node.
unsigned int *  mMeshes         // The meshes of this node.
aiString        mName           // The name of the node.
unsigned int    mNumChildren    // The number of child nodes of this node.
unsigned int    mNumMeshes      // The number of meshes of this node.
aiNode *        mParent         // Parent node.
aiMatrix4x4     mTransformation // The transformation relative to the node's parent. 

2) I don't know what is the difference between "your method" and recursive_render, but looks like you are missing a lot of information (childs, etc). I'd have a closer look to recursive_render

  • \$\begingroup\$ thanks for reply, that is what i do not understands, why they are divided model into more "nodes" but not only meshes? \$\endgroup\$ – Bình Nguyên Jun 20 '12 at 15:29
  • \$\begingroup\$ For a definition of "node", I recommend that you read the section about "The Node Hierarchy" from assimp.sourceforge.net/lib_html/data.html. "A node can potentially refer to single or multiple meshes. The meshes are not stored inside the node, but instead in an array of aiMesh inside the aiScene. A node only refers to them by their array index. This also means that multiple nodes can refer to the same mesh, which provides a simple form of instancing." \$\endgroup\$ – Dan Jun 20 '12 at 15:45

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