Creating a parent-child structure with assimp | Code Society | Page 1

knotty peak Jan 21, 2023, 3:56 PM

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I'm having a bit of a hard time constructing a tree like structure ussing assimp and openGL
This is called recursively and it should give me this:
parent Model -> child Model (this one should contain a Mesh)

but at the end of the process the parent model contains a child model but the child model in question does not have a mesh
(I checked and the function addMesh is called)
Thanks,

void Model::parseNodes(aiNode* node, const aiScene* scene, Model& parent) {
    
    Model model;
    
    for (size_t i = 0; i < node->mNumMeshes; i++)
    {
        ...
        Mesh mesh = createMesh(scene->mMeshes[currentMesh], scene);
        model.addMesh(mesh);
    }
    model.m_localTransform = node->mTransformation * parent.m_localTransform;
    parent.addChild(model);
    for (size_t i = 0; i < node->mNumChildren; i++)
    {
      parseNodes(node->mChildren[i], scene, model);
    }
}

the signature of the important functions
void addChild(Model& child);
void addMesh(Mesh mesh);

zealous barn Jan 21, 2023, 4:05 PM

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None of them have mesh or only the last child?

knotty peak Jan 21, 2023, 4:06 PM

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none of them, I should only be the last child who have a mesh tho

zealous barn Jan 21, 2023, 4:08 PM

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did you try putting a breakpoint inside the addmesh function and using the debugger?

knotty peak Jan 21, 2023, 4:10 PM

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yes, it goes into addmesh()

zealous barn Jan 21, 2023, 4:10 PM

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and was the mesh added after the function?

knotty peak Jan 21, 2023, 4:11 PM

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yes which is why I found it strange

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I think I found a solution tho, I might have been a reference problem ?
I returned the reference to the added object in addChild() and passed it as the argument for
parseNodes()

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don't know if this is good tho

zealous barn Jan 21, 2023, 4:21 PM

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does m_children contains pointers or only a copy of child?

knotty peak Jan 21, 2023, 4:29 PM

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copy of child

zealous barn Jan 21, 2023, 4:33 PM

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when you used the debugger you saw the last model being added to the node ? and the mesh was there ? then at the first end of the function the mesh just disappeared? @knotty peak

knotty peak Jan 21, 2023, 4:36 PM

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if by first end of the function you mean first call then not really because the mesh is only in the second call of the function (so in the second child)
I indeed saw the mesh was added to the model
but when I call the draw function (which is supposed to call the mesh of each child of my Model)
it does nothing (because it does not have a mesh)

zealous barn Jan 21, 2023, 4:37 PM

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but do you see the mesh inside the variable in the debugger?

knotty peak Jan 21, 2023, 4:37 PM

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It said m_meshes[1] so yes

zealous barn Jan 21, 2023, 4:38 PM

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does your node have a destructor which free the mesh?

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I mean model*

knotty peak Jan 21, 2023, 4:39 PM

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no it does not

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I didn't create one because I (at least I don't think) don't have dynamically allocated objects

zealous barn Jan 21, 2023, 4:44 PM

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knotty peak It said m_meshes[1] so yes

where it says m_meshes[1], do you see the mesh data structure as well, also you said draw does nothing , are you 100% sure its because of the mesh ?

knotty peak Jan 21, 2023, 4:47 PM

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I must say I didn't check
I said it draws nothing but it's more like it does not even enter the loop
for(Mesh mesh : m_meshes)

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I don't have access to my pc anymore to check for the data structure tho, sorry

#Creating a parent-child structure with assimp