Model Loader ( Assimp )

17/2/2013

Okay so I've started the initial workings of the model loader and managed to import a simple cube model using Assimp. This is all put into Mesh and Submesh classes which is then used for the render code. You can see the cube in the image on the left.

There are still many mesh features that need implementing. Currently only the vertices and the face indices have been used to create this cube and the colour is set as a uniform variable in the shader. The next step is to gradually add more information from the mesh files such as: normals, textures, colour( ambient, diffuse and specular ) and eventually animation information. Hopefully it won't be long before I have something that I could potentially create a game with. I already have a simple Camera class and a window class for initialising the OpenGL and handling the render loop.

The next thing I will be focusing on is adding the colours and normals from a mesh file so that it can be used for lighting calculations. I also need to wrap up how the mesh and submesh classes create and communicate with the OpenGL data, i.e. the VBO's EBO's and the VAO. This will take some great deal of thought.

Till next time :)

6 Comments

Paul

11/5/2013 03:42:49 am

A tutorial would be nice, because Assimp and every other tutorial I've seen so far don't explain fully how to even get that far

Jordan Bonser

11/5/2013 03:49:34 am

Yeah I know what you mean the tutorials out there aren't particularly in depth. One good one I found was at ogldev.atspace.co.uk . Tutorial 22 explains most of the assimp importer stuff. The only thing it doesn't show well, is how to take the imported data and apply it to your own classes and data types.

ockert link

3/7/2013 09:52:21 am

Do you know how to use that bool aiMesh::HasVertexColors (unsigned int pIndex) const [inline] chappy to get colours from thhe modeller into your buffer?

4/7/2013 03:57:24 am

Hey this is the way I've implemented it:
for( unsigned int i = 0; i < theMesh->mNumVertices; i++ )
{

//Get all the vertex Colours.. Can be up to 8 ( not likely tho )
unsigned int NumColours = theMesh->GetNumColorChannels();

for( unsigned int j = 0; j < NumColours; j++ )
{
if( theMesh->HasVertexColors(j) )
{
float red = theMesh->mColors[j][i].r ;
float green = theMesh->mColors[j][i].b ;
float blue = theMesh->mColors[j][i].g ;
}
}
}

2/12/2013 11:22:16 am

Cool thanks. In doing so I get weird values for the red green an blue channels, Running
.
.
.

printf("aiScene->mMeshes[%i]->mColors[%i][%i]: [%f, %f, %f, %f]\n",
i,
j,
k,
(float)aiSceneP->mMeshes[i]->mColors[j][k][0],
(float)aiSceneP->mMeshes[i]->mColors[j][k][1],
(float)aiSceneP->mMeshes[i]->mColors[j][k][2],,
(float)aiSceneP->mMeshes[i]->mColors[j][k][3]);//.a);
}
.
.
.

...I find values like

aiScene->mMeshes[0]->mColors[0][3]: [-1.000000, -109.000000, -5.000000, -1.000000]
aiScene->mMeshes[0]->mColors[0][4]: [-96.000000, 30.000000, -1.000000, -1.000000]
aiScene->mMeshes[0]->mColors[0][5]: [-4.000000, -5.000000, -1.000000, -1.000000]

I've looked everywhere, I'm importing Blender 2.62 files

Have you come across similar problems?

9/12/2013 09:33:51 am

Hmm that does seem quite strange, I've never tried importing blender files. The only other thing I could suggest is maybe importing the file into blender and see if the values are the same.

I know blender does have a lot of options when exporting files so maybe there is some setting that was not applied when exporting the model.

Sorry I couldn't be more helpful

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Model Loader ( Assimp )

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