de.javagl.obj.ObjData Java Examples

/**
 * Create a byte buffer containing the data of the indices for the
 * given OBJ. The face vertex indices of the given OBJ will be 
 * extracted (assuming that it contains only triangles), converted
 * to the given indices component type (which is a GL constant like
 * GL_SHORT), and a byte buffer containing these indices will be returned.
 * 
 * @param obj The OBJ
 * @param indicesComponentType The indices component type
 * @return The byte buffer
 */
private static ByteBuffer createIndicesByteBuffer(
    ReadableObj obj, int indicesComponentType)
{
    int numVerticesPerFace = 3;
    IntBuffer objIndices = 
        ObjData.getFaceVertexIndices(obj, numVerticesPerFace);
    int indicesComponentSize =
        Accessors.getNumBytesForAccessorComponentType(
            indicesComponentType);
    ByteBuffer indicesByteBuffer = 
        IntBuffers.convertToByteBuffer(objIndices, indicesComponentSize);
    return indicesByteBuffer;
}
 

/**
 * Create a byte buffer containing the data of the indices for the
 * given OBJ. The face vertex indices of the given OBJ will be 
 * extracted (assuming that it contains only triangles), converted
 * to the given indices component type (which is a GL constant like
 * GL_SHORT), and a byte buffer containing these indices will be returned.
 * 
 * @param obj The OBJ
 * @param indicesComponentType The indices component type
 * @return The byte buffer
 */
private static ByteBuffer createIndicesByteBuffer(
    ReadableObj obj, int indicesComponentType)
{
    int numVerticesPerFace = 3;
    IntBuffer objIndices = 
        ObjData.getFaceVertexIndices(obj, numVerticesPerFace);
    int indicesComponentSize =
        Accessors.getNumBytesForAccessorComponentType(
            indicesComponentType);
    ByteBuffer indicesByteBuffer = 
        IntBuffers.convertToByteBuffer(objIndices, indicesComponentSize);
    return indicesByteBuffer;
}
 

/**
 * Create the {@link MeshPrimitive} from the given OBJ data.
 * 
 * @param part The OBJ
 * @param partName A name that will be used as a basis to create the IDs of 
 * the {@link BufferView} and {@link Accessor} instances
 * @return The {@link MeshPrimitive}
 */
private MeshPrimitive createMeshPrimitive(ReadableObj part, String partName)
{
    MeshPrimitive meshPrimitive = 
        new MeshPrimitive();
    meshPrimitive.setMode(GltfConstants.GL_TRIANGLES);

    // Add the indices data from the OBJ to the buffer structure
    String indicesAccessorId = partName + "_indices"; 
    bufferStructureBuilder.createAccessorModel(
        indicesAccessorId, indicesComponentType, "SCALAR", 
        createIndicesByteBuffer(part, indicesComponentType));
    meshPrimitive.setIndices(indicesAccessorId);
    
    bufferStructureBuilder.createArrayElementBufferViewModel(
        partName + "_indices_bufferView");
    
    // Add the vertices (positions) from the OBJ to the buffer structure
    String positionsAccessorId = partName + "_positions";
    FloatBuffer objVertices = ObjData.getVertices(part);
    bufferStructureBuilder.createAccessorModel(
        positionsAccessorId, GltfConstants.GL_FLOAT, "VEC3", 
        Buffers.createByteBufferFrom(objVertices));
    meshPrimitive.addAttributes("POSITION", positionsAccessorId);

    // Add the texture coordinates from the OBJ to the buffer structure
    boolean flipY = true;
    FloatBuffer objTexCoords = ObjData.getTexCoords(part, 2, flipY);
    if (objTexCoords.capacity() > 0)
    {
        String texCoordsAccessorId = partName + "_texcoords0";
        bufferStructureBuilder.createAccessorModel(
            texCoordsAccessorId, GltfConstants.GL_FLOAT, "VEC2", 
            Buffers.createByteBufferFrom(objTexCoords));
        meshPrimitive.addAttributes("TEXCOORD_0", texCoordsAccessorId);
    }
    
    // Add the normals from the OBJ to the buffer structure
    FloatBuffer objNormals = ObjData.getNormals(part);
    if (objNormals.capacity() > 0)
    {
        ObjNormals.normalize(objNormals);
        String normalsAccessorId = partName + "_normals";
        bufferStructureBuilder.createAccessorModel(
            normalsAccessorId, GltfConstants.GL_FLOAT, "VEC3", 
            Buffers.createByteBufferFrom(objNormals));
        meshPrimitive.addAttributes("NORMAL", normalsAccessorId);
    }

    bufferStructureBuilder.createArrayBufferViewModel(
        partName + "_attributes_bufferView");
    
    return meshPrimitive;
}
 

/**
 * Create the {@link MeshPrimitive} from the given OBJ data.
 * 
 * @param part The OBJ
 * @param partName A name that will be used as a basis to create the IDs of 
 * the {@link BufferView} and {@link Accessor} instances
 * @return The {@link MeshPrimitive}
 */
private MeshPrimitive createMeshPrimitive(ReadableObj part, String partName)
{
    MeshPrimitive meshPrimitive = 
        new MeshPrimitive();
    meshPrimitive.setMode(GltfConstants.GL_TRIANGLES);

    // Add the indices data from the OBJ to the buffer structure
    int indicesAccessorIndex = 
        bufferStructureBuilder.getNumAccessorModels();
    bufferStructureBuilder.createAccessorModel(
        "indicesAccessor_" + indicesAccessorIndex,
        indicesComponentType, "SCALAR", 
        createIndicesByteBuffer(part, indicesComponentType));
    meshPrimitive.setIndices(indicesAccessorIndex);
    
    bufferStructureBuilder.createArrayElementBufferViewModel(
        partName + "_indices_bufferView");
    
    // Add the vertices (positions) from the OBJ to the buffer structure
    int positionsAccessorIndex = 
        bufferStructureBuilder.getNumAccessorModels();
    FloatBuffer objVertices = ObjData.getVertices(part);
    bufferStructureBuilder.createAccessorModel(
        "positionsAccessor_" + positionsAccessorIndex,
        GltfConstants.GL_FLOAT, "VEC3", 
        Buffers.createByteBufferFrom(objVertices));
    meshPrimitive.addAttributes("POSITION", positionsAccessorIndex);

    // Add the texture coordinates from the OBJ to the buffer structure
    boolean flipY = true;
    FloatBuffer objTexCoords = ObjData.getTexCoords(part, 2, flipY);
    if (objTexCoords.capacity() > 0)
    {
        int texCoordsAccessorIndex = 
            bufferStructureBuilder.getNumAccessorModels();
        bufferStructureBuilder.createAccessorModel(
            "texCoordsAccessor_" + texCoordsAccessorIndex, 
            GltfConstants.GL_FLOAT, "VEC2", 
            Buffers.createByteBufferFrom(objTexCoords));
        meshPrimitive.addAttributes("TEXCOORD_0", texCoordsAccessorIndex);
    }
    
    // Add the normals from the OBJ to the buffer structure
    FloatBuffer objNormals = ObjData.getNormals(part);
    if (objNormals.capacity() > 0)
    {
        ObjNormals.normalize(objNormals);
        int normalsAccessorIndex = 
            bufferStructureBuilder.getNumAccessorModels();
        bufferStructureBuilder.createAccessorModel(
            "normalsAccessor_" + normalsAccessorIndex, 
            GltfConstants.GL_FLOAT, "VEC3", 
            Buffers.createByteBufferFrom(objNormals));
        meshPrimitive.addAttributes("NORMAL", normalsAccessorIndex);
    }

    bufferStructureBuilder.createArrayBufferViewModel(
        partName + "_attributes_bufferView");
    
    return meshPrimitive;
}