As per my understanding, you have the X, Y, Z data for the grid in a .dat file that you want to convert to an STL file and you are using this FileExchange submission to do the same,
If this is correct, then you should first read through the CONVERT_voxels_to_stl_example.m script to see how the function is being called and how a .stl file is generated.
The example uses a .mat file but you can use the same for .dat files, you'll just have to load it in the same way,
load(<Filename.dat>)
But if you get difficulties with this load call, then you can refer to the discussion on the following MATLAB Answer, https://www.mathworks.com/matlabcentral/answers/79885-how-to-read-tabular-data-from-dat-files-into-matlab
And then call the, CONVERT_voxels_to_stl() method.
This is what the inputs and outputs mean as per the FileExchange documentation,
Converts the voxelised object contained within the 3D logical array <gridINPUT> into an STL surface mesh, which is saved to the ascii file <STLin>. The x,y,z axes for <gridINPUT> are defined by <gridX>, <gridY> and <gridZ>. The (faces,vertices) data are optional outputs.
So you must write a new script (.m file) that first loads the .dat file which will give you the x, y and z data and then call the convert() function. And you don't have to edit any of the FileExchange files, they are intended to be used out of the box.
