Blender Vector Field

This script takes in a json file of the format shown in sample-vector-field.json, an object line arrow.obj, and the name of the collection you want to add the vector to. It then creates a bunch of copies of arrow.obj and puts them in the collection with the orientations specified in the json file along with the proper scaling and coloring.

How to Use

There are only five steps.

1. Create a model for the arrow or use arrow.obj.
2. Put generate_vector_field.py in your blender project.
3. Either create a material known as arrow-material or run the script once and edit the result.
4. Create a .json file in the format specified below. You can use sample-vector-field.json as an example.
5. Create a new python file for every vector field you want to generate.
6. Each python file should create a Vector_Field object and then call generate_vector_field.

You can see the exact syntax for creating a Vector_Field object and for calling the generate_vector_field function at the bottom of generate_vector_field.py.

The Arrows

The arrows can be any .obj you like, but you need to make sure to do two things:

1. Export them so that the positive z direction is up and the positive x direction is forward.
2. Do not export them with any materials or you're never going to have to search through thousands of unused materials to find the right one.

Notes

First, you can and probably should use another programming language to generate the .json file for the vector fields. I have several of these scrips in demo. Second, it is important that you give unique names for the collections you want to add the arrows to or else you're going to end up adding vectors to the wrong collections, which usually means you're going to be adding them to either the wrong scene or no scene at all. Lastly, you might need to mess around with the arrow-material to get it to properly color all the arrows. Something like this should suffice for most needs.

json Format

Currently, there are five main things in the json file.

• max_length: The maximum possible length of a vector.
• min_length: Vectors with a length below this are not put into the file.
• avg_length: Vectors with this length are exactly half of max_length.
• colorscheme: A list of colors and values to map to the color. If the color value of a vector is given by the value col, then the color in the rendered vector field will be interpolated between the two colors with the closest values. If col is less than the minimum color value, then the vector will have the color with the minimum value. Likewise, if col is greater than the maximum color value, then the vector will have the color with the maximum value.
  • value_to_map_to_this_color: Where we put colors on the real line.
  • color_space: Specified in the generate_vector_field.py function. Basically, it corresponds to a color space in python's colormath library.
  • format: hex if you use the format #DC143C and num if you use the format [ 1.0, 0.5, 1.0 ].
  • color: A standard way of specifying the color.
  • kwargs: Use this to override everything else, such as in the case for a spectral color (see the colormath library for more documentation).
• vectors: A list of vectors.
  • pos: Where you want the vector to be.
  • vec: The vector you want to place.
  • rot: (Optional) The rotation around the z-axis before you rotate to the proper vector.
  • col: (Optional) By default, vectors are colored by their length. If you want to override it, provide this option.

Improvements

I'm probably going to add more to this later, specifically for animation, but not right now. If someone were to pay me, I might be more motivated to move forward with this script. Otherwise, I'm only going to update the script when I need to update it.

Contributions

You can also contribute through the standard github way. I will accept any contribution that adds a new feature that adds a new feature or fixes a bug as long as doing so does not lead to unnecessary entanglement with other code bases or systems. For example, I will not accept a pull request that generates the json inside the script or tries to get around the json file in any way. Adding such code is like tying your shoes together so that you only have to tie them once. On the other hand, adding a new feature like animation to the json file is something I'd probably accept, especially if it can be done without breaking compatibility with older versions.