by JackDesBwa 2021-06-07 09:59
This is a drawing test I made with blender using its grease pencil tool.
I first prepared a simple and very rough 3D model made of an ellipsoid for the body, two spheres for the eyes and four planes for the fins. Then I added a GreasePencil object and configured the pen to write onto the surface of the objects as seen from the current view.
At this point, I could move the view around the model to find the most convenient place to draw, and the digital ink was placed directly in 3D. Using a stereoscopic camera, it was easy to preview the result and adjust the lines whenever needed.
The tricky part was the body, because its lines do not have a true meaning in full 3D, only from the viewpoint of the camera. So I placed myself in the camera's view and drew some lines that somewhat made sense. The positions of the fins had to be adjusted to match these lines, which was fortunately easy with blender.
The next step was to hide the helping model. Unfortunately, this means that we saw through the body and some lines behind it appeared, which was not interesting. I added an ellipsoid adjusted to the lines of the body from the viewpoint of the camera with a texture made with a "holdout" shader. This make an opaque shape that is rendered in transparent color in the final image.
For the composition, I added an object in the top-left corner. I first drew it in a plane parallel to the camera, and used the sculpt tools to move the points in 3D space.
The final render was just the lines over a transparent background. I composited it over a blue background in Gimp afterwards. I also made a drawing animation of it: https://youtu.be/lkmQgE1C9jI
-- 2021-06-06, blender