I have a model of a flag to which I would like to add the texture of a flag. The model of the flag is a mesh, and the curves it is made of are rather complex. How would I add a texture to this, so that the texture flows along the folds of the flag?
Did you you some type of physics to generate the shape from a plane to the freeform result?
If not, no mapping type will result in the ability to apply a rectangular image.
If the form was created arbitrarily, there is no way it will result in a rectangular map, and you won’t be able to create the map manually due to the complexity after it is unfolded.
If you don’t know how the form was created you might use Squish to get an approximate 2D shape but my intuition tells me its not going to be a perfect rectangle.
If you are not forced to use this specific form, you could look at this video for Blender.
Potentially you can create a new form that would unwrap approximately to a rectangle.