GreasePencil

resources which cover this:

• query-grease-pencil-strokes-from-python
• convert-curves-to-grease-pencil

drawing trigonometry using Grease Pencil.

import math
import bpy


def get_layer(gdata_owner, layer_name):

    grease_data = bpy.data.grease_pencil
    if gdata_owner not in grease_data:
        gp = grease_data.new(gdata_owner)
    else:
        gp = grease_data[gdata_owner]

    # get grease pencil layer
    if not (layer_name in gp.layers):
        layer = gp.layers.new(layer_name)
        layer.frames.new(1)
        layer.line_width = 1
    else:
        layer = gp.layers[layer_name]
        layer.frames[0].clear()

    return layer


def generate_gp3d_stroke(layer):
    layer.show_points = True
    layer.color = (0.2, 0.90, .2)
    s = layer.frames[0].strokes.new()
    s.draw_mode = '3DSPACE'  # or '2DSPACE'

    chain = []
    num_verts = 10
    r = 2.2
    gamma = 2 * math.pi / num_verts
    for i in range(num_verts+1):
        theta = gamma * i
        world_point = (math.sin(theta) * r, math.cos(theta) * r, 1.2)
        chain.append(world_point)

    s.points.add(len(chain))
    for idx, p in enumerate(chain):
        s.points[idx].co = p
        # s.points[idx].pressure = 1.0   # if 2DSPACE


class TrigGenerator(bpy.types.Operator):

    bl_idname = 'mesh.trig_generator'
    bl_label = 'generated trig with gpencil'
    bl_options = {'REGISTER', 'UNDO'}

    def execute(self, context):
        obj = bpy.context.object
        data_name = 'stack_data'
        layer_name = "stack layer"
        layer = get_layer(data_name, layer_name)
        generate_gp3d_stroke(layer)
        context.scene.grease_pencil = bpy.data.grease_pencil[data_name]
        return {'FINISHED'}


def register():
    bpy.utils.register_class(TrigGenerator)


def unregister():
    bpy.utils.unregister_class(TrigGenerator)


if __name__ == '__main__':
    register()

Font to grease pencil.

Font must be converted to Mesh first. Ideally we'd use Ngons to keep the number of strokes down, but GP fills polygons using the Fan method and this doesn't treat irregular concave polygons very well. A way to get the font to display in a usable way is to triangulate or Quad the mesh first. .. then run the script. (or include this as an automated step in the script)

import bpy

def get_layer(gdata_owner, layer_name):

    grease_data = bpy.data.grease_pencil
    if gdata_owner not in grease_data:
        gp = grease_data.new(gdata_owner)
    else:
        gp = grease_data[gdata_owner]

    # get grease pencil layer
    if not (layer_name in gp.layers):
        layer = gp.layers.new(layer_name)
        layer.frames.new(1)
        layer.line_width = 1
    else:
        layer = gp.layers[layer_name]
        layer.frames[0].clear()

    return layer

def generate_gp3d_stroke(obj, layer):
    layer.show_points = True
    layer.color = (0.2, 0.90, .2)

    verts = obj.data.vertices
    for f in obj.data.polygons:

        s = layer.frames[0].strokes.new()
        s.draw_mode = '3DSPACE'  # or '2DSPACE'
        s.points.add(len(f.vertices))
        for i, v in enumerate(f.vertices):
            p = s.points[i]
            p.co = verts[v].co
            p.pressure = 1.0

def main():
    obj = bpy.context.active_object
    data_name, layer_name = 'stack_data', "stack layer"
    layer = get_layer(data_name, layer_name)
    generate_gp3d_stroke(obj, layer)
    bpy.context.scene.grease_pencil = bpy.data.grease_pencil[data_name]

main()