"""
Constructive CAD modeling
=========================

Hand-authoring control points (as in :doc:`/tutorials/01_first_bspline`) does not
scale. :mod:`pantr.cad` builds B-spline geometry the way a CAD kernel does: primitives
(lines, circles, disks, cylinders) combined by operations (extrusion, revolution, ruled
surfaces, sweeps, Coons patches) and assembled with ``join``. Every result is an
ordinary :class:`~pantr.bspline.Bspline`, so it supports evaluation, derivatives, and
the knot operations from the previous tutorial.

This tutorial builds a few shapes and lays them out in one scene; the
:doc:`/guide/cad` guide is the complete reference for the module.
"""

from pantr import viz
from pantr.cad import (
    create_circle,
    create_cylinder,
    create_extrusion,
    create_line,
    create_revolution,
    create_ruled,
)
from pantr.transform import AffineTransform

# %%
# Primitives
# ----------
# A cylinder is a rational surface; rendering uses exact Bézier cells.
cylinder = create_cylinder(radius=0.5, height=1.5)
viz.plot(cylinder, color="lightsteelblue", show_knot_lines=True)

# %%
# Extrusion: sweep a profile along a vector
# -----------------------------------------
# Extruding a circle along +z produces a tube wall.
tube = create_extrusion(create_circle(radius=0.5), displacement=[0.0, 0.0, 1.2])
viz.plot(tube, color="wheat", show_knot_lines=True)

# %%
# Revolution: spin a profile about an axis
# -----------------------------------------
# Revolving a slanted line about the z-axis gives a cone-like surface of revolution.
profile = create_line(p0=[0.2, 0.0, 0.0], p1=[0.6, 0.0, 1.0])
surface_of_revolution = create_revolution(profile, point=[0.0, 0.0, 0.0], axis=2)
viz.plot(surface_of_revolution, color="thistle", show_knot_lines=True)

# %%
# Ruled surface between two curves
# --------------------------------
# A ruled surface linearly interpolates between two curves -- here two circles of
# different radius at different heights, giving a conical frustum.
bottom = create_circle(radius=0.7, center=[0.0, 0.0, 0.0])
top = create_circle(radius=0.3, center=[0.0, 0.0, 1.0])
frustum = create_ruled(bottom, top)
viz.plot(frustum, color="lightgreen", show_knot_lines=True)

# %%
# An assembled scene
# ------------------
# Lay the shapes side by side by translating each (transforms are covered in
# :doc:`/tutorials/10_transforms`) and adding them to one :class:`~pantr.viz.Scene`.
scene = viz.Scene()
for i, geom in enumerate([cylinder, tube, surface_of_revolution, frustum]):
    placed = geom.transform(AffineTransform.translation([2.0 * i, 0.0, 0.0]))
    scene.add(placed, show_knot_lines=True)
scene.show()