chapter06_render_phong_sphere.py

from core import (Canvas, Ray, color, hit, lighting, negate, normalize, point,
                  scaling, subtract)
from lights import PointLight
from shapes import Material, Sphere


def main():
    canvas_pixels = 500
    canvas = Canvas(canvas_pixels, canvas_pixels)
    shape = Sphere()

    # assign material
    shape.material = Material()
    shape.material.color = color(1, 0.2, 1)

    light_position = point(-10, 10, -10)
    light_color = color(1, 1, 1)
    light = PointLight(light_position, light_color)

    ray_origin = point(0, 0, -5)
    wall_z = 10
    wall_size = 7.0

    pixel_size = wall_size / canvas_pixels
    half = wall_size / 2

    for y in range(canvas_pixels):
        world_y = half - pixel_size * y

        for x in range(canvas_pixels):
            world_x = -half + pixel_size * x

            pos = point(world_x, world_y, wall_z)

            r = Ray(ray_origin, normalize(subtract(pos, ray_origin)))
            xs = shape.intersect(r)

            shape_hit = hit(xs)
            if shape_hit is not None:
                hit_point = r.position_at(shape_hit.t)
                normal = shape_hit.object.normal_at(hit_point)
                eye = negate(r.direction)
                px_color = lighting(shape_hit.object.material,
                                    shape_hit.object, light, hit_point, eye,
                                    normal)
                canvas.set_pixel(x, y, px_color)

    with open('render_phong_sphere.ppm', 'w') as out_file:
        out_file.write(canvas.to_ppm())


if __name__ == "__main__":
    main()