CA-DONUT: An port of donut.c for the Casio PRIZM!

# CA-DONUT! Coded By nonogamer9
# An Port Of Donut.c For The Casio PRIZM!
import math
import casioplot as cp

theta_spacing = 0.3
phi_spacing = 0.1
R1, R2 = 1, 2
K2 = 5
screen_width, screen_height = 80, 60
K1 = screen_width * K2 * 3 / (8 * (R1 + R2))

TWOPI = 2 * math.pi
THETA_STEPS = int(TWOPI / theta_spacing)
PHI_STEPS = int(TWOPI / phi_spacing)
HALF_WIDTH = screen_width // 2
HALF_HEIGHT = screen_height // 2

sin_table = [math.sin(i * theta_spacing) for i in range(THETA_STEPS)]
cos_table = [math.cos(i * theta_spacing) for i in range(THETA_STEPS)]

def render_frame(A, B):
    cosA, sinA = math.cos(A), math.sin(A)
    cosB, sinB = math.cos(B), math.sin(B)

    cp.clear_screen()
    zbuffer = [[0] * screen_height for _ in range(screen_width)]

    for theta in range(THETA_STEPS):
        costheta = cos_table[theta]
        sintheta = sin_table[theta]

        for phi in range(PHI_STEPS):
            cosphi = math.cos(phi * phi_spacing)
            sinphi = math.sin(phi * phi_spacing)

            circlex = R2 + R1 * costheta
            circley = R1 * sintheta

            x = circlex * (cosB * cosphi + sinA * sinB * sinphi) - circley * cosA * sinB
            y = circlex * (sinB * cosphi - sinA * cosB * sinphi) + circley * cosA * cosB
            z = K2 + cosA * circlex * sinphi + circley * sinA
            ooz = 1 / z

            xp = int(HALF_WIDTH + K1 * ooz * x)
            yp = int(HALF_HEIGHT - K1 * ooz * y)

            if 0 <= xp < screen_width and 0 <= yp < screen_height:
                L = cosphi * costheta * sinB - cosA * costheta * sinphi - sinA * sintheta + cosB * (cosA * sintheta - costheta * sinA * sinphi)

                if L > 0 and ooz > zbuffer[xp][yp]:
                    zbuffer[xp][yp] = ooz
                    brightness = int(L * 255)
                    cp.set_pixel(xp, yp, (brightness, brightness, brightness))

    cp.show_screen()

A, B = 1.0, 1.0
frame_count = 0

while True:
    render_frame(A, B)
    A += 0.08
    B += 0.03
    frame_count += 1

    if frame_count % 5 == 0:
        for _ in range(10000):
            pass

    if frame_count >= 200:
        break