# This work is licensed under the MIT license.
# Copyright (c) 2013-2023 OpenMV LLC. All rights reserved.
# https://github.com/openmv/openmv/blob/master/LICENSE
#
# Black Grayscale Line Following Example
#
# Making a line following robot requires a lot of effort. This example script
# shows how to do the machine vision part of the line following robot. You
# can use the output from this script to drive a differential drive robot to
# follow a line. This script just generates a single turn value that tells
# your robot to go left or right.
#
# For this script to work properly you should point the camera at a line at a
# 45 or so degree angle. Please make sure that only the line is within the
# camera's field of view.

import sensor
import time
import math

# Tracks a black line. Use [(128, 255)] for a tracking a white line.
GRAYSCALE_THRESHOLD = [(0, 64)]

# Each roi is (x, y, w, h). The line detection algorithm will try to find the
# centroid of the largest blob in each roi. The x position of the centroids
# will then be averaged with different weights where the most weight is assigned
# to the roi near the bottom of the image and less to the next roi and so on.
ROIS = [  # [ROI, weight]
    (0, 100, 160, 20, 0.7),  # You'll need to tweak the weights for your app
    (0, 50, 160, 20, 0.3),  # depending on how your robot is setup.
    (0, 0, 160, 20, 0.1),
]

# Compute the weight divisor (we're computing this so you don't have to make weights add to 1).
weight_sum = 0
for r in ROIS:
    weight_sum += r[4]  # r[4] is the roi weight.

# Camera setup...
sensor.reset()  # Initialize the camera sensor.
sensor.set_pixformat(sensor.GRAYSCALE)  # use grayscale.
sensor.set_framesize(sensor.QQVGA)  # use QQVGA for speed.
sensor.skip_frames(time=2000)  # Let new settings take affect.
sensor.set_auto_gain(False)  # must be turned off for color tracking
sensor.set_auto_whitebal(False)  # must be turned off for color tracking
clock = time.clock()  # Tracks FPS.

while True:
    cl