week12.py

# Week 12: Turtle Catcher (Capstone Project)
# Goal: Combine all turtle concepts - click targets before time runs out!
# New concepts: Mouse events and continuous game loop with ontimer()

import turtle
import random
import time

# Setup screen
screen = turtle.Screen()
screen.title("Turtle Catcher")
screen.setup(width=700, height=500)

# Create target turtle (what we click on)
target = turtle.Turtle()
target.shape("circle")
target.color("red")
target.penup()
target.speed(0)

# Create display turtle
writer = turtle.Turtle()
writer.hideturtle()
writer.penup()
writer.goto(-330, 210)

# Game variables
score = 0
GAME_SECONDS = 25
start_time = time.time()

# ===== Helper Functions =====

def move_target():
    """Move target to random position"""
    target.goto(random.randint(-320, 320), random.randint(-200, 200))

def draw_ui():
    """Update score and timer display"""
    # Calculate remaining time
    remaining = max(0, int(GAME_SECONDS - (time.time() - start_time)))
    
    # Update display
    writer.clear()
    writer.write(f"Score: {score}   Time: {remaining}", 
                 font=("Arial", 16, "normal"))

def time_up():
    """Check if game time has expired"""
    return (time.time() - start_time) >= GAME_SECONDS

# ===== Event Handler for Mouse Clicks =====

def on_click(x, y):
    """
    Handle mouse click on target
    
    Args:
        x: X coordinate of click
        y: Y coordinate of click
    """
    global score
    
    # Don't allow clicks after game ends
    if time_up():
        return
    
    # Check if click is close enough to target
    # Using distance between click position (x,y) and target position
    if target.distance(x, y) < 25:
        score += 1
        move_target()  # Move to new position
        draw_ui()      # Update display

# ===== Game Loop =====
# This is different from previous games!
# tick() is called repeatedly to update the display

def tick():
    """
    Main game loop - called repeatedly
    This creates continuous updates even without user input
    """
    if time_up():
        # Game over - show message and STOP the loop
        writer.goto(-90, 0)
        writer.write("TIME UP!", font=("Arial", 24, "bold"))
        return  # Don't schedule next tick (loop stops)
    
    # Update UI (refreshes timer)
    draw_ui()
    
    # Schedule next update
    # ontimer(function, milliseconds) calls function after delay
    # 250ms = 0.25 seconds = updates 4 times per second
    screen.ontimer(tick, 250)

# ===== Initialize Game =====

# Connect click event to target turtle
# When target is clicked, on_click() is called with click coordinates
target.onclick(on_click)

# Place target at random starting position
move_target()

# Start the game loop
tick()  # This begins the continuous update cycle

# Keep window open
screen.mainloop()

# ===== Key Concepts =====
# 1. Mouse events: onclick() receives x, y coordinates
# 2. Game loop: tick() → update → schedule next tick → repeat
# 3. ontimer(function, ms) schedules future function call
# 4. Stop loop by NOT scheduling next tick (return early)
# 5. This pattern is used in most real games!

# ===== Difference from Keyboard Games =====
# Keyboard games: Update only when key pressed
# This game: Updates continuously (every 250ms)
# Why? Timer needs to update even when player doesn't click