TigerJython

Example: Canon Shooter Game

While our platform game used to turtle itself as the animated object, here we animate the bullet by repainting it over and over at different locations.

Use your mouse to position the canon and click with the mouse to shoot. Once a bullet has been shoot you have to wait until it has completed its trajectory before you can shoot again. This is because we only have a single bullet at a time.

The Source Code

# EXAMPLE FOR A CANON SHOOTER GAME USING THE TURTLE
#
# This is a simple canon shooter game. The objective is to
# position a canon so as to hit the target with a bullet.
# Use your mouse to control the canon's pitch, click to
# shoot.
#
# The target will be repositioned every time you hit it.
#
# Apr-18-2014
#
# (c) 2014, Tobias Kohn
# http://jython.tobiaskohn.ch/
#
from gturtle import *
from math import *
from time import sleep
from random import randint

BACKGROUND = makeColor("sky blue")
BULLETCOLOR = makeColor("yellow")
TARGETCOLOR = makeColor("red")

# Adapt to your turtle's playground size:
MAXX = 440
CANONPOS = -350
GROUNDLEVEL = -250

# Must be smaller than 40:
INITSPEED = 36

### Motion: Moving the bullet ###

# Position and speed of the bullet:
posX = 0
posY = 0
speedX = 0
speedY = 0

def fireBullet(initSpeedX, initSpeedY):
    """Fire the bullet. This function will not return as
       long as the bullet is flying."""
    global posX, posY, speedX, speedY
    posX = CANONPOS
    posY = GROUNDLEVEL + 15
    speedX = initSpeedX
    speedY = initSpeedY
    moveBullet()
    drawCanon()
    while posY > GROUNDLEVEL and posX < MAXX:
        moveBullet()
        if targetHit():
            msgDlg("You hit the target!\nCongratulations!")
            repositionTarget()
            break
        sleep(0.1)

def moveBullet():
    """Move the flying bullet. Recalculate the new position
       and speed according to gravity."""
    global posX, posY, speedX, speedY
    global canonDrawing
    # Wait for the canon to be drawed before drawing the 
    # bullet to avoid artefacts on the screen:
    while canonDrawing:
        sleep(0.001)
    # Erase the present bullet
    setPos(posX, posY)
    setPenColor(BACKGROUND)
    dot(12)
    # Update position and speed
    posX += speedX
    posY += speedY
    speedY -= 1.25
    # Draw the new bullet
    if posY > GROUNDLEVEL+6:
        setPos(posX, posY)
        setPenColor(BULLETCOLOR)
        dot(10)

### Target ###

targetX = 0
targetY = 0

def repositionTarget():
    """Reposition the target at a random position."""
    global targetX, targetY
    if targetX > 0:
        setPos(targetX, targetY)
        setPenColor(BACKGROUND)
        dot(60)
    targetX = -CANONPOS - randint(0, 50) -20
    targetY = randint(GROUNDLEVEL, -GROUNDLEVEL // 2 - 20)+20
    setPos(targetX, targetY)
    setPenColor(TARGETCOLOR)
    dot(40)
    setPenColor(makeColor("white"))
    dot(25)
    setPenColor(TARGETCOLOR)
    dot(10)

def targetHit():
    """Check if the bullet hit the target."""
    dist = sqrt((posX - targetX)**2 + (posY - targetY)**2)
    return (dist <= 25)

### Canon ###

canonAngle = 0
canonDrawing = False

def drawCanon():
    """Redraw the canon in the right angle.."""
    global canonAngle, canonDrawing
    canonDrawing = True
    setPos(CANONPOS+15, GROUNDLEVEL+30)
    setPenColor(BACKGROUND)
    dot(60)
    setPos(CANONPOS, GROUNDLEVEL+15)
    heading(canonAngle)
    penWidth(10)
    setPenColor(makeColor("#1A1A1A"))
    forward(20)
    setPos(CANONPOS, GROUNDLEVEL+15)
    setPenColor(makeColor("black"))
    dot(20)
    canonDrawing = False

### Mouse Handler ###

def onMouseClick(x, y):
    angle = radians(canonAngle)
    fireBullet(INITSPEED * sin(angle), INITSPEED * cos(angle))

def onMouseMove(x, y):
    global canonAngle
    deltaX = x - CANONPOS
    deltaY = y - GROUNDLEVEL
    if deltaX >= 0 and deltaY >= 0:
        canonAngle = degrees(atan2(deltaX, deltaY))
        drawCanon()

# Auxiliary Callback for the "mouseMoved"-event
def mouseMovedCallback(e):
    onMouseMove(toTurtleX(e.getX()), toTurtleY(e.getY()))

### MAIN ###
makeTurtle(mouseMoved = mouseMovedCallback,
           mouseHitX = onMouseClick)
# Draw the background
hideTurtle()
clear(BACKGROUND)
setPenColor(makeColor("dark green"))
penWidth(10)
setPos(-MAXX, GROUNDLEVEL-5)
moveTo(MAXX, GROUNDLEVEL-5)
setFillColor(makeColor("saddle brown"))
setPos(0, GROUNDLEVEL-10)
fill()
drawCanon()
repositionTarget()