399 lines
18 KiB
Python
399 lines
18 KiB
Python
#!/usr/bin/env python
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# Author: Shao Zhang, Phil Saltzman, and Greg Lindley
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# Last Updated: 2015-03-13
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#
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# This tutorial demonstrates the use of tasks. A task is a function that
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# gets called once every frame. They are good for things that need to be
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# updated very often. In the case of asteroids, we use tasks to update
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# the positions of all the objects, and to check if the bullets or the
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# ship have hit the asteroids.
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#
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# Note: This definitely a complicated example. Tasks are the cores of
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# most games so it seemed appropriate to show what a full game in Panda
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# could look like.
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from direct.showbase.ShowBase import ShowBase
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from panda3d.core import TextNode, TransparencyAttrib
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from panda3d.core import LPoint3, LVector3
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from direct.gui.OnscreenText import OnscreenText
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from direct.task.Task import Task
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from math import sin, cos, pi
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from random import randint, choice, random
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from direct.interval.MetaInterval import Sequence
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from direct.interval.FunctionInterval import Wait, Func
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import sys
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# Constants that will control the behavior of the game. It is good to
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# group constants like this so that they can be changed once without
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# having to find everywhere they are used in code
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SPRITE_POS = 55 # At default field of view and a depth of 55, the screen
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# dimensions is 40x30 units
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SCREEN_X = 20 # Screen goes from -20 to 20 on X
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SCREEN_Y = 15 # Screen goes from -15 to 15 on Y
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TURN_RATE = 360 # Degrees ship can turn in 1 second
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ACCELERATION = 10 # Ship acceleration in units/sec/sec
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MAX_VEL = 6 # Maximum ship velocity in units/sec
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MAX_VEL_SQ = MAX_VEL ** 2 # Square of the ship velocity
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DEG_TO_RAD = pi / 180 # translates degrees to radians for sin and cos
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BULLET_LIFE = 2 # How long bullets stay on screen before removed
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BULLET_REPEAT = .2 # How often bullets can be fired
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BULLET_SPEED = 10 # Speed bullets move
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AST_INIT_VEL = 1 # Velocity of the largest asteroids
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AST_INIT_SCALE = 3 # Initial asteroid scale
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AST_VEL_SCALE = 2.2 # How much asteroid speed multiplies when broken up
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AST_SIZE_SCALE = .6 # How much asteroid scale changes when broken up
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AST_MIN_SCALE = 1.1 # If and asteroid is smaller than this and is hit,
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# it disapears instead of splitting up
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# This helps reduce the amount of code used by loading objects, since all of
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# the objects are pretty much the same.
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def loadObject(tex=None, pos=LPoint3(0, 0), depth=SPRITE_POS, scale=1,
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transparency=True):
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# Every object uses the plane model and is parented to the camera
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# so that it faces the screen.
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obj = loader.loadModel("models/plane")
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obj.reparentTo(camera)
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# Set the initial position and scale.
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obj.setPos(pos.getX(), depth, pos.getY())
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obj.setScale(scale)
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# This tells Panda not to worry about the order that things are drawn in
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# (ie. disable Z-testing). This prevents an effect known as Z-fighting.
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obj.setBin("unsorted", 0)
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obj.setDepthTest(False)
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if transparency:
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# Enable transparency blending.
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obj.setTransparency(TransparencyAttrib.MAlpha)
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if tex:
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# Load and set the requested texture.
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tex = loader.loadTexture("textures/" + tex)
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obj.setTexture(tex, 1)
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return obj
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# Macro-like function used to reduce the amount to code needed to create the
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# on screen instructions
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def genLabelText(text, i):
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return OnscreenText(text=text, parent=base.a2dTopLeft, pos=(0.07, -.06 * i - 0.1),
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fg=(1, 1, 1, 1), align=TextNode.ALeft, shadow=(0, 0, 0, 0.5), scale=.05)
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class AsteroidsDemo(ShowBase):
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def __init__(self):
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# Initialize the ShowBase class from which we inherit, which will
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# create a window and set up everything we need for rendering into it.
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ShowBase.__init__(self)
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# This code puts the standard title and instruction text on screen
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self.title = OnscreenText(text="Panda3D: Tutorial - Tasks",
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parent=base.a2dBottomRight, scale=.07,
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align=TextNode.ARight, pos=(-0.1, 0.1),
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fg=(1, 1, 1, 1), shadow=(0, 0, 0, 0.5))
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self.escapeText = genLabelText("ESC: Quit", 0)
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self.leftkeyText = genLabelText("[Left Arrow]: Turn Left (CCW)", 1)
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self.rightkeyText = genLabelText("[Right Arrow]: Turn Right (CW)", 2)
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self.upkeyText = genLabelText("[Up Arrow]: Accelerate", 3)
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self.spacekeyText = genLabelText("[Space Bar]: Fire", 4)
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# Disable default mouse-based camera control. This is a method on the
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# ShowBase class from which we inherit.
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self.disableMouse()
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# Load the background starfield.
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self.setBackgroundColor((0, 0, 0, 1))
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self.bg = loadObject("stars.jpg", scale=146, depth=200,
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transparency=False)
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# Load the ship and set its initial velocity.
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self.ship = loadObject("ship.png")
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self.setVelocity(self.ship, LVector3.zero())
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# A dictionary of what keys are currently being pressed
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# The key events update this list, and our task will query it as input
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self.keys = {"turnLeft": 0, "turnRight": 0,
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"accel": 0, "fire": 0}
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self.accept("escape", sys.exit) # Escape quits
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# Other keys events set the appropriate value in our key dictionary
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self.accept("arrow_left", self.setKey, ["turnLeft", 1])
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self.accept("arrow_left-up", self.setKey, ["turnLeft", 0])
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self.accept("arrow_right", self.setKey, ["turnRight", 1])
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self.accept("arrow_right-up", self.setKey, ["turnRight", 0])
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self.accept("arrow_up", self.setKey, ["accel", 1])
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self.accept("arrow_up-up", self.setKey, ["accel", 0])
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self.accept("space", self.setKey, ["fire", 1])
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# Now we create the task. taskMgr is the task manager that actually
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# calls the function each frame. The add method creates a new task.
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# The first argument is the function to be called, and the second
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# argument is the name for the task. It returns a task object which
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# is passed to the function each frame.
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self.gameTask = taskMgr.add(self.gameLoop, "gameLoop")
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# Stores the time at which the next bullet may be fired.
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self.nextBullet = 0.0
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# This list will stored fired bullets.
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self.bullets = []
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# Complete initialization by spawning the asteroids.
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self.spawnAsteroids()
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# As described earlier, this simply sets a key in the self.keys dictionary
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# to the given value.
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def setKey(self, key, val):
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self.keys[key] = val
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def setVelocity(self, obj, val):
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obj.setPythonTag("velocity", val)
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def getVelocity(self, obj):
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return obj.getPythonTag("velocity")
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def setExpires(self, obj, val):
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obj.setPythonTag("expires", val)
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def getExpires(self, obj):
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return obj.getPythonTag("expires")
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def spawnAsteroids(self):
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# Control variable for if the ship is alive
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self.alive = True
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self.asteroids = [] # List that will contain our asteroids
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for i in range(10):
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# This loads an asteroid. The texture chosen is random
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# from "asteroid1.png" to "asteroid3.png".
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asteroid = loadObject("asteroid%d.png" % (randint(1, 3)),
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scale=AST_INIT_SCALE)
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self.asteroids.append(asteroid)
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# This is kind of a hack, but it keeps the asteroids from spawning
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# near the player. It creates the list (-20, -19 ... -5, 5, 6, 7,
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# ... 20) and chooses a value from it. Since the player starts at 0
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# and this list doesn't contain anything from -4 to 4, it won't be
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# close to the player.
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asteroid.setX(choice(tuple(range(-SCREEN_X, -5)) + tuple(range(5, SCREEN_X))))
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# Same thing for Y
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asteroid.setZ(choice(tuple(range(-SCREEN_Y, -5)) + tuple(range(5, SCREEN_Y))))
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# Heading is a random angle in radians
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heading = random() * 2 * pi
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# Converts the heading to a vector and multiplies it by speed to
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# get a velocity vector
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v = LVector3(sin(heading), 0, cos(heading)) * AST_INIT_VEL
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self.setVelocity(self.asteroids[i], v)
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# This is our main task function, which does all of the per-frame
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# processing. It takes in self like all functions in a class, and task,
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# the task object returned by taskMgr.
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def gameLoop(self, task):
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# Get the time elapsed since the next frame. We need this for our
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# distance and velocity calculations.
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dt = globalClock.getDt()
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# If the ship is not alive, do nothing. Tasks return Task.cont to
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# signify that the task should continue running. If Task.done were
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# returned instead, the task would be removed and would no longer be
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# called every frame.
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if not self.alive:
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return Task.cont
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# update ship position
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self.updateShip(dt)
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# check to see if the ship can fire
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if self.keys["fire"] and task.time > self.nextBullet:
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self.fire(task.time) # If so, call the fire function
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# And disable firing for a bit
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self.nextBullet = task.time + BULLET_REPEAT
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# Remove the fire flag until the next spacebar press
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self.keys["fire"] = 0
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# update asteroids
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for obj in self.asteroids:
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self.updatePos(obj, dt)
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# update bullets
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newBulletArray = []
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for obj in self.bullets:
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self.updatePos(obj, dt) # Update the bullet
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# Bullets have an experation time (see definition of fire)
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# If a bullet has not expired, add it to the new bullet list so
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# that it will continue to exist.
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if self.getExpires(obj) > task.time:
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newBulletArray.append(obj)
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else:
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obj.removeNode() # Otherwise, remove it from the scene.
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# Set the bullet array to be the newly updated array
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self.bullets = newBulletArray
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# Check bullet collision with asteroids
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# In short, it checks every bullet against every asteroid. This is
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# quite slow. A big optimization would be to sort the objects left to
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# right and check only if they overlap. Framerate can go way down if
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# there are many bullets on screen, but for the most part it's okay.
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for bullet in self.bullets:
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# This range statement makes it step though the asteroid list
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# backwards. This is because if an asteroid is removed, the
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# elements after it will change position in the list. If you go
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# backwards, the length stays constant.
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for i in range(len(self.asteroids) - 1, -1, -1):
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asteroid = self.asteroids[i]
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# Panda's collision detection is more complicated than we need
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# here. This is the basic sphere collision check. If the
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# distance between the object centers is less than sum of the
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# radii of the two objects, then we have a collision. We use
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# lengthSquared() since it is faster than length().
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if ((bullet.getPos() - asteroid.getPos()).lengthSquared() <
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(((bullet.getScale().getX() + asteroid.getScale().getX())
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* .5) ** 2)):
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# Schedule the bullet for removal
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self.setExpires(bullet, 0)
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self.asteroidHit(i) # Handle the hit
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# Now we do the same collision pass for the ship
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shipSize = self.ship.getScale().getX()
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for ast in self.asteroids:
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# Same sphere collision check for the ship vs. the asteroid
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if ((self.ship.getPos() - ast.getPos()).lengthSquared() <
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(((shipSize + ast.getScale().getX()) * .5) ** 2)):
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# If there is a hit, clear the screen and schedule a restart
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self.alive = False # Ship is no longer alive
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# Remove every object in asteroids and bullets from the scene
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for i in self.asteroids + self.bullets:
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i.removeNode()
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self.bullets = [] # Clear the bullet list
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self.ship.hide() # Hide the ship
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# Reset the velocity
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self.setVelocity(self.ship, LVector3(0, 0, 0))
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Sequence(Wait(2), # Wait 2 seconds
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Func(self.ship.setR, 0), # Reset heading
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Func(self.ship.setX, 0), # Reset position X
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# Reset position Y (Z for Panda)
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Func(self.ship.setZ, 0),
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Func(self.ship.show), # Show the ship
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Func(self.spawnAsteroids)).start() # Remake asteroids
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return Task.cont
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# If the player has successfully destroyed all asteroids, respawn them
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if len(self.asteroids) == 0:
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self.spawnAsteroids()
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return Task.cont # Since every return is Task.cont, the task will
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# continue indefinitely
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# Updates the positions of objects
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def updatePos(self, obj, dt):
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vel = self.getVelocity(obj)
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newPos = obj.getPos() + (vel * dt)
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# Check if the object is out of bounds. If so, wrap it
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radius = .5 * obj.getScale().getX()
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if newPos.getX() - radius > SCREEN_X:
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newPos.setX(-SCREEN_X)
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elif newPos.getX() + radius < -SCREEN_X:
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newPos.setX(SCREEN_X)
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if newPos.getZ() - radius > SCREEN_Y:
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newPos.setZ(-SCREEN_Y)
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elif newPos.getZ() + radius < -SCREEN_Y:
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newPos.setZ(SCREEN_Y)
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obj.setPos(newPos)
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# The handler when an asteroid is hit by a bullet
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def asteroidHit(self, index):
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# If the asteroid is small it is simply removed
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if self.asteroids[index].getScale().getX() <= AST_MIN_SCALE:
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self.asteroids[index].removeNode()
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# Remove the asteroid from the list of asteroids.
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del self.asteroids[index]
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else:
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# If it is big enough, divide it up into little asteroids.
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# First we update the current asteroid.
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asteroid = self.asteroids[index]
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newScale = asteroid.getScale().getX() * AST_SIZE_SCALE
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asteroid.setScale(newScale) # Rescale it
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# The new direction is chosen as perpendicular to the old direction
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# This is determined using the cross product, which returns a
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# vector perpendicular to the two input vectors. By crossing
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# velocity with a vector that goes into the screen, we get a vector
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# that is orthagonal to the original velocity in the screen plane.
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vel = self.getVelocity(asteroid)
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speed = vel.length() * AST_VEL_SCALE
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vel.normalize()
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vel = LVector3(0, 1, 0).cross(vel)
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vel *= speed
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self.setVelocity(asteroid, vel)
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# Now we create a new asteroid identical to the current one
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newAst = loadObject(scale=newScale)
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self.setVelocity(newAst, vel * -1)
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newAst.setPos(asteroid.getPos())
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newAst.setTexture(asteroid.getTexture(), 1)
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self.asteroids.append(newAst)
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# This updates the ship's position. This is similar to the general update
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# but takes into account turn and thrust
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def updateShip(self, dt):
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heading = self.ship.getR() # Heading is the roll value for this model
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# Change heading if left or right is being pressed
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if self.keys["turnRight"]:
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heading += dt * TURN_RATE
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self.ship.setR(heading % 360)
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elif self.keys["turnLeft"]:
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heading -= dt * TURN_RATE
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self.ship.setR(heading % 360)
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# Thrust causes acceleration in the direction the ship is currently
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# facing
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if self.keys["accel"]:
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heading_rad = DEG_TO_RAD * heading
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# This builds a new velocity vector and adds it to the current one
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# relative to the camera, the screen in Panda is the XZ plane.
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# Therefore all of our Y values in our velocities are 0 to signify
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# no change in that direction.
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newVel = \
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LVector3(sin(heading_rad), 0, cos(heading_rad)) * ACCELERATION * dt
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newVel += self.getVelocity(self.ship)
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# Clamps the new velocity to the maximum speed. lengthSquared() is
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# used again since it is faster than length()
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if newVel.lengthSquared() > MAX_VEL_SQ:
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newVel.normalize()
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newVel *= MAX_VEL
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self.setVelocity(self.ship, newVel)
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# Finally, update the position as with any other object
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self.updatePos(self.ship, dt)
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# Creates a bullet and adds it to the bullet list
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def fire(self, time):
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direction = DEG_TO_RAD * self.ship.getR()
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pos = self.ship.getPos()
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bullet = loadObject("bullet.png", scale=.2) # Create the object
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bullet.setPos(pos)
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# Velocity is in relation to the ship
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vel = (self.getVelocity(self.ship) +
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(LVector3(sin(direction), 0, cos(direction)) *
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BULLET_SPEED))
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self.setVelocity(bullet, vel)
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# Set the bullet expiration time to be a certain amount past the
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# current time
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self.setExpires(bullet, time + BULLET_LIFE)
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# Finally, add the new bullet to the list
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self.bullets.append(bullet)
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# We now have everything we need. Make an instance of the class and start
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# 3D rendering
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demo = AsteroidsDemo()
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demo.run()
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