I’m making a simple platform game. You jump up until you get to the “end” platform. I am having a couple of problems. My first real problem is having ideas but I don’t know how to implement them. I get the gist of what I need, but anything past that I am lost. Here’s how I would like the game to work. When the player jumps higher than the stage, I want it to scroll up to a new portion of the level. It gives the effect of climbing a tower. For this, I know I need to make a couple of stages and then store them into an array (that way when the player reaches the top of the stage and it loads a new portion, it would cycle through the array, randomly, and select a new portion. Making the game different almost every time.) I also would like the game to scroll slowly upwards, giving the player some sort of danger other than falling off the bottom of the stage and if the bottom of the stage overlaps the player; he loses. This game also uses Newtonian physics. Also, I get this weird error when I try to instantiate my stageOne screen. I think it has something to do with the Player_Platform class. The var _collisionArea might be the problem. It is linked to the player symble which is inside the mcStageOne symble. Sorry for the long post.
tl;dr : I want to create a game that is a platform. The game scrolls upwards trying to kill you. If you reach the top of the flash stage, it loads a new portion of the stage randomly. I have decent ideas, but can’t implement them to save my life.
Main_Game_Experiment Class
package
{
import flash.display.MovieClip;
import flash.events.Event;
import flash.media.Sound;
import flash.net.URLRequest;
import flash.geom.Point;
import mcStageOne;
public class Main_Game_Experiment extends MovieClip
{
private var _stages:Array;
private var stageOne:mcStageOne;
//private var nextStage:Boolean;
//Constructor function
public function Main_Game_Experiment()
{
stageOne = new mcStageOne();
addChild(stageOne);
addEventListener(Event.ENTER_FRAME, onEnterFrame);
//setChildIndex(water, numChildren - 1);
//setChildIndex(player, numChildren - 1);
for (var i:int = 0; i < numChildren; i++)
{
trace(i + ". " + getChildAt(i).name);
}
//Initialize array and variables
//stages = new Array();
//stages = [];
//nextStage = false
}
private function onEnterFrame(event:Event):void
{
//Player vs platform collision
for (var i:int = 0; i <= 4; i++)
{
Collision.playerAndPlatform(stageOne.player, stageOne.platform["platform" + i], 0.2, 0);//I think the error for stageOne is here
//trace("platform" + i);
}
}
}
}
Here is the code for the Player_Platform Class
package
{
import flash.display.MovieClip;
import flash.events.KeyboardEvent;
import flash.ui.Keyboard;
import flash.events.Event;
public class Player_Platform extends MovieClip
{
//Constants
private const FRICTION:Number = 0.60;
private const SPEED_LIMIT:int = 7;
private const GRAVITY:Number = 0.8;
private const ACCELERATION:Number = 1;
private const BOUNCE:Number = -0.3;
private const JUMP_FORCE:Number = -16;
//Variables:
private var _vx:Number;
private var _vy:Number;
private var _accelerationX:Number;
private var _accelerationY:Number;
private var _frictionX:Number;
private var _isOnGround:Boolean;
private var _bounceX:Number;
private var _bounceY:Number;
private var _collisionArea:MovieClip;
public function Player_Platform()
{
_vx = 0;
_vy = 0;
_accelerationX = 0;
_accelerationY = 0;
_frictionX = FRICTION;
_isOnGround = undefined;
_bounceX = 0;
_bounceY = 0;
_collisionArea = this.hitBox;//Or the problem for stageOne occures here.
//Add stage event listeners
stage.addEventListener(KeyboardEvent.KEY_DOWN,onKeyDown);
stage.addEventListener(KeyboardEvent.KEY_UP,onKeyUp);
addEventListener(Event.ENTER_FRAME, onEnterFrame);
}
private function onKeyDown(event:KeyboardEvent):void
{
//Remove friction if the object is moving
_frictionX = 1;
if (event.keyCode == Keyboard.LEFT)
{
_accelerationX = -ACCELERATION;
}
if (event.keyCode == Keyboard.RIGHT)
{
_accelerationX = ACCELERATION;
}
if ((event.keyCode == Keyboard.UP)|| (event.keyCode == Keyboard.SPACE))
{
if (_isOnGround)
{
_accelerationY = JUMP_FORCE;
_isOnGround = false;
}
}
}
private function onKeyUp(event:KeyboardEvent):void
{
if ((event.keyCode == Keyboard.LEFT)
|| (event.keyCode == Keyboard.RIGHT))
{
_accelerationX = 0;
//Apply friction when the keys are no longer being pressed
_frictionX = FRICTION;
}
if ((event.keyCode == Keyboard.UP)
|| (event.keyCode == Keyboard.SPACE))
{
_accelerationY = 0;
}
}
private function onEnterFrame(event:Event):void
{
//Initialize local variables
var playerHalfWidth:uint = _collisionArea.width / 2;
var playerHalfHeight:uint = _collisionArea.height / 2;
//Apply Acceleration
_vx += _accelerationX;
if (_vx > SPEED_LIMIT)
{
_vx = SPEED_LIMIT;
}
if (_vx < -SPEED_LIMIT)
{
_vx = -SPEED_LIMIT;
}
_vy += _accelerationY;
if (_vy > SPEED_LIMIT * 3)
{
_vy = SPEED_LIMIT * 3;
}
//No speed limit for jumping
//Apply Friction
if (_isOnGround)
{
_vx *= _frictionX;
}
if (Math.abs(_vx) < 0.1)
{
_vx = 0;
}
if (Math.abs(_vy) < 0.1)
{
_vy = 0;
}
//Apply Gravity
_vy += GRAVITY;
//Apply Bounce from collision with platforms
x += bounceX;
y += bounceY;
//Move the player
x += _vx;
y += _vy;
//Reset platform bounce values so that they
//don't compound with the next collision
_bounceX = 0;
_bounceY = 0;
//Prevent object from moving up if
//it's not on the ground
if (! _isOnGround)
{
_accelerationY = 0;
}
/*Flap ears only when going up
if (_vy >= 0)
{
_isOnGround = false;
//_directionY = "down"
}*/
//Stage boundaries
if (x + playerHalfWidth > stage.stageWidth)
{
_vx = 0;
x=stage.stageWidth - playerHalfWidth;
}
else if (x - playerHalfWidth < 0)
{
_vx = 0;
x = 0+playerHalfWidth;
}
}
//Getters and Setters
public function get isOnGround():Boolean
{
return _isOnGround;
}
public function set isOnGround(onGround:Boolean):void
{
_isOnGround = onGround;
}
public function set vx(vxValue:Number):void
{
_vx = vxValue;
}
public function get vx():Number
{
return _vx;
}
public function set vy(vyValue:Number):void
{
_vy = vyValue;
}
public function get vy():Number
{
return _vy;
}
public function get bounceX():Number
{
return _bounceX;
}
public function set bounceX(bounceXValue:Number):void
{
_bounceX = bounceXValue;
}
public function get bounceY():Number
{
return _bounceY;
}
public function set bounceY(bounceYValue:Number):void
{
_bounceY = bounceYValue;
}
public function get collisionArea():MovieClip
{
return _collisionArea;
}
}
}
Here is the code for the Collision Class
package
{
import flash.display.MovieClip;
import flash.geom.Point;
public class Collision
{
public function Collision()
{
}
//Block objects
static public function block(objectA:MovieClip, objectB:MovieClip):void
{
var objectA_Halfwidth:Number = objectA.width / 2;
var objectA_Halfheight:Number = objectA.height / 2;
var objectB_Halfwidth:Number = objectB.width / 2;
var objectB_Halfheight:Number = objectB.height / 2;
var dx:Number = objectB.x - objectA.x;
var ox:Number = objectB_Halfwidth + objectA_Halfwidth - Math.abs(dx);
if (ox > 0)
{
var dy:Number = objectA.y - objectB.y;
var oy:Number = objectB_Halfheight + objectA_Halfheight - Math.abs(dy);
if (oy > 0)
{
if (ox < oy)
{
if (dx < 0)
{
//Collision on right
oy = 0;
}
else
{
//Collision on left
oy = 0;
ox *= -1;
}
}
else
{
if (dy < 0)
{
//Collision on Top
ox = 0;
oy *= -1;
}
else
{
//Collision on Bottom
ox = 0;
}
}
//Use the calculated x and y overlaps to
//Move objectA out of the collision
objectA.x += ox;
objectA.y += oy;
}
}
}
//General purpose method for testing Axis-based collisions. Returns true or False
static public function test(objectA:Object,objectB:Object):Boolean
{
var objectA_Halfwidth=objectA.width/2;
var objectA_Halfheight=objectA.height/2;
var objectB_Halfwidth=objectB.width/2;
var objectB_Halfheight=objectB.height/2;
var dx=objectB.x-objectA.x;
var ox=objectB_Halfwidth+objectA_Halfwidth-Math.abs(dx);
if (0<ox)
{
var dy=objectA.y-objectB.y;
var oy=objectB_Halfheight+objectA_Halfheight-Math.abs(dy);
if (0<oy)
{
return true;
}
}
else
{
return false;
}
return false;
}
//Collisions between the player and platform
static public function playerAndPlatform(player:MovieClip, platform:MovieClip, bounce:Number, friction:Number):void
{
//This method requires the following getter and
//setter properties in the player object:
//objectIsOnGround:Boolean, vx:Number, vy:Number,
//bounceX:Number, bounceY:Number
//Declare variables needed for the player's
//position and dimensions
var player_Halfwidth:Number;
var player_Halfheight:Number;
var player_X:Number;
var player_Y:Number
//Decalre variables needed for the physics calculations
var bounceX:Number;
var bounceY:Number;
var frictionX:Number;
var frictionY:Number;
//Find out whether the player object has a collisionArea
//subobject defined
if(player.collisionArea != null)
{
//If it does, find out its width and height
player_Halfwidth = player.collisionArea.width / 2;
player_Halfheight = player.collisionArea.height / 2;
//Convert the collisionArea's local x,y coordinates to global coordinates
var player_Position:Point = new Point(player.collisionArea.x, player.collisionArea.y);
player_X = player.localToGlobal(player_Position).x;
player_Y = player.localToGlobal(player_Position).y;
}
else
{
//If there's no collisionArea subobject
//Use the player's main height, width, x and y
player_Halfwidth = player.width / 2;
player_Halfheight = player.height / 2;
player_X = player.x;
player_Y = player.y;
}
//Find the platform's dimensions
var platform_Halfwidth:Number = platform.width / 2;
var platform_Halfheight:Number = platform.height / 2;
//Find the distance between the player and platfrom on the x axis
var dx:Number = platform.x - player_X;
//Find the amount of overlap on the x axis
var ox:Number = platform_Halfwidth + player_Halfwidth - Math.abs(dx);
//Check for a collision on the x axis
if (ox > 0)
{
//If the objects overlap on the x axis, a collision might be occuring
//Define the variables you need to check for a collision on the y axis
var dy:Number = player.y - platform.y;
var oy:Number = platform_Halfheight + player_Halfheight - Math.abs(dy);
//Check for a y axis collision. We know a collision must be
//occuring if there's a collision on both the x and y axis
if (oy > 0)
{
//Yes, a collision is occuring!
//Now you need to find out on which side
//of the platform it's occuring on.
if (ox < oy)
{
if (dx < 0)
{
//Collision on right
oy = 0;
dx = 1;
dy = 0
}
else
{
//Collision on left
oy = 0;
ox *= -1;
dx = -1;
dy = 0
}
}
else
{
if (dy < 0)
{
//Collision on Top
ox = 0;
oy *= -1;
dx = 0;
dy = -1;
//set the player's isOnGround property to
//true to enable jumping
player.isOnGround = true;
}
else
{
//Collision on Bottom
ox = 0;
dx = 0;
dy = 1;
}
}
//Find the direction of the collision ("dot product")
var directionOfCollision:Number = player.vx * dx + player.vy * dy;
//Calculate the new direction for the bounce ("projection")
var newDirection_X:Number = directionOfCollision * dx;
var newDirection_Y:Number = directionOfCollision * dy;
//Find the "tangent velocity":
//the speed in the direction that the object is moving.
//It's used for calculating additional platform friction.
var tangent_Vx:Number = player.vx - newDirection_X;
var tangent_Vy:Number = player.vy - newDirection_Y;
//Apply collision forces if the object is moving into a collision
if (directionOfCollision < 0)
{
//Calculate the friction
frictionX = tangent_Vx * friction;
frictionY = tangent_Vy * friction;
//Calculate the amount of bounce
bounceX = newDirection_X * bounce;
bounceY = newDirection_Y * bounce;
}
else
{
//Prevent forces from being applied if the object is
//moving out of a collision
bounceX = 0;
bounceY = 0;
frictionX = 0;
frictionY = 0;
}
//Apply platform friction
player.vx += ox - frictionX;
player.vy += oy - frictionY;
//Move the player out of the collision
player.x += ox;
player.y += oy;
//Bounce the player off the platform
player.bounceX = bounceX;
player.bounceY = bounceY;
}
}
}
}
}
