So I am currently creating a small game that contains 25 total sprites in one Scene. 1 sprite is the player and the rest are enemy sprites.
What I am trying to do is set the position of the 24 enemy sprites to their own unique areas. This can be easily done by simply doing sprite.setPosition(x,y) but this would mean I would have to write 24 different setPosition statements.
My sprites are all stored in an ArrayList which adds the 24 sprites to the list which are then rendered 24 times in the render() method. Currently all 24 sprites are rendered at 0,0.
Is there a simpler and more efficient way to set each sprites position which can then be updated to work with deltatime to move the sprite.
You could store each of the sprites in an array, then simply set the positions of all of them to be on some random position on the radius of an expanding circle as you iterate over all the enemy sprites:
...
private Sprite[] enemies;
...
public void positionSprites() {
for(int i = 0; i < enemies.length; i++) {
//Gets the enemy from the array.
Sprite enemy = enemies[i];
//Generates a random angle between 0 and 2pi in radians to move the sprite to.
double randAngle = 2 * Math.PI * Math.random();
//Calculates the radius of the circle to be the (iteration count + 1) * the diagonal size of the sprites to prevent them from overlapping.
double radius = (i + 1) * Math.sqrt(Math.pow(enemy.getWidth(), 2) + Math.pow(enemy.getHeight(), 2));
//Calculates the position the enemy at the random angle along the circle.
float x = (float) radius * Math.cos(angle), y = (float) radius * Math.sin(angle);
//Sets the enemy position to the new position.
enemy.setPosition(x, y);
}
}
Related
I want to make a tracing game. I want my circle to follow the path as the user traces the letter (path of the letter). The user can not go back to the area which is already traced
import flash.events.Event;
import flash.geom.Point;
var i: Number;
var size: int = 80;
var down: Boolean = false;
var up: Boolean = true;
var inside: Boolean = true;
var outside: Boolean = true;
var circle: Shape = new Shape();
stage.addEventListener(Event.ENTER_FRAME, loop);
stage.addEventListener(MouseEvent.MOUSE_UP, mouseup);
char.addEventListener(MouseEvent.MOUSE_DOWN, mousedown);
function loop(e: Event) {
if (down == true) {
// Checks if mouse pointer is on path i.e 'S' alphabet
if (s.hitTestPoint(stage.mouseX, stage.mouseY, true)) {
inside = true;
outside = true;
var point: Point = maskobj.globalToLocal(new Point(stage.mouseX, stage.mouseY));
var point2: Point = new Point();
//Checks if mouse pointer is completely outside of drawn area
for (i = 0; i < 2 * Math.PI; i += (2 * Math.PI) / 10) {
point2.x = stage.mouseX + (size / 3) * Math.cos(i);
point2.y = stage.mouseY + (size / 3) * Math.sin(i);
if ((maskobj.hitTestPoint(point2.x, point2.y, true))) {
outside = false;
break;
}
}
//Checks if mouse pointer is completely inside drawn area
for (i = 0; i < 2 * Math.PI; i += (2 * Math.PI) / 10) {
point2.x = stage.mouseX + (size / 3) * Math.cos(i);
point2.y = stage.mouseY + (size / 3) * Math.sin(i);
if (!(maskobj.hitTestPoint(point2.x, point2.y, true))) {
inside = false;
break;
}
}
//Character will be moved only if mouse position not to far from current position
if (outside == false) {
if (inside == false) {
//Increases drawn area by drawing a circle shape in 'maskobj' MovieClip
circle.graphics.beginFill(0x0000ff);
circle.graphics.drawCircle(point.x, point.y, size);
circle.graphics.endFill();
maskobj.addChild(circle);
//Moves character to new position
char.x = stage.mouseX;
char.y = stage.mouseY;
}
}
}
}
}
function mouseup(e: MouseEvent): void {
up = true;
down = false;
}
function mousedown(e: MouseEvent): void {
down = true;
up = false;
}
When I trace the path,the motion is not smooth. Can someone please suggest a way to make the motion smooth OR suggest another way to achieve the same. Thank you in advance.
I've created a drawing game before that allowed the user to draw a path.
Not sure why Wicked's answer was down-voted, as the first thing you need to do is to use the highest frame rate that you can get away with. The higher the frame rate, the smoother your curve.
I see that your code draws a circle at the current position if the conditions are met. It might be better to draw a line from the last point.x/point.y to the current one instead of just a circle, so that you don't have any holes in your path.
I couldn't get around the fact that the line was jagged (a series of straight lines) as it was being drawn, but as soon as the user lifted their finger I was able to take the points along the line they had drawn and replace them with a smooth bezier Path (a series of simple bezier curves), which worked well. You could also do this on-the-fly once you have 3 points (you need 3 points to draw a curve).
Here is a good reference on how to achieve this, with theory and code samples. See further down the page for bezier paths. You'll need to convert to AS3, but it shouldn't be difficult.
Another tip is to do as little calculation as possible within the ENTER_FRAME. You could pre-calculate the two values used by your loops (2 * Math.PI) and ((2 * Math.PI) / 10) as these are constants. You could also calculate (size/3) once at the top of the function, and especially pre-calculate the 10 values for Math.sin(i) and Math.cos(i) and store them in an Array (basically a LUT - Look Up Table) as these are the heaviest math ops you're doing.
My final tip is that your code doesn't check if the point being drawn is very close to the last point that was drawn. I would recommend you do this, and only draw a point after the mouse has moved a minimum distance (e.g. 2 pixels). Otherwise you could get the mouse sitting still in one spot and your code is drawing circle upon circle on top of itself needlessly.
Try increasing the FPS in your document to atleast double what you currently have
Modify>Document...>Frame Rate
I dispatched an event for a bullet to spawn on the page. However the bullet should be located in the area where the page's child child should be. There is a Page One MovieClip, which has a child named player and the player's child is gun. So I'm trying to keep the location and rotation of the bullet the same as the player's gun. So I need to access Page One's child's child. The player and the turret are using instance names and not variables.
I tried this code, but the bullet spawns in the page but will not spawn itself on the turret's location. This event is located in the PageOne class.
function fire(e:Event)
{
var b:Bullet = new Bullet();
b.rotation = player.turret.rotation;
b.x = player.turret.x + player.turret.width * Math.cos(player.turret.rotation / 180 * Math.PI);
b.y = player.turret.y + player.turret.width * Math.sin(player.turret.rotation / 180 * Math.PI);
addChild(b);
}
You can access to the turret child. The problem is that you need to convert the coords inside the turret MovieClip to the coords inside the PageOne MovieClip:
var b: Bullet = new Bullet();
var turretpoint:Point = new Point(player.turret.width, 0);
var pagepoint: Point = this.globalToLocal(player.turret.localToGlobal(turretpoint));
b.rotation = (player.scaleX > 0) ? player.turret.rotation : 180 - player.turret.rotation;
b.x = pagepoint.x;
b.y = pagepoint.y;
addChild(b);
Help please write a function of the projectile bounce off the ground. How do I find the angle of the collision, and what should be the reflection angle or at least learn the point of collision?
package {
import flash.display.Sprite;
import flash.display.Bitmap;
import flash.display.BitmapData;
import flash.display.BlendMode;
import flash.geom.Point;
import flash.geom.Matrix;
import flash.events.Event;
import flash.events.MouseEvent;
public class worms extends Sprite {
public var terrain_bmpd=new BitmapData(550,200,true,0xFF00FF00);//This is the Bitmap of the terrain
public var terrain_bmp=new Bitmap(terrain_bmpd);//and this the BitmapData
public var character=new Sprite();//The character will work as a worm
public var hole=new Sprite();//That's the hole we need
public var hole_matrix:Matrix;//The hole_matrix is used to set the position of the hole
public var left_foot:Point;
public var right_foot:Point;//These are the feet of the character. We will use it to check collisions
public function worms() {
draw_objects();//This function draws the character, the terrain and the hole.
stage.addEventListener(Event.ENTER_FRAME,fall);
}
public function fall(e:Event) {
/*This function will move down the character if there isn't a collision
between the terrain and the "feet" of the character*/
for (var i:int=0; i<10; i++) {//We want to check every pixel if there's acollision, so we won't move the character 10 pixels all at once
left_foot=new Point(character.x-5,character.y+10);
right_foot=new Point(character.x+5,character.y+10);
if (!(terrain_bmpd.hitTest(new
Point(terrain_bmp.x,terrain_bmp.y),0x01,left_foot))&&!(terrain_bmpd.hitTest(new Point(terrain_bmp.x,terrain_bmp.y),0x01,right_foot))) {
character.y++;//If there aren't any collisions, make the character fall one pixel
}
}
}
public function draw_objects() {
terrain_bmp.y=200;//The terrain shouldn't be at the top of the stage!
stage.addChild(terrain_bmp);//We can make the terrain visible
character.graphics.beginFill(0x0000FF);//Let's draw the character. It will be a blue rectangle.
character.graphics.drawRect(-5,-10,10,20);
character.x=250;
stage.addChild(character);
hole.graphics.beginFill(0x000000);//Now we draw the hole. It doesn't matter the colour.
hole.graphics.drawCircle(0,0,30);
}
}
}
There's several parts to this, and it seems you don't really know where to begin.
Like the others have mentioned, your object (projectile, character, etc) movement should be represented by a vector, ie x and y velocity. (A Point can represent a vector.)
Next, to detect angle of collision on pixel-based terrain like you have, you can do a series of point (pixel) hit tests in a radius around the object. This will give you a collection of hit points, which you define as vectors from the center of the object. Average the vectors and you have your collision angle.
Here's a function I've used to do this:
/**
* Test for a hit against a shape based on a point and radius,
* returns the angle of the hit or NaN if no hit.
* Like hitTestPoint, xPos and yPos must be in stage coordinates.
*/
function hitTestAngle(shape:Sprite, xPos:Number, yPos:Number, radius:Number, samples:uint = 90):Number {
const PI2:Number = Math.PI * 2, SAMPLE:Number = 1 / samples;
var dx:Number, dy:Number, a:Number, tx:Number = 0, ty:Number = 0, hits:int = 0;
var i:int = samples;
while(i--){
a = PI2 * (i * SAMPLE);
dx = radius * Math.cos(a);
dy = radius * Math.sin(a);
if(shape.hitTestPoint(xPos + dx, yPos + dy, true)){
hits++;
tx += dx;
ty += dy;
}
}
if(!hits)
return NaN;
return Math.atan2(ty, tx) * (180 / Math.PI);
}
This uses hitTestPoint() but since your terrain is BitmapData you could just use getPixel32() and check the alpha value.
You could also use Collision Detection Kit, which uses a similar approach under the hood, with a bunch of extra features.
Once you have the angle of collision, you can define a perpendicular vector as the collision surface to reflect the projectile's vector.
That should get you started.
Flat, horizontal ground:
//Check next movementstep
if((vel_y + pos_y) > terrainBottom) {
vel_y = -vel_y*DampingFactor;
}
for the general case you need to transform vel_x, vel_y into the case shown above using trigonometric functions.
As in the previous answer, use vel_x and vel_y to represent the motion of your character in vector form. Use these values to increase your x and y co-ordinates at each iteration. In your example you are using vel_x = 0, vel_y = 1, because you are increasing the y-coordinate by 1 each time.
If a surface has an an angle A measured counter-clockwise from the horizontal then x_vel and y_vel after bouncing (relfecting) on the surface will be
x_vel.cos2A + y_vel.sin2A and x_vel.sin2A - y_vel.cos2A respectively. To see how this is derived see planetmath
This is for a perfectly elastic collision, ie no loss of speed on impact.
from my main class i call to create a sprite and add it to the stage
private function addSwatch(evt:MouseEvent):void
{
if (stage.getObjectsUnderPoint(mousePoint()).length == 0)
{
var swatchSide:Number = 100;
var newSwatch:Sprite = new Swatch(0 - swatchSide/2, 0 - swatchSide/2, swatchSide, swatchSide);
newSwatch.x = mouseX;
newSwatch.y = mouseY;
addChild(newSwatch);
}
}
i've added a swatch sprite to the stage which, when dragged, is contained within set boundaries.
this.startDrag(false, swatchBounds());
...
private function swatchBounds():Rectangle
{
var stageBounds = new Rectangle (
0 - defaultSwatchRect.x,
0 - defaultSwatchRect.y,
stage.stageWidth - defaultSwatchRect.width,
stage.stageHeight - defaultSwatchRect.height
);
return stageBounds;
}
if the square sprite is scaled, the following returned rectangle boundary works
private function swatchBounds():Rectangle
{
var stageBounds = new Rectangle (
0 - defaultSwatchRect.x * swatchObject.scaleX,
0 - defaultSwatchRect.y * swatchObject.scaleY,
stage.stageWidth - defaultSwatchRect.width * swatchObject.scaleX,
stage.stageHeight - defaultSwatchRect.height * swatchObject.scaleY
);
return stageBounds;
}
now i'm trying to include the square sprites rotation into the mix. math certainly isn't my forté, but i feel i'm on the write track. however, i just can't seem to wrap my head around it to get it right
private function swatchBounds():Rectangle
{
var stageBounds = new Rectangle (
0 - defaultSwatchRect.x * swatchObject.scaleX * Math.cos(defaultSwatchRect.x * swatchObject.rotation),
0 - defaultSwatchRect.y * swatchObject.scaleY * Math.sin(defaultSwatchRect.y * swatchObject.rotation),
stage.stageWidth - defaultSwatchRect.width * swatchObject.scaleX * Math.cos(defaultSwatchRect.width * swatchObject.rotation),
stage.stageHeight - defaultSwatchRect.height * swatchObject.scaleY * Math.sin(defaultSwatchRect.height * swatchObject.rotation)
);
return stageBounds;
}
My idea is that instead of using complicated trig, just get the bounding rect of swatchObject using swatchObject.getRect() and then create your stageBounds based on that. It should be more than good enough for your purposes.
If that is not what you want, I can help you figure out the math.
And sorry, I can't really give you a function until I figure out what defaultSwatchRect is - where its x and y is and what it's supposed to do.
Another thing you may want to keep in mind for the future: the Math functions (cos, sin) expect the angle in radians, whereas the .rotation property is in degrees, so you must convert before using.
I am making a Sim City like game. There are lots of tiles. When I first started. I was just using a tilesheet. I was copying the necessary pieaces from the tilesheet. on to a blank bitMapData. I then took the bitMapData and put it into a bitMap which I then put into a DisplayObject. It worked great!
tileSheet:BitMapData <----- data is already in
loop { loop through and tiled
bg:bitMapData= new bitMapData();
bg.copyPixel(tileSheet,rect,point);
}
canvas.BitMap(bg);
addChild(canvas);
Only problem was I needed to make my tiles interactive. I needed to highlight them and change colors and stuff. So I used the Sprite object. It works great but I can only have so many on the stage at once. or else it moves slow when I scroll. I need something Lighter then a sprite, but yet I can still turn into a object to make interactive. Anyone have any ideas ???
If you have a lot of tiles, that will impact performance because Flash needs to update the transformations of a lot of display objects (which internally means a lot of matrix calculations, and subsequent redraws of big areas of the screen.)
There is another way to achieve interactivity, if you find that you must use a single bitmap data for performance. Keep an "abstract" (i.e. not graphical) data model in memory, that stores your game state. Make sure that you are able to read from your store where a certain element is positioned in the game world. Then you can use a flat bitmap data to render the game world, because the individual positions are stored elsewhere.
When the user clicks the DisplayObject containing the bitmap data (a Sprite in which the bitmap is drawn using a bitmap fill, or that wraps a Bitmap), look in your model which of your game elements was hit by that click.
// myTileSprite is a Sprite with a bitmap fill
myTileSprite.addEventListener(MouseEvent.CLICK, handleWorldClick);
function handleWorldClick(ev : MouseEvent) : void
{
var i : int;
// Loop through all game element data models
for (i=0; i<myGameElements.length; i++) {
// Test the mouse position against the element model
if (myGameElements[i].hitTest(myTileSprite.mouseX, myTileSprite.mouseY)) {
trace('this was the element that was clicked: '+myGameElements[i].toString());
}
}
}
Here, whenever the player clicks the world graphics, the loop tries to find that element which was directly under the mouse position. You will need to implement a hitTest() method on all your game element data models, of course. Such a method simply checks the supplied world space position against the tile's area:
// GameElement.hitTest():
/**
* Tests a world position against the position and area of this game
* element tile. Returns a boolean indicating whether this tile was hit.
*/
public function hitTest(mouseX : Number, mouseY : Number) : void
{
var rect : Rectangle = new Rectangle(this.worldX, this.worldY, this.width, this.height);
if (mouseX > rect.left && mouseX < rect.right
&& mouseY > rect.top && mouseY < rect.top) {
return true;
}
else return false;
}
The GameElement class is not an display object, but has worldX and worldY properties indicating where it is located in the world. It's width and height properties define it's dimensions.
The trick from hereon is to make sure that the rendered bitmap and your model storage is synchronized, so that a tile's position on the bitmap really corresponds to it's worldX/worldY properties in the data model.
I am one step ahead of you. And that is a great idea. Its alot easier to keep a data representation of the world when the tiles are squared. I therefore can take my mouseX/tileWidth, and thats hw many columns I moved from left to right. same with the Y axis.
Not only that but coordinates start at top left corner.
But issue I have is that my tiles are Isometric. So instead of the X axis start off like...
012345678
0
1
2
3
4
5
6
7
8
My tiles are aligned like...
00
1 1
2 2
3 3
4 4
5 6
its a little sloppy. but the right side represents the y axis and the left represents the x axis. and the center origin is in the center of the screen. not on the top left. I am trying to figure out how to measure where my mouse is from the center and out on both sides. This sounds extremely difficult. I am not sure if its possible. The game is suppose to be like a sim city like game. The first sim city was squares not isometric. I dont think they went isometric until they started using 3d. I wonder if its possible to create a illusion of isometric on a square tile.
Ive been reading this great book on isometrics. They show to calculate tiles in 3d space. and even calculate your mouse in 3d space as well. here is the code. Its alot, but I hope someone else understands it more then I. The book was written by jobe makar on building multiplayer worlds. I wanted to share it because the code it is pretty simple as far as amount of code put into it. only 2 classes needed. I am not that good with trigonometry. so I cant really interpret how the math is getting the results. hopefully someone can explain that for me :D.
Y coordinates are not given because the width is = to height. The coordinates method is just a custom made Point class which holds x, y and z.
package com.gamebook.grid {
import com.gamebook.utils.geom.Coordinate;
import com.gamebook.utils.Isometric;
import flash.display.MovieClip;
import flash.events.MouseEvent;
/**
* ...
* #author Jobe Makar - jobe#electrotank.com
*/
public class Map extends MovieClip{
private var _grid:Array;
private var _iso:Isometric;
private var _tileWidthOnScreen:int;
private var _tileHeightOnScreen:int;
private var _tileWidth:Number;
private var _tileHeight:Number;
private var _cols:int;
private var _rows:int;
private var _lastTile:Tile;
public function Map() {
initialize();
}
private function initialize():void{
_iso = new Isometric();
//when mapped to the screen the tile makes a diamond of these dimensions
_tileWidthOnScreen = 64;
_tileHeightOnScreen = 32;
//figure out the width of the tile in 3D space
_tileWidth = _iso.mapToIsoWorld(64, 0).x;
//the tile is a square in 3D space so the height matches the width
_tileHeight = _tileWidth;
buildGrid();
addEventListener(MouseEvent.MOUSE_MOVE, mouseMoved);
}
private function mouseMoved(e:MouseEvent):void {
if (_lastTile != null) {
_lastTile.alpha = 1;
_lastTile = null;
}
var coord:Coordinate = _iso.mapToIsoWorld(mouseX, mouseY);
var col:int = Math.floor(coord.x / _tileWidth);
var row:int = Math.floor(Math.abs(coord.z / _tileHeight));
if (col < _cols && row < _rows) {
var tile:Tile = getTile(col, row);
tile.alpha = .5;
_lastTile = tile;
}
}
private function buildGrid():void{
_grid = [];
_cols = 10;
_rows = 10;
for (var i:int = 0; i < _cols;++i) {
_grid[i] = [];
for (var j:int = 0; j < _rows;++j) {
var t:Tile = new Tile();
var tx:Number = i * _tileWidth;
var tz:Number = -j * _tileHeight;
var coord:Coordinate = _iso.mapToScreen(tx, 0, tz);
t.x = coord.x;
t.y = coord.y;
_grid[i][j] = t;
addChild(t);
}
}
}
private function getTile(col:int, row:int):Tile {
return _grid[col][row];
}
}
}
Then we have the isometric class that calculates 3d space.
package com.gamebook.utils {
import com.gamebook.utils.geom.Coordinate;
/**
* #author Jobe Makar - jobe#electrotank.com
*/
public class Isometric {
//trigonometric values stored for later use
private var _sinTheta:Number;
private var _cosTheta:Number;
private var _sinAlpha:Number;
private var _cosAlpha:Number;
/**
* Isometric class contrustor.
* #param declination value. Defaults to the most common value, which is 30.
*/
public function Isometric() {
var theta:Number = 30;//even though the tiles are already isometric, you still have to put the degrees the tiles will be turned.
var alpha:Number = 45;//45 degrees on y axis, 30 dgrees on x axis
theta *= Math.PI/180; // then you translate to radians
alpha *= Math.PI/180;
_sinTheta = Math.sin(theta);
_cosTheta = Math.cos(theta);
_sinAlpha = Math.sin(alpha);
_cosAlpha = Math.cos(alpha);
}
/**
* Maps 3D coordinates to the 2D screen
* #param x coordinate
* #param y coordinate
* #param z coordinate
* #return Coordinate instance containig screen x and screen y
*/
public function mapToScreen(xpp:Number, ypp:Number, zpp:Number):Coordinate {
var yp:Number = ypp;
var xp:Number = xpp*_cosAlpha+zpp*_sinAlpha;
var zp:Number = zpp*_cosAlpha-xpp*_sinAlpha;
var x:Number = xp;
var y:Number = yp*_cosTheta-zp*_sinTheta;
return new Coordinate(x, y, 0);
}
/**
* Maps 2D screen coordinates into 3D coordinates. It is assumed that the target 3D y coordinate is 0.
* #param screen x coordinate
* #param screen y coordinate
* #return Coordinate instance containig 3D x, y, and z
*/
public function mapToIsoWorld(screenX:Number, screenY:Number):Coordinate {
var z:Number = (screenX/_cosAlpha-screenY/(_sinAlpha*_sinTheta))*(1/(_cosAlpha/_sinAlpha+_sinAlpha/_cosAlpha));
var x:Number = (1/_cosAlpha)*(screenX-z*_sinAlpha);
return new Coordinate(x, 0, z);
}
}
}