I've been banging my head up against a wall for the past couple of days trying to figure out how to properly extend CitrusEngine's Box2DPhysicsObjects to generate my custom objects. My goal is to generate this behavior:
example of desired behavior.
This is designed to simulate my hero dashing at a direction determined by using input while swinging his sword to attack. The sword "sleeps" until the attack state is activated.
I think I have a fundamental misunderstanding of how to properly use Box2D (especially joints). If someone could point me in the right direction I would be eternally grateful. I can't really provide my current code because it's become beyond broken.
An implementation such as the one above would have very poor performance and would likely tunnel in almost every situation. Therefore a solution is to add a sensor with a funnel shape and add a joint between this sensor and my hero. The implementation:
override protected function createShape():void{
var radius:Number = 4;
var vertices:Vector.<b2Vec2> = new Vector.<b2Vec2>();
vertices.push(new b2Vec2(0,0));
for (var i:int = 0; i < 7; i++) {
var angle:Number = i / 6.0 * .5* Math.PI;
vertices.push(
new b2Vec2( radius * Math.cos(angle),
radius * Math.sin(angle) ));
}
var sword_shape:b2PolygonShape = new b2PolygonShape();
sword_shape.SetAsVector(vertices,8);
_shape = sword_shape;
}
Related
Sorry if the title is ambiguous, I don't know how to really word what I'm trying to do.
So, anyway, I've created a basic zombie game where green squares follow you, you can die and kill the zombies.
The problem is, if there's a large crowd of the zombies, they all go into eachother and make one square, seeing as collision is too hard to do since they're moving along where they're pointing (pointing at the player), is there a way I can keep them spread out enough so they never go into eachother?
here's the code where I move the zombies:
for (var i2:int; i2 < ZombiesOnScreen.length; i2++ )
{
if (ZombiesOnScreen[i2].alive == true)
{
var dist_Y2:Number = player.y - ZombiesOnScreen[i2].y;
var dist_X2:Number = player.x - ZombiesOnScreen[i2].x;
var angle2:Number = Math.atan2(dist_Y2, dist_X2);
var degrees2:Number = angle2 * 180 / Math.PI;
ZombiesOnScreen[i2].rotation = degrees2;
var zomBAngle:Number = ZombiesOnScreen[i2].rotation * Math.PI / 180;
ZombiesOnScreen[i2].x = ZombiesOnScreen[i2].x + 1.6 * Math.cos(zomBAngle);
ZombiesOnScreen[i2].y = ZombiesOnScreen[i2].y + 1.6 * Math.sin(zomBAngle);
}
if (ZombiesOnScreen[i2].hitTestObject(player))
{
gameOver();
}
}
Also, sorry if this is literally just collision but just spaced out, I just want a way to stop them merging.
It may be beyond your current programming level but one common approach to this is on based the work of Craig Reynolds, outlined in his paper entitled "Flocks, herds and schools: A distributed behavioral model". He later released the C++ lib "openSteer." See his paper Steering Behaviors For Autonomous Characters for Java applet examples and a simplified explanation.
There have been many actionscript implementations of flocking behavior and ports of openSteer. Be careful though – you can't just copy and paste the code.
So, I'm trying to get a few movieclips to follow it's precursor and have the last one follow the mouse. The problem is I'm creating them from code instead of using the interface and, since I'm not an expert, I can't get them to work.
All I have in the library is a MovieClip(linkage:"LETRA") which contains a textField inside(instance name:"myTextField").
Here's what I have:
import flashx.textLayout.operations.MoveChildrenOperation;
import flash.display.MovieClip;
import flash.events.Event;
//this are the letters that will be following the mouse
var phrase:Array = ["H","a","c","e","r"," ","u","n"," ","p","u","e","n","t","e"];
//variable to spread them instead of creating them one of top of each other
var posXLetter:Number = 0;
//looping through my array
for (var i:Number = 0; i < phrase.length; i++)
{
//create an instance of the LETRA movieclip which contains a text field inside
var newLetter:MovieClip = new LETRA();
//assing a letter to that text field matching the position of the phrase array
newLetter.myTextField.text = phrase[i];
//assign X position to the letter I'm going to add
newLetter.x = posXLetter;
//add properties for storing the letter position
var distx:Number = 0;
var disty:Number = 0;
//add the listener and the function which will move each letter
newLetter.addEventListener(Event.ENTER_FRAME, moveLetter);
function moveLetter(e:Event){
distx = newLetter.x - mouseX;
disty = newLetter.y - mouseY;
newLetter.x -= distx / 10;
newLetter.y -= disty / 10;
}
//add each letter to the stage
stage.addChild(newLetter);
//increment the next letter's x position
posXLetter += 9;
}
With that code, only one letter is following the mouse (the "E") and the rest are staying where I added them using addChild and the posXLetter variable.
Also, I'm trying to get it to behave more like a trail, so if I move up, the letters will lag beneath me; if I move to the left, the letters will lag to my right but I think that with my current approach they will either A) move all together to the same spot or B) always hang to the left of the cursor.
Thanks for any possible help.
This is a kind of motion called Inverse Kinematics and it is a quite popular way to make rag dolls in games. It uses a design pattern called the Composite Pattern where one object adds another object as a child of its and then when it's update() function if called, it calls all of its (usually one) child's update() functions. The most common example of this is of a snake. The snake's head follows your mouse, and the rest of the snake's body pieces move with the snake, and it looks immensely realistic. This exact example is explained and build here although it does not include joint restrictions at all.
This example is in the middle of a book, and so may be hard to start reading, but if your somewhat familiar with design patterns and/or have some intermediate experience with programming, then i'm sure you can understand it. I advise that you, after reading and understanding the example, scratch what you have now because it is not very elegant coding. You may feel that this example uses too many classes, but trust me, its worth it as it allows you to very easily edit your code, if you decide to change it in the future, with no drawbacks.
Also, i know that this snake is not what you want, but if you understand the concept then you can apply it to your own specific needs.
I hope this helps.
I think it is a scoping issue. You might need to modify your handler
function moveLetter(e:Event){
trace(e.target); //check if this is the right movie clip
distx = e.target.x - mouseX;
disty = e.target.y - mouseY;
e.target.x -= distx / 10;
e.target.y -= disty / 10;
}
I'm building a 3D spinning carousel in AS3, basing it on Keith Peter's example.
I've got the carousel up and spinning and all is well, so far, but I can't for the life of me determine how to control it so that it spins to a specific element. I know it's just math, but right now, under tight deadline, I'm not grokking it. Any help appreciated.
I set it up with code below — there are currently 10 elements so each is spaced 36 degrees from the rest -- but ultimately there may be more or less elements, so it needs to work with a variable number. I want, for instance, to say 'spin to element 4' and it will spin there.
Thus I'm looking to set _container.rotationY, based on the specific element to which I want to go. So (pseudocode)
function gotoElement($element:int):void {
_container.rotationY = ?
}
I also need to figure out how to keep _container.rotationY between 0 and 360, but I suppose that's a simple modulus?
Any help GREATLY appreciated! Thanks!
private function createCarousel():void
{
_container.z = 0;
addChild(_container);
for (var i:int = 0; i<_numberOfImages; i++) {
var angle:Number = Math.PI * 2/_numberOfImages*i;
var item:JukeBoxAlbum = _images[i];
item.x = Math.cos(angle) * RADIUS;
item.z = Math.sin(angle) * RADIUS;
item.rotationY = (-360/_numberOfImages)*i + 270;
_items.push(item)
}
sortItems();
addEventListener(Event.ENTER_FRAME,loop,false,0,true);
stage.addEventListener(MouseEvent.CLICK,click,false,0,true);
}
First of all sorry for some english mistakes. Portuguese is my first language(I am from Brazil)
Im trying to make a space game from scratch in AS3 and the way to move the ship is like in the game Air Traffic Chief.
I succeed at some point. But when the ship is very fast it start to shake and its not very smooth and clean as I want.
Here is what i have done: http://megaswf.com/s/2437744
As the code is very big so I pasted in pastebin: pastebin.com/1YVZ23WX
I also wrote some english documentation.
This is my first game and my first post here. I really hope you guys can help me.
Thanks in advance.
Edit:
As the code is very big i will try to clarify here.
When the user MouseDown and MouseMove the ship every coordinate is passed to an array.
When the user MouseUP this array is passed to a function that fix the array.
For example: If the distance between two coordinates is greater than 5px, the function creates a coordinate in the middle of the two coordinates.
if I take this function off the problem seen to be solved. But if the user move the mouse very slow it still happens. It also creates a problem that i was trying to solve with that function. as the distance of the two coordinates are very big when the ship arrive in one coordinate most of the line path disappear.
I uploaded a version without the function that fixes the array. http://megaswf.com/s/2437775
I think there is 2 ways for solving this problem
1- Try to fix the noise in the array of coordinates 2- Take off the function that create an coordinate between two points and try to fix the problem of the line path disappear.
Here is the 2 important functions:
this function moves the ship
private function mover():void
{
if (caminhoCoords[0]!=null) // caminhoCoords is the array that contain the path
{
var angulo:Number = Math.atan2(this.y - caminhoCoords[0][1], this.x - caminhoCoords[0][0]);
this.rotation = angulo / (Math.PI / 180);
this.x = this.x - velocidade * (Math.cos(angulo));
this.y = this.y - velocidade * (Math.sin(angulo));
var testex:Number = Math.abs(this.x - caminhoCoords[0][0]); //test to see the distance between the ship and the position in the array
var testey:Number = Math.abs(this.y - caminhoCoords[0][1]);
if (testey<=velocidade+2 && testex<=velocidade+2) // if is velocidade+2 close then go to the next coordnate
{
caminhoCoords.shift();
}
}
}
This function draw the line:
private function desenhaCaminho():void //draw the black Path
{
if(caminhoCoords.length>=1)
{
caminho.graphics.clear();
caminho.graphics.lineStyle(1, 0x000000, 1,true);
caminho.graphics.moveTo(caminhoCoords[0][0],caminhoCoords[0][1]);
for (var i:int = 1; i < caminhoCoords.length; i++)
{
caminho.graphics.lineTo(caminhoCoords[i][0], caminhoCoords[i][1]);
}
}else
{
caminho.graphics.clear();
}
}
Every time the ship arrive in one coordinate is take that coordinate off the array and redraw the array.
Is there a better way of doing that?
I believe if you set your registration point of the plane to the centre and use .snapto(path), it will improve the action.
Judging from just the look of the stuttering, I would guess you need to smooth out the "line" a fair bit. It's probably picking up a lot of noise in the line, which is then translated into the rotation of the plane. Either smooth out the rotation/position of the plane, or the line itself.
I want to draw a 3D ball or sphere in HTML 5.0 canvas. I want to understand the Algorithm about how to draw a 3D sphere. Who can share this with me?
You will need to model a sphere, and have it be varying colors so that as it rotates you can see that it is not only a sphere, but being rendered.
Otherwise, a sphere in space, with not point of reference around it looks like a circle, if it is all one solid color.
To start with you will want to try drawing a circle with rectangles, as that is the main primitive you have.
Once you understand how to do that, or create a new primitive, such as a triangle, using the Path method, and create a circle, then you are ready to move it to 3D.
3D is just a trick, as you will take your model, probably generated by an equation, and then flatten it, as you determine which parts will be seen, and then display it.
But, you will want to change the color of the triangles based on how far they are from a source of light, as well as based on the angle of that part to the light source.
This is where you can start to do optimizations, as, if you do this pixel by pixel then you are raytracing. If you have larger blocks, and a point source of light, and the object is rotating but not moving around then you can recalculate how the color changes for each triangle, then it is just a matter of changing colors to simulate rotating.
The algorithm will depend on what simplifications you want to make, so as you gain experience come back and ask, showing what you have done so far.
Here is an example of doing it, and below I copied the 3D sphere part, but please look at the entire article.
function Sphere3D(radius) {
this.point = new Array();
this.color = "rgb(100,0,255)"
this.radius = (typeof(radius) == "undefined") ? 20.0 : radius;
this.radius = (typeof(radius) != "number") ? 20.0 : radius;
this.numberOfVertexes = 0;
// Loop from 0 to 360 degrees with a pitch of 10 degrees ...
for(alpha = 0; alpha <= 6.28; alpha += 0.17) {
p = this.point[this.numberOfVertexes] = new Point3D();
p.x = Math.cos(alpha) * this.radius;
p.y = 0;
p.z = Math.sin(alpha) * this.radius;
this.numberOfVertexes++;
}
// Loop from 0 to 90 degrees with a pitch of 10 degrees ...
// (direction = 1)
// Loop from 0 to 90 degrees with a pitch of 10 degrees ...
// (direction = -1)
for(var direction = 1; direction >= -1; direction -= 2) {
for(var beta = 0.17; beta < 1.445; beta += 0.17) {
var radius = Math.cos(beta) * this.radius;
var fixedY = Math.sin(beta) * this.radius * direction;
for(var alpha = 0; alpha < 6.28; alpha += 0.17) {
p = this.point[this.numberOfVertexes] = new Point3D();
p.x = Math.cos(alpha) * radius;
p.y = fixedY;
p.z = Math.sin(alpha) * radius;
this.numberOfVertexes++;
}
}
}
}
u can try with three.js library , which abstracts a lot of code from core webgl programming. Include three.js library in your html from three.js lib.
u can use canvas renderer for safari browser , webgl works for chrome
please find the JS FIDDLE FOR SPHERE
var camera, scene, material, mesh, geometry, renderer
function drawSphere() {
init();
animate();
}
function init() {
// camera
scene = new THREE.Scene()
camera = new THREE.PerspectiveCamera(50, window.innerWidth / innerHeight, 1, 1000);
camera.position.z = 300;
scene.add(camera);
// sphere object
var radius = 50,
segments = 10,
rings = 10;
geometry = new THREE.SphereGeometry(radius, segments, rings);
material = new THREE.MeshNormalMaterial({
color: 0x002288
});
mesh = new THREE.Mesh(geometry, material);
//scene
;
scene.add(mesh);
// renderer
renderer = new THREE.WebGLRenderer();
renderer.setSize(window.innerWidth, window.innerHeight);
document.body.appendChild(renderer.domElement);
}
function animate() {
requestAnimationFrame(animate);
render();
}
function render() {
mesh.rotation.x += .01;
mesh.rotation.y += .02;
renderer.render(scene, camera);
}
// fn callin
drawSphere();
Update: This code is quite old and limited. There are libraries for doing 3D spheres now: http://techslides.com/d3-globe-with-canvas-webgl-and-three-js/
Over ten years ago I wrote a Java applet to render a textured sphere by actually doing the math to work out where the surface of the sphere was in the scene (not using triangles).
I've rewritten it in JavaScript for canvas and I've got a demo rendering the earth as a sphere:
(source: haslers.info)
I get around 22 fps on my machine. Which is about as fast as the Java version it was based on renders at, if not a little faster!
Now it's a long time since I wrote the Java code - and it was quite obtuse - so I don't really remember exactly how it works, I've just ported it JavaScript. However this is from a slow version of the code and I'm not sure if the faster version was due to optimisations in the Java methods I used to manipulate pixels or from speedups in the math it does to work out which pixel to render from the texture. I was also corresponding at the time with someone who had a similar applet that was much faster than mine but again I don't know if any of the speed improvements they had would be possible in JavaScript as it may have relied on Java libraries. (I never saw their code so I don't know how they did it.)
So it may be possible to improve on the speed. But this works well as a proof of concept.
I'll have a go at converting my faster version some time to see if I can get any speed improvements into the JavaScript version.
Well, an image of a sphere will always have a circular shape on your screen, so the only thing that matters is the shading. This will be determined by where you place your light source.
As for algorithms, ray tracing is the simplest, but also the slowest by far — so you probably wouldn't want to use it to do anything very complicated in a <CANVAS> (especially given the lack of graphics acceleration available in that environment), but it might be fast enough if you just wanted to do a single sphere.