I'm having some trouble getting an object to follow a path that is drawn with a touch event.
The problem is more in the smoothness of which the object follows the path.
/* the ACTION_MOVE code */
Hashtable<String, Integer> ht = new Hashtable<String, Integer>();
for (int h = 0; h < historySize; h++) {
for (int p = 0; p < pointerCount; p++) {
int newX = (int) event.getHistoricalX(p, h);
int newY = (int) event.getHistoricalY(p, h);
ht.put("x", newX);
ht.put("y", newY);
droid.path.add(ht);
}
droid.p.lineTo(x, y);
}
/* There's a game loop that calls a move() method on this droid object. In move I read the path list
and see the next coordinate to move the object to. */
I grab the coordinates as the user drags their finger across the screen using the
historic methods so I don't miss any points.
The problem is the smoothness that the object moves along this path.
If you draw your path slow then the droid will move slowly across the screen
( because more x,y points are captured? )
But if you draw the line fast then the droid moves really fast.
I need the object to move at a consistent speed across the path.
I somehow need to regulate the spacing between the points added to the hashTable or the
sample rate at which points are read in so its consistent and the object looks smooth
following the path.
I've googled this one a good bit and i'm having some trouble finding anything.
Any shove in the right direction would be appreciated.
Thanks so much!
Here I showed how to move and rotate an image along any path. Build a smooth path from your points. Then you can specify any number of points to make nice animation.
Related
So, my problem is that I'm currently working on a path-finding technique in an open world with tiles of various sizes. The object needs to find an optimal path to a destination inside an infinite world (it generates on the fly), which is filled with tiles of various sizes (which are not located on a set grid - they can have any location and size - and neither have to be integers). (The object has access to the data of all the tiles via and ArrayList). Now some factors that make this problem more difficult:
The objects itself has a size and cannot move through tiles. Therefore, it is possible for a path to exist that is too narrow for the object to move through.
The target destination may itself be a moving object.
It is possible for there to be dozens of such objects at the same time - so it is necessary for the algorithm to either be light on the system or for the path to be calculated in a few separate ticks of the program.
I tried implementing solutions for maze-solving techniques, but the main problem is the in most mazes, the tiles can only have very specific coordinates (such as whole numbers) and are always the same size.
I also tried rendering the scene as a giant conventional maze where tiles are actually pixels of tiles (so if i have a 20x40 tile it becomes a 20x40 block of 1x1 tiles), but ran into performance issues and the still didn't solve the issue with a path potentially being to narrow for the object to fit through.
EDIT:
Terribly sorry for my poor wording before, that happens when I'm trying to rush to a solution without fully understanding the question. So what I'm using the algorithm for at the moment is for NPC enemies to find their way to the player around obstacles. Here is an example of a scene:
The black circle with an arrow is the player, the black bush-like blobs are the NPC enemies. So this my my current algorithm I'm using for the enemy AI:
void move() { //part of the Enemy class, this function is called once each tick for every enemy
PVector velocity = new PVector(speed*game.dt, 0); //speed is a pre-set float denoting the enemy's speed, game.dt is deltatim
velocity.rotate(atan2(game.player.location.y-location.y, game.player.location.x-location.x)); //game.player.location is a PVector of the player's position, location is a PVector of this enemy's position
boolean init_collision = getTileCollision(); //getTileCollision is a boolean of whether this enemy is colliding with any tile
location.add(velocity);
boolean collision = getTileCollision();
if (!init_collision && collision) { //if the enemy happens to spawn inside a tile, let is move out of it before checking for collision
location.sub(velocity);
if (desired_heading != -1) { //desired heading is the angle, in radians, of which 90-degree angle the enemy wants to move in, by default set to -1 (see my descrition of this algorithm below)
velocity = new PVector(speed*game.dt, 0);
velocity.rotate(desired_heading);
location.add(velocity);
if (getTileCollision()) {
location.sub(velocity);
velocity = new PVector(speed*game.dt, 0);
velocity.rotate(current_heading); //current heading the an angle, in radians, of which 90-degree angle the enemy is currently moving in. set to -1 by default but can not equal -1 if desired_heading is not -1
location.add(velocity);
if (getTileCollision()) {
location.sub(velocity);
desired_heading = -1;
current_heading = -1;
}
} else {
desired_heading = -1;
current_heading = -1;
}
} else {
float original_heading = velocity.heading();
desired_heading = radians(round(degrees(velocity.heading())/90.0)*90.0); //round to the nearest 90 degrees
velocity = new PVector(speed*game.dt, 0);
velocity.rotate(desired_heading);
location.add(velocity);
if (getTileCollision()) {
location.sub(velocity);
}
float turn = radians(90);
while (true) { //if it cant move, try rotating 90 degrees and moving
velocity.rotate(turn);
location.add(velocity);
if (!getTileCollision() && abs(round(degrees(current_heading)) - round(degrees(velocity.heading()))) != 180) {
current_heading = velocity.heading();
break;
} else {
location.sub(velocity);
}
}
}
} else {
desired_heading = -1;
current_heading = -1;
}
}
So what my terrible code hopes to accomplish is the the enemy first tries to move directly at the player. If it encounters an obstacle, it will round its angle to the nearest 90 degrees, set desired_heading to this and try to move through. If it cant, it will rotate another 90 degrees and so forth, always keeping the original rounded angle in mind.
This doesn't work remotely well as first of all, rotating 90 degrees has a 50% chance to go in the exact wrong diretion, so I tried adding
if (abs(original_heading - velocity.heading()+turn) < abs(original_heading - velocity.heading()-turn)) {
turn = radians(-90);
}
right before the while (true) but that broke the algorithm completely (sometimes the enemy will freeze in deep thought and not move ever again).
What am I doing terribly wrong? Should I try a different algorithm or does this one have potential?
I hope this is a better question now...
So I'm creating a game using Javax.swing library for my uni coursework.
I have created a window and I have successfully written code to procedurally generate a game map.
However, I am unable to change the focus of the map. What I mean is that the map is always stuck in one corner of the screen. (IE: Location is set to 0,0, hence the Graphics g (the map) is put in that location going outwards.)
I would like to be able to move the "camera" so that different areas of the map can be viewed by the player.
Bellow I have pasted my method that draws the map onto the screen. Could anyone tell me what I could do to have the camera move at runtime. AKA: to shift the map left or right.
I thought of having a Graphics object that will hold the map, and then I'd only draw a subImage of that Graphics object, but considering how the map will be redrawn every frame (For animation purposes) that just means that I'll have even more graphics to redraw.
The map is 6,400 * 6,400 Pixels
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
try {
for(int x = 0; x < OverworldMap.MAP_X_SIZE; x++){
for(int y = 0; y < OverworldMap.MAP_Y_SIZE; y++){
for(int layer = 0; layer < OverworldMap.MAP_LAYER_SIZE; layer++) {
g.drawImage(OverworldMap.getTileAt(x, y, layer).getSprite(), x * SPRITE_SIZE, y * SPRITE_SIZE, null);
}
}
}
} catch (Exception e) {
LauncherClass.printErrorLog(e);
}
}
The best / easiest way to solve this is to put a JScrollPane around your JPanel, and make the JPanel the size of your image. You don't need to worry about only repainting the right part of your image - Java is pretty smart about only drawing the parts that are on screen. Note that you can show or hide the ScrollBars, but if you hide them you need to add logic to activate scrolling through some other mechanism
You cannot store a Graphics object and use it later. It is only valid for the duration of the paint method to which it is passed.
You can, however, simply offset your painting:
Image sprite = OverworldMap.getTileAt(x, y, layer).getSprite();
g.drawImage(sprite, x * SPRITE_SIZE - playerX, y * SPRITE_SIZE - playerY, this);
(Notice that the last argument to drawImage should be this.)
I have an ellipse:
Ellipse2D e2D = new Ellipse2D.Float(startPoint.x, startPoint.y, x - startPoint.x, y - startPoint.y);
And what I need is to get coordinates of all points that form circumference.
ArrayList<Point> oneDraw = new ArrayList<>();
for (int i = startX; i < borderX; i++)
for (int j = startY; j < borderY; j++)
if (e2D.contains(new Point(i, j)))
oneDraw.add(new Point(i, j));
By doing so, I put all coordinates that are inside my circle to the list, but I don't need this.
Thank you for the answer and spent time.
Create an ellipse that is a little larger than the target ellipse.
Create an ellipse that is a little smaller than the target ellipse.
Subtract the 2nd ellipse from the first. This will form an elliptical ring.
Do the current 'contains' code with the elliptical ring.
Your approach would add all pixels in the box which are inside the ellipse to the list, i.e. you'd get the area of the ellipse rather than its circumference. I'd say it would be better to look for the correct formula and solve it for discrete x/y pairs.
Or yet better apply one of the algorithms for drawing ellipses that can be found on the net, e.g. this one: http://www.mathopenref.com/coordcirclealgorithm.html
Then get the pixels that have been drawn (if still needed).
Edit: if you have a look at the source code of Ellipse2D you can either get an an idea of how to implement your own algorithm or you could just use getPathIterator() with a uniform transform and then "rasterize" the path elements into your list.
So I am making a tetris game and one of the problems I am running into is piece rotation. I know I can just hard code it but thats not the right way to do it. The way the system works is I have a 2d array of an object 'Tile' the 'Tile' object has x, y coords, boolean isActive, and color. The boolean isActive basically tells the computer which tiles are actually being used (Since tetris shapes are not perfect quadrilaterals).
Here is how I would make a shape in my system:
public static Tile[][] shapeJ() {
Tile[][] tile = new Tile[3][2];
for (int x = 0; x < 3; x++) {
for (int y = 0; y < 2; y++) {
tile[x][y] = new Tile(false, Color.blue);
}
}
tile[0][0].setActive(true);
tile[0][0].setX(0);
tile[0][0].setY(0);
tile[1][0].setActive(true);
tile[1][0].setX(50);
tile[1][0].setY(0);
tile[2][0].setActive(true);
tile[2][0].setX(100);
tile[2][0].setY(0);
tile[2][1].setActive(true);
tile[2][1].setX(100);
tile[2][1].setY(50);
return tile;
}
Now I need to rotate this object, I do not know how to do that without hard coding the positions. There has to be an algorithm for it. Can anyone offer some help?
A good way that I used when writing a tetris clone is to use rotational matrices:
http://en.wikipedia.org/wiki/Rotation_matrix
So the coordinates (x',y') of the point (x,y) after rotation are:
x' = x*cos(theta) - y*sin(theta);
y' = x*sin(theta) + y*cos(theta);
Where theta is the angle of rotation(+-90 degrees or +-PI/2 radians for the java functions that I know)
In this case the blocks are rotated around the origin (0, 0) so you either have to have the coordinates of the block in special "block space" that then gets transposed onto "field space" or you take away the offset of the block so that it is centered at the origin every iteration.
I hope that helps, I am happy to answer specific questions in the comments.
Im trying to get a rectangle to move from a fixed location, to a click point in my game. I have it working to the point that im getting good coordinates from the e.getX and e.getY methods in the mouse listener class. I also have the rectangle moving in straight lines to the side or up and down by increasing and decreasing the positionX and Y values but i need a way to move it to any point that i click on, basically i need to set the change in x and y. The way i was thinking is to compute the rise and run of the line from the click points and the start point and then set the x and y values to the rise and run. If i do it this way, i need a way to decrease the rise and run values down to their lowest terms so it moves fluidly. Or if there is a way im not thinking of that you can offer any guidence that would be helpfull.
How are you drawing it at the moment? Below is a method I used to shoot bullets in a little game that I made/really should finish sometime.
This is by no means all the code you will need, and in some places there are better ways to do things (which I'm sure people will start to tell me in the comments section after :) ) but it should give you a basis to work from.
The one thing missing from this is regulating the speed at which it repaints (fps), sorry but I can't remember the simple way to do this right now (need to get back to my actual job!) Hope it helps.
The barebones of it will be something like this:
//these set out the current position of your rectangle
double recX, reYy, recH, recW;
//this gives something to manage speed
int speed;
public void paintComponent(Graphics g) {
g.drawRectangle(recX,rexY,recH,recW);
}
//here we work out the movement
public void clickedScreen(double x, double y){
double newX = x;
double newY = y;
//calculate the speed to move at
vX = newX - recX;
vY = newY - recY;
//get the distance
length = Math.sqrt((v1*v1)+(v2*v2));
//make it a unit vector
v1 = v1/length;
v2 = v2/length;
}
public moveRec(){
recX = recX+(v1*speed);
recY = recY+(v2*speed);
}
while(true) {
moveRec();
repaint();
}