Develop Reference

How to translate a rectangle to the previous mouse coordinates in processing

I'm brand new to java and I'm making a snake game. My next step is to add a rectangle to the snake whenever it eats food. My current thinking is, I want to add an identical rectangle that's translated to the previous position of (mouseX, mouseY). At least, translated a distance of one rectangle from the previous one, but oriented where the mouse previously was, to "follow" behind the piece in front of it. I'm not sure how to go about doing that, but here is my code thus far.
//snake
void snake() {
rect(mouseX, mouseY, 10, 10);
}
class Snake {
//variables
int len;
int wid;
int xcord;
int ycord;
//constructor
Snake(int x,int y, int len, int wid) {
this.len = len;
this.wid = wid;
this.xcord = x;
this.ycord = y;
rect(xcord, ycord, wid, len);
}
//clear screen
void update() {
background(255);
rectMode(CENTER);
rect(mouseX, mouseY, wid, len);
}
}
class Food {
//variables
int xcord;
int ycord;
int wid;
int len;
//constructor
Food() {
this.xcord = int(random(width - 5));
this.ycord = int(random(height - 5));
this.wid = 10;
this.len = 10;
rect(xcord, ycord, wid, len);
}
//update food position
void update() {
if( (mouseX > xcord) && (mouseX < xcord + wid) &&
(mouseY > ycord) && (mouseY < ycord + len)) {
xcord = int(random(width - 5));
ycord = int(random(height - 5));
//lengthen snake
}
}
//display food
void displayFood() {
rect(xcord, ycord, 10, 10);
}
}
Snake s;
Food f;
void setup() {
background(255);
s = new Snake(mouseX, mouseY, 10, 10);
f = new Food();
}
void draw() {
s.update();
f.update();
f.displayFood();
}

You make 2 variables
float pMouseX = mouseX;
float pMouseY = mouseY;
Then, in draw, after updating the snake, you update those variables:
s.update
pMouseX = mouseX;
pMouseX = mouseY;
For having more than 2 rectangles, instead of single variables, consider using an ArrayList of arrays.
An Array is basically a way to store multiple variables in one variable.
An ArrayList is similar, but it doesn't have a set size. This means that you can keep adding elements to ArrayLists, which is something you can't do with Arrays.
You can declare such an ArrayList like this:
ArrayList<float[]> arrayList = new ArrayList<float[]>(); //each element of the ArrayList is an array, which contains an x and y position
To get the x and y coordinates of any rectangle, use arrayList.get(indexOfTheRectangle)[0] //use 1 instead of 0 for the y coordinate
and update them like this:
for (int i = arrayList.length - i; i > 0; i++) { //you need to go through the array backwards, because otherwise, for each element, you end up changing the value it is supposed to get, which results in all elements having the same value.
arrayList[i] = arrayList[i - 1];
}
arrayList[0] = new float[]{mouseX, mouseY}

How to Get an Objects X position in processing

I am trying to make Space Invaders in Processing. I am currently working on getting the enemy to move correctly. I have got them to be drawn in the right spot but I haven't gotten them to be moved correctly. Here is my code:
PImage mainPlayer;
PImage enemyPlayer;
float Xspeed = 60;
float Yspeed = 60;
float X;
float Y;
Enemy EnemyPlayer = new Enemy("EnemyPlayerSpaceInvaders.png", 10, 10, 6);
void setup() {
size(1400, 800);
//enemyPlayer = loadImage("EnemyPlayerSpaceInvaders.png");
mainPlayer = loadImage("MainPlayerSpaceInvaders.png");
}
void draw() {
background(0);
Enemy[] enemyPlayer = new Enemy[60];
for (int i = 0; i < 5; i += 1) {
for (int j = 0; j < 11; j += 1) {
enemyPlayer[j *i] = new Enemy("EnemyPlayerSpaceInvaders.png", 50 + j * 100, 5 + 75 * i, 6);
}
}
for (int i = 0; i < 5; i += 1) {
for (int j = 0; j < 11; j += 1) {
if(enemyPlayer[j * i].alive){
enemyPlayer[j * i].Draw();
}
enemyPlayer[j *i].moveAndDraw(6);
}
}
}
class Enemy {
boolean alive = true;
float x;
float y;
float speed;
String playerTexFile;
PImage playerTex;
Enemy(String PlayerTexFile, float X, float Y, float Speed){
x = X;
y = Y;
speed = Speed;
playerTexFile = PlayerTexFile;
}
void Draw(){
playerTex = loadImage(playerTexFile);
image(playerTex, x, y);
}
void moveAndDraw(float Speed){
playerTex = loadImage(playerTexFile);
if(alive){
x += Speed;
if (x >= 1300) {
x = 100;
y += 50;
}
}
}
}
Here is my result:
The Draw function works but what you're seeing that is messing it up is the moveAndDraw() function.
And the enemy drawings aren't moving. I have made this before with c++ SFML but in that there is a very basic getPosition function. The reason I want to get position is that right now I'm having to use inaccurate numbers as the X and Y position and for the enemy to move correctly I need to know exactly what it's position is. I have checked multiple pages on processing.org but none of them helped. I haven't found any getPosition void and all the ones I've seen other people using a void to do this I just haven't been able to get it to work. If there is some code that could get me this to work or just some function I've looked over and even a website page I could look at I'd be open to it. Please tell me anything I can do to get this working.

The issue is that you recreate the enemies in every frame at it's initial position:
void draw() {
background(0);
Enemy[] enemyPlayer = new Enemy[60];
for (int i = 0; i < 5; i += 1) {
for (int j = 0; j < 11; j += 1) {
enemyPlayer[j *i] = new Enemy("EnemyPlayerSpaceInvaders.png", 50 + j * 100, 5 + 75 * i, 6);
}
}
// [...]
}
You've to:
Create a global array of enemies Enemy[] enemyPlayer (and delete PImage enemyPlayer).
Create and initialize the enemies in setup.
Use and move the existing enemies in draw:
Further note, that your loops doesn't do what you expect it to do. Create the enemies in 2 nested loops. If i runs from o to 6 and j from 0 to 10, the the index of an enemy is i*10 + j.
The enemies can be moved in a single loop from 0 to enemyPlayer.length.
//PImage enemyPlayer; <--- DELETE
// global array of enemies
Enemy[] enemyPlayer = new Enemy[60];
// [...]
void setup() {
size(1400, 800);
mainPlayer = loadImage("MainPlayerSpaceInvaders.png");
// create enemies
for (int i = 0; i < 6; i += 1) {
for (int j = 0; j < 10; j += 1) {
enemyPlayer[i*10 + j] = new Enemy("rocket64.png", 50 + j * 100, 5 + 75 * i, 6);
}
}
}
void draw() {
background(0);
// move enemies
for(int i = 0; i < enemyPlayer.length; ++i ) {
if(enemyPlayer[i].alive){
enemyPlayer[i].Draw();
}
enemyPlayer[i].moveAndDraw(6);
}
}

Writing a Raytracer, and cant get the image to be centred properly?

I'm writing a Raytracer in Java, I've gotten to the point where I can create objects, rays, test for intersections and then colour pixels. I've also got some basic anti aliasing done. My problem is that if a create a sphere, which should be in the centre of the world (i.e 0.0, 0.0, 0.0) and then draw the image, I end up with a picture like this.
When the red circle should be in the middle of the image.
Main method
public static void main(String[] args) {
System.out.println("Rendering...");
long start = System.nanoTime();
// Setting up the size of the image to be rendered
world = new World(1920, 1080, 1.0);
image = new Image("image.png");
sampler = new SimpleSampler(4);
projector = new OrthographicProjector();
// Main loop of program, goes through each pixel in image and assigns a colour value
for (int y = 0; y < world.viewPlane.height; y++) {
for (int x = 0; x < world.viewPlane.width; x++) {
// Render pixel colour
trace(x, y);
}
}
image.saveImage("PNG");
long end = System.nanoTime();
System.out.print("Loop Time = " + ((end - start)/1000000000.0f));
}
Trace method
public static void trace(int x, int y) {
Colour colour = new Colour();
//int colour = RayTracer.world.backgroundColour.toInteger();
for (int col = 0; col < sampler.samples; col++) {
for (int row = 0; row < sampler.samples; row++) {
Point2D point = sampler.sample(row, col, x, y);
Ray ray = projector.createRay(point);
double min = Double.MAX_VALUE;
Colour tempColour = new Colour();
for (int i = 0; i < world.worldObjects.size(); i++) {
double temp = world.worldObjects.get(i).intersect(ray);
if (temp != 0 && temp < min) {
min = temp;
tempColour = world.worldObjects.get(i).colour;
}
}
colour.add(tempColour);
}
}
colour.divide(sampler.samples*sampler.samples);
image.buffer.setRGB(x, y, colour.toInteger());
}
World.java
public class World {
public ViewPlane viewPlane;
public ArrayList<Renderable> worldObjects;
public Colour backgroundColour;
public World(int width, int height, double size) {
viewPlane = new ViewPlane(width, height, size);
backgroundColour = new Colour(0.0f, 0.0f, 0.0f);
worldObjects = new ArrayList<Renderable>();
worldObjects.add(new Sphere(new Point3D(0.0, 0.0, 0.0), 50, new Colour(1.0f, 0.0f, 0.0f)));
//worldObjects.add(new Sphere(new Point3D(-150.0, 0.0, 0.0), 50, new Colour(1.0f, 0.0f, 0.0f)));
//worldObjects.add(new Sphere(new Point3D(0.0, -540.0, 0.0), 50, new Colour(0.0f, 1.0f, 0.0f)));
}
}
SimpleSampler.java
public class SimpleSampler extends Sampler {
public SimpleSampler(int samples) {
this.samples = samples;
}
public Point2D sample(int row, int col, int x, int y) {
Point2D point = new Point2D(
x - RayTracer.world.viewPlane.width / 2 + (col + 0.5) / samples,
y - RayTracer.world.viewPlane.width / 2 + (row + 0.5) / samples);
return point;
}
}
OrthographicProjector.java
public class OrthographicProjector extends Projector{
public Ray createRay(Point2D point) {
Ray ray = new Ray();
ray.origin = new Point3D(
RayTracer.world.viewPlane.size * point.x,
RayTracer.world.viewPlane.size * point.y,
100);
ray.direction = new Vector3D(0.0, 0.0, -1.0);
return ray;
}
}
I have a feeling that somewhere along the way I've mixed an x with a y and this has rotated the image, but I haven't been able to track down the problem. If you would like to see any more of my code I would be happy to show it.

In SimpleSampler.java:
Point2D point = new Point2D(
x - RayTracer.world.viewPlane.width / 2 + (col + 0.5) / samples,
y - RayTracer.world.viewPlane.width / 2 + (row + 0.5) / samples);
You use width for both coordinates. Maybe you should use width and height.

Tile change color on mouse hover - prevent selecting more than one tile at once

I am creating a battle ship game, where each round the player can select 4 ship routes by selecting the 4 closest tiles to him, with a mouse.
Now in the following gif, you can see if I will hover on the very edge of a tile, it will select two tiles at once, or even 4 at once if you're holding your mouse in middle of 4 tiles:
(source: gyazo.com)
This should not really be happening in the game, how can I prevent that?
This is the updating code:
/**
*
* #param x mouse X
* #param y mouse Y
*/
public void checkHover(int x, int y) {
for (int i = 0; i < tiles[0].length; i++) {
for (int j = 0; j < tiles[1].length; j++) {
// get coordinates from tile
int x1 = i * (sprite.getWidth() - 1);
int y1 = j * (sprite.getHeight() - 1);
// If we have screen translate, we can cancel it for
// this situation
int realX = x - this.translate.getX();
int realY = y - this.translate.getY();
// checking if mouse inside tile
if (realX >= x1 && realX <= x1 + sprite.getWidth() &&
realY >= y1 && realY <= y1 + sprite.getHeight()) {
// set tile to hovered sprite
this.tiles[i][j].setHover(true);
}
else {
// cancel hovered sprite
this.tiles[i][j].setHover(false);
}
}
}
}
How can I prevent that?

Instead of the two loops I would calculate the index of the 2d array based off the x and y position of the mouse, by dividing the x and y position by how much space there is from one tile to the next (which looks to be the tile width plus 1, the empty border). This will cause border hovers to favor a certain side, but it looks like you don't want to select two tiles anyways.
Once you have the index of the tile, switch the highlight on, and keep a reference to it with an instance variable like lastHighlightedTile, but before you do that, also call lastHighlightedTile.setHover(false);.
If the index of the tile is invalid, as if the mouse is out of the tile area, don't access the array and still call lastHighlightedTile.setHover(false);.
This should fix highlighting multiple tiles, and will also allow you to turn off the previous highlight (the solution of breaking out of the current loop might not turn off the previous highlight).

Assuming width of sprite is equal to 50, I see that first title has x1 to x2 coordinate (0 - 50), second title has (49 - 100), third has (99 - 150)... Same for y dimension.
So when pointer is at (x) = (50), it hovers (x1 - x2) (0-50) and (49-100) titles.
Why are you subtracting 1 from sprite width / height?
try with this:
// get coordinates from tile
int x1 = i * (sprite.getWidth());
int y1 = j * (sprite.getHeight());
Edit: I wrote sample app, which shoved me solution:
public class App {
Tile[][] tiles;
Sprite sprite;
public static void main(String[] args) {
App app = new App();
app.init();
app.checkHover(50, 50);
app.printHovers();
}
private void init() {
sprite = new Sprite();
tiles = new Tile[10][10];
for (int i = 0; i < tiles[0].length; i++) {
for (int j = 0; j < tiles[1].length; j++) {
tiles[i][j] = new Tile();
}
}
}
public void checkHover(int x, int y) {
for (int i = 0; i < tiles[0].length; i++) {
for (int j = 0; j < tiles[i].length; j++) {
// get coordinates from tile
int x1 = i * (sprite.getWidth());
int y1 = j * (sprite.getHeight());
// If we have screen translate, we can cancel it for
// this situation
// int realX = x - this.translate.getX();
// int realY = y - this.translate.getY();
int realX = x;
int realY = y;
// checking if mouse inside tile
if (realX >= x1 && realX < x1 + sprite.getWidth()
&& realY >= y1 && realY < y1 + sprite.getHeight()) {
// set tile to hovered sprite
this.tiles[i][j].setHover(true);
} else {
// cancel hovered sprite
this.tiles[i][j].setHover(false);
}
}
}
}
public void printHovers() {
for (int i = 0; i < tiles[0].length; i++) {
for (int j = 0; j < tiles[i].length; j++) {
System.out.print((tiles[i][j].isHover() ? "Y" : "O") + " ");
}
System.out.println();
}
}
public class Sprite {
public int getWidth() {
return 50;
}
public int getHeight() {
return 50;
}
}
public class Tile {
private boolean hover;
public boolean isHover() {
return hover;
}
public void setHover(boolean hover) {
this.hover = hover;
}
}
}
It works fine for (49, 49), (49, 50), (50, 49) and (50, 50) coords.
So, first you have to remove -1 subtractions, and change <= test to <.

EDIT: Different solution:
Simply declare a boolean at the beginning of the method, and set only if that boolean is still false. Once you set the tile on, also set the boolean to true, which will prevent others from being set on.
public void checkHover(int x, int y) {
boolean hasTurnedOneOn = false;
for (int i = 0; i < tiles[0].length; i++) {
for (int j = 0; j < tiles[1].length; j++) {
// get coordinates from tile
int x1 = i * (sprite.getWidth() - 1);
int y1 = j * (sprite.getHeight() - 1);
// If we have screen translate, we can cancel it for
// this situation
int realX = x - this.translate.getX();
int realY = y - this.translate.getY();
// checking if mouse inside tile
if (realX >= x1 && realX <= x1 + sprite.getWidth() &&
realY >= y1 && realY <= y1 + sprite.getHeight() && !hasTurnedOneOn) {
// set tile to hovered sprite
this.tiles[i][j].setHover(true);
hasTurnedOneOn = true;
}
else {
// cancel hovered sprite
this.tiles[i][j].setHover(false);
}
}
}
}

How to delete object with a mouse click?

I made a simple FlowChat Editor that creates rectangles and triangles and connects them to each other and shows the way from up to down. I can move this elements on screen too.
I am now trying to create a button to delete the element which I clicked. There is problem that I can delete MyTriangle objects, but I can't delete MyRectangle objects. It deletes but not object which I clicked. I delete from first object to last.
Here is my code:
if (deleteObj) {
if (rectsList.size() != 0) {
for (int i = 0; i < rectsList.size(); i++) {
MyRect rect = (MyRect) rectsList.get(i);
if (e.getX() <= rect.c.x + 50 && e.getX() >= rect.c.x - 50
&& e.getY() <= rect.c.y + 15 && e.getY() >= rect.c.y - 15) {
rectsList.remove(rect);
System.out.println("This is REctangle DELETED\n");
}
}
}
if (triangleList.size() != 0) {
for (int j = 0; j < triangleList.size(); j++) {
MyTriangle trian = (MyTriangle) triangleList.get(j);
if (e.getX() <= trian.c.x + 20 && e.getX() >= trian.c.x - 20
&& e.getY() <= trian.c.y + 20 && e.getY() >= trian.c.y - 20) {
triangleList.remove(trian);
System.out.println("This is Triangle Deleted\n");
}
}
}
Edit Here MyRectangle and MyTriangle classes
public class MyRect extends Ellipse2D.Double {
Point c;
Point in;
Point out;
int posX;
int posY;
int width = 100;
int height = 30;
int count;
public MyRect(Point center, Point input, Point output,int counter) {
c = center;
in = input;
out = output;
count=counter;
}
void drawMe(Graphics g) {
// in.x=c.x+20;
int posX = c.x;
int posY = c.y;
int posInX = in.x;
int posInY = in.y;
int posOutX = out.x;
int posOutY = out.y;
g.setColor(Color.MAGENTA);
g.drawString(" S "+count ,posX-5, posY+5);
g.setColor(Color.black);
g.drawRect(posX-50, posY-15, width, height);
g.setColor(Color.green);
g.drawRect(posInX-3, posInY-9, 6, 6);
g.setColor(Color.blue);
g.drawRect(posOutX-3, posOutY+3, 6, 6);
}
}
public class MyTriangle {
Point c;
Point in ;
Point outYES ;
Point outNO ;
int posX;
int posY;
int count;
public MyTriangle(Point center,Point input,Point outputYES,Point outputNO,int counter) {
c = center;
in = input;
outYES = outputYES;
outNO = outputNO;
count=counter;
}
void drawMe(Graphics g) {
int posX = c.x;
int posY = c.y;
int posInX=in.x;
int posInY=in.y;
int posOutYESX=outYES.x;
int posOutYESY=outYES.y;
int posOutNOX=outNO.x;
int posOutNOY=outNO.y;
int[] xPoints = {posX - 50, posX, posX + 50, posX};
int[] yPoints = {posY, posY - 30, posY, posY + 30};
g.setColor(Color.MAGENTA);
g.drawString(" T "+count,posX-5, posY+5);
g.setColor(Color.black);
g.drawPolygon(xPoints, yPoints, 4);
// draw input
g.setColor(Color.green);
g.drawRect(posInX-3,posInY-9, 6, 6);
g.setColor(Color.blue);
g.drawRect(posOutYESX-9,posOutYESY-3 , 6, 6);
g.setColor(Color.red);
g.drawRect(posOutNOX-3,posOutNOY+3 , 6, 6);
}
}
Edit 2
Here my funcs to add object to list.Is there could be ant mistake?Because I am her ceratıng new object of that calss and I am addıng that object to rectlist or trianglelist..
public void initRect(Point c, Point in, Point out) {
sCounter++;
MyRect myrects = new MyRect(c, in, out, sCounter);
rectsList.add(myrects);
s_And_t_List.add(myrects);
objectCounter.add("S " + sCounter);
selectablePanel.repaint();
}
public void initTriangle(Point c, Point in, Point outYES, Point outNO) {
tCounter++;
MyTriangle mytriangles = new MyTriangle(c, in, outYES, outNO, tCounter);
triangleList.add(mytriangles);
s_And_t_List.add(mytriangles);
objectCounter.add("T " + tCounter);
selectablePanel.repaint();
}

It seems like your logic is wrong. In your Rectangle class why not make a method returning a boolean that tests if a given set of coordinates is contained in your object. For example:
public boolean contains(int x, int y){
if(x_starting_point <= x && x <= x_starting_point+width
&& y_starting_point <= y && y <= y_starting_point+height)
return true;
return false;
}