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draw images with random rotation java + processing

I'm drawing arrows using Java and I can draw them straight but now I need to have the arrows pointing in different directions.
In my current code, I draw a triangle and then a square.
Is there a way to group the two after they've been drawn and then rotate them at a random angle?
Right now I'm only able to rotate the triangle and square separately, causing some messy thing.
void setup() {
size(400, 400);
}
void draw() {
float r = random(24, 64);
background(255);
drawArrow(r);
//drawPlus(r);
saveFrame("dataArrow/plus####.png");
if (frameCount == 100) {
exit();
}
}
void drawArrow(float r){
float base = r * 2;
float xStart = random(1, width-base - 1);
float xEnd = xStart + base;
float k = 0.5 * base;
float y = random(k, width-k);
float middleBase = base/2 + xStart;
float rectSide = 0.5 * base;
float rectX1 = middleBase - rectSide/2;
float rectX2 = middleBase + rectSide/2;
fill(0);
triangle(xStart, y, xEnd, y, middleBase, y - k);
rect(rectX1, y, rectSide, rectSide);
}

not sure if this exactly what you mean but here is how to move things around
push and pop matrix allows you to organize things that should have the same translations
https://processing.org/reference/pushMatrix_.html
https://processing.org/reference/rotate_.html
https://processing.org/reference/translate_.html
basic example
pushMatrix();//start of new translation and rotation things
translate(xAmount,yAmount);//this moves the origin
rotate(angle);//this rotates around origin
//drawing around the point of rotation 0,0 here
//drawing...
popMatrix();//reset all translations and rotations to before

Making a moving circle disappear after being clicked on, Processing

I have written a program in which a UFO (in essence, a gray ellipse) appears from the center of the screen and flies to the edge. There is a laser that appears when the mouse is pressed, and disappears when the mouse is released. I want to make it so that the UFO disappears when the mouse clicks on it/the laser touches it.
I've made it as far as to make the UFO class and create variables that determine its movements and speed, and I was able to get the laser to appear directly on the cursor. I thought of making an 'if' statement to check if the cursor is within the radius (or diameter) of the UFO, and placing it inside of the for loop I created for the UFOs. However, I am not sure how to achieve the proper syntax to make it happen.
Note: You may need to wait a few seconds for the first circle to appear after you play the sketch.
UFO[] ufos = new UFO[3];
void setup() {
size(700, 700);
for (int j = 0; j < ufos.length; j++) {
ufos[j] = new UFO();
}
}
//UFO class
//Class setup ends on line 61
class UFO {
float a;
float b;
float c;
float sa;
float sb;
float d;
UFO() {
//declare float a/b/c value
a = random(-width/2, width/2);
b = random(-height/2, width/2);
c = random(width);
}
//UFO movement
void update() {
//float c will serve as a speed determinant of UFOs
c = c - 1;
if (c < 5) {
c = width;
}
}
//UFO setup
void show() {
//moving x/y coordinates of UFO
float sa = map(a / c, 0, 1, 0, width);
float sb = map(b / c, 0, 1, 0, height);
float d = map(c, 0, width, 50, 0);
//UFO drawing shapes
//ellipse is always sa (or sb) / c to allow UFO to appear
//as if it is moving through space
fill(200);
ellipse((sa / c), (sb / c), d + 5, d+5);
//Hides UFO way off the screen
//and replaces it with a black-filled ellipse until
//it forms into a full circle
//When radius d becomes 50, the UFO flies from the
//center of the screen to off of the screen
if (d < 50) {
fill(0);
ellipse(-5, -10, 90, 90);
sa = 10000;
sb = 10000;
}
}
}
void draw() {
//Background
background(0);
//Translated the screen so that the UFOs appear to fly from
//the center of the screen
translate(width/2, height/2);
//UFO draw loop, make UFO visible on screen
for (int j = 0; j < ufos.length; j++) {
ufos[j].update();
ufos[j].show();
//mouse-click laser
if (mousePressed == true) {
fill(200,0,0);
ellipse(mouseX - 352,mouseY - 347,50,50);
}
}
}

Like I said on the Happy Coding forum:
Basically, if your UFO is a series of circles, then you just need to use the dist() function to check whether the distance from the mouse to the center of the circle is less than the radius of the circle. If it is, then the mouse is inside the circle. Here's a small example:
float circleX = 50;
float circleY = 50;
float circleDiameter = 20;
boolean showCircle = true;
void draw(){
background(0);
if(showCircle){
ellipse(circleX, circleY, circleDiameter, circleDiameter);
}
}
void mousePressed(){
if(dist(mouseX, mouseY, circleX, circleY) < circleDiameter/2){
showCircle = false;
}
}
If your UFO is multiple circles, then you need to apply this logic to each circle. Please try something and post a small example like this one (not your whole sketch) if you get stuck. Good luck.

Libgdx intersection of polygons

I'm learning libgdx by adding some more features to the open source jumper game from Mario Zechner. I'm trying to make some platforms with an angle and run into the problem of collision detection of rotated rectangles.
I followed this solution and used Polygons along with my rectangle bounds.
For testing purposes I don't set an angle yet. I just want to verify that bob jumps correctly off the platforms. But for some reason this doesn't work. the bounds are either too far to the left, above the platform, or not there at all. Am I not setting the polygon correctly?
Would it be easier to use Box2d? I don't have any experience with that and I'm wondering if that's overkill for simple platforms.
public PlatformClient(int platformType, float x, float y) {
this.platformType = platformType;
float x1 = x - Platform.PLATFORM_WIDTH/2;
float y1 = y + Platform.PLATFORM_HEIGHT/2;
this.polyBounds = new Polygon(new float[]{x1, y1, x1+Platform.PLATFORM_WIDTH, y1, x1+Platform.PLATFORM_WIDTH, y1-Platform.PLATFORM_HEIGHT, x1, y1-Platform.PLATFORM_HEIGHT});
polyBounds.setPosition(x-Platform.PLATFORM_WIDTH/2, y-Platform.PLATFORM_HEIGHT/2);
}
class Platform {
public static final float PLATFORM_WIDTH = 2f;
public static final float PLATFORM_HEIGHT = 0.35f;
}
In Bob class update the polygon bounds when he moves:
public void update(float deltaTime) {
...
position.add(velocity.x * deltaTime, velocity.y * deltaTime);
bounds.x = position.x - BOB_WIDTH / 2;
bounds.y = position.y - BOB_HEIGHT / 2;
float newX = position.x - BOB_WIDTH / 2;
float newY = position.y - BOB_HEIGHT / 2;
polyBounds.setVertices(new float[]{
newX, newY,
newX+BOB_WIDTH, newY,
newX+BOB_WIDTH, newY-BOB_HEIGHT,
newX, newY-BOB_HEIGHT});
}
In World class:
private void checkPlatformCollisions () {
int len = platforms.size();
for (int i = 0; i < len; i++)
{
PlatformClient platform = platforms.get(i);
if (bob.position.y >= platform.position.y)
{
if(Intersector.overlapConvexPolygons(bob.polyBounds, platform.polyBounds))
{
System.out.println("it overlaps");
// jump off platform
}
}
}
}
EDIT
Thanks to the shape renderer, I was able to set the polygons correctly. I fixed some +,- issues in the code above. But the following code: Intersector.overlapConvexPolygons() still doesn't work (see image). He jumps before the polygons are making contact or he doesn't jump at all.
Any further ideas?
That's how I draw the polygon of Bob and the platforms that clearly overlap.
public void render() {
shapeRenderer.setProjectionMatrix(cam.combined);
shapeRenderer.begin(ShapeType.Line);
for(int i=0; i<world.platforms.size(); i++) {
shapeRenderer.setColor(1, 0, 0, 1);
shapeRenderer.polygon(world.platforms.get(i).polyBounds.getVertices());
shapeRenderer.polygon(world.bob.polyBounds.getVertices());
}
shapeRenderer.end();
}

ok, I solved it by removing
polyBounds.setPosition(x-Platform.PLATFORM_WIDTH/2, y-Platform.PLATFORM_HEIGHT/2);
from the constructor. Now the collision works correctly.

Java 2d game - Issues with delta time and collision

I'm trying to make a java 2d game, and it seems to work out fine in general. The only problem is, that I can't figure out how to place my "delta" time, to make the movements move the same on 30 FPS as on 1000 FPS.
This is my code for the Entity class:
import java.awt.Rectangle;
import map.Tile;
import graphics.Sprite;
public class Entity {
private String name;
private float positionx, positiony; // Current coordinate
private int targetx,targety; // Target coordinate
private double vx, vy; // Current vector
private double lx, ly; // Last vector
private float speed;
private Sprite sprite;
public Entity(String name, int x, int y, Sprite sprite){
this.name = name;
this.speed = 1f;
this.positionx = x;
this.positiony = y;
this.sprite = sprite;
main.Main.e.addEntity(this); // These kind of calls are ugly, and should be fixed.
}
public void remove(){
main.Main.e.removeEntity(this);
sprite.remove();
}
public void setVector(double vx, double vy){
this.vx = vx;
this.vy = vy;
}
public void update(long delta){
//Multiply modifier to make it act the same on 30 fps as 1000 fps.
vx = vx*delta;
vy = vy*delta;
// Calculate vector
double distance = Math.sqrt((vx * vx) + (vy * vy));
if(distance > 0){ // Have we reached the target yet?
vx = ((vx / distance));
vy = ((vy / distance));
}else{
vx = 0;
vy = 0;
}
//Check collision with objects:
Rectangle rx = new Rectangle((int) (vx+positionx), (int)positiony, 32, 32);
Rectangle ry = new Rectangle((int) positionx, (int)(vy+positiony), 32, 32);
for(Entity e : main.Main.e.getEntities()){
if(this != e){
if(isIntersecting(rx, e.getBounds())){
vx = 0; // Disallow x direction.
}
if(isIntersecting(ry, e.getBounds())){
vy = 0; // Disallow y direction.
}
}
}
//Check tiles:
for(Tile t : main.Main.m.getNeighbours(positionx,positiony)){
if(t.isBlocking()){
if(isIntersecting(rx, t.getBounds())){
vx = 0;
}
if(isIntersecting(ry, t.getBounds())){
vy = 0;
}
}
}
//Update the position:
positionx += vx*speed;
positiony += vy*speed;
//Animate:
animate(vx, vy);
}
public boolean isIntersecting(Rectangle r1, Rectangle r2){
return r1.intersects(r2);
}
public Rectangle getBounds(){
return new Rectangle((int) positionx,(int) positiony,32,32);
}
public void setMoveTo(int x, int y){
this.targetx = x;
this.targety = y;
}
//This function is used by the bots, and not on players (they are setting the vector and use update directly):
public void moveTo(long delta){
setVector((targetx-positionx),(targety-positiony));
update(delta);
}
public void animate(double dx, double dy){
sprite.setPosition((int)positionx, (int)positiony);
if(dx > 0){
sprite.setAnimation(0, 7, 100); // Walk right.
}else if(dx < 0){
sprite.setAnimation(1, 7, 100); // Walk left.
}else{
if(lx > 0){
sprite.setAnimation(2, 3, 200); // Stand right.
}else if(lx < 0){
sprite.setAnimation(3, 3, 200); // Stand left.
}
}
lx = dx;
ly = dy;
}
}
The two problems, that I always run into:
1# The game runs differently on 60FPS than on 500FPS.
2# The game runs the same on 60FPS as 500FPS, but my collision screws up, and I can't move closer than 15px from the other object. I think I need to implement something like: If I can't get 10px closer, then move it 10px closer, but I don't know how to implement it.
How can I implement it correctly? That would help a lot!

The easiest way would be to consider that if you want a constant displacement with a constant velocity you can scale all the deltas relative to the delta of 30 FPS like so:
So if you run at 60 FPS but want the same displacement as on 30FPS alpha would be (1/30)/(1/60) = 2
So
Remove vx = vx*delta;
vy = vy*delta;
and change your position update to
alpha = (1.0/30)*delta;
positionx += alpha*vx*speed;
positiony += alpha*vy*speed;
This is only a crude solution, let me know how it works, I will drop in later and update for a more correct solution (taking into account that delta is not always 1/FPS due to rendering and computation taking some time).
Edit: Variable delta will come later. But some optimizations:
You don't need to construct a rectangle in both Y and X for collisiondetection, try drawing two rectangles, if they intersect they do so on both axis. Just create a rectangle from vx + posx, vy+posy and check for intersection with this.
The above should half your collisionchecks. For further optimization consider using a QuadTree an implementation can be found here.
For the problem of "blocky" collision testing (where you stop X pixels from the blocking object). You can do the following, in pseudocode:
if(new position will make this colide)
while(this.position is more than one pixel away from blocking object)
keep moving one pixel
This will make you stop 1px from the target.

Java 2D Game - Checking if player touches another sprite

I have a game of a rocket landing game, where the player is the rocket and you must land it safely at the right speed on the landing pad. This was taken from www.gametutorial.net
Its actually for educational purposes and I recently added a still meteor in the game.
When the player hits the meteor (touches) the game is over.
if(...) {
playerRocket.crashed = true;
}
My problem is there I need to replace the "..." with the actual condition that "Has the rocket crashed into the meteor?"
Plus the following variables (coordinates, height and width) for use -
[All Integers]:
X and Y coordinates: playerRocket.x, playerRocket.y, meteor.x, meteor.y
Height and Width: playerRocket.rocketImgHeight, playerRocket.rocketImgWidth, meteor.meteorImgHeight, meteor.meteorImgWidth

For collision detection in 2D games, you can use rectangles. I'd use a base class called GObject and inherit all objects in the game from it.
public class GObject
{
private Rectangle bounds;
public float x, y, hspeed, vspeed;
private Image image;
public GObject(Image img, float startx, float starty)
{
image = img;
x = startx;
y = starty;
hspeed = vspeed = 0;
bounds = new Rectangle(x, y, img.getWidth(null), img.getHeight(null));
}
public Rectangle getBounds()
{
bounds.x = x;
bounds.y = y;
return bounds;
}
}
There's also other methods like update() and render() but I'm not showing them. So to check for collision between two objects use
public boolean checkCollision(GObject obj1, GObject obj2)
{
return obj1.getBounds().intersects(obj2.getBounds());
}
Also, there's a specific site for game related questions. Go to Game Development Stack Exchange

You need to check if you hit the object, meaning, if the click coordinates are within the object's Rectangle.
if( playerRocket.x + playerRocket.width >= clickX && playerRocket.x <= clickX &&
playerRocket.y + playerRocket.height >= clickY && playerRocket.Y <= clickY ) {
playerRocket.crashed = true;
}