In short:
I create Polygon object with a help of this method:
public static float[][] getPolygonArrays(float cx, float cy, float R, int sides) {
float[] x = new float[sides];
float[] y = new float[sides];
double thetaInc = 2 * Math.PI / sides;
double theta = (sides % 2 == 0) ? thetaInc : -Math.PI / 2;
for (int j = 0; j < sides; j++) {
x[j] = (float) (cx + R * Math.cos(theta));
y[j] = (float) (cy + R * Math.sin(theta));
theta += thetaInc;
}
return new float[][]{x, y};
}
and merge it to one dimension array with:
public static float[] mergeCoordinates(float[][] vertices) throws Exception {
if (vertices.length != 2 || vertices[0].length != vertices[1].length) throw new Exception("No valid data");
ArrayList<Float> mergedArrayList = new ArrayList<Float>();
float[] mergedArray = new float[vertices[0].length * 2];
for(int i = 0; i < vertices[0].length; i++) {
mergedArrayList.add(vertices[0][i]);
mergedArrayList.add(vertices[1][i]);
}
int i = 0;
for (Float f : mergedArrayList) {
mergedArray[i++] = (f != null ? f : Float.NaN);
}
return mergedArray;
}
I use 0 as value for X and Y for all newly created Polygons (named in code as Platform). And result of method mergeCoordinates i pass to method setVertices of Polygon object.
After this step i do setPosition with x = Gdx.graphics.getWidth()/2 and y = Gdx.graphics.getHeight()/2. Polygons are positioned good, right on the game screen center.
Than i create a new one Polygon, which must use origin coordinates from first Polygon object, this new polygon i named Figure. To set origin coordinates i use method setOrigin of Polygon class, and use X and Y of Platform Polygon object.
When i run method rotate of Platform Polygon object i also rotate Figure Polygon object, and Figure must rotate around origin point, center of Platform. But it does not.
Figure do rotation around bottom right corner.
For example:
my screen size is 640 x 480. Center point will be 320 x 240. This is X and Y of Platform Polygon object, i checked it with getX and getY of Polygon. I create Figure at 0,0, do setPosition(320, 200) (this is preferred orbit distance for figure to platform). And Figure positioned also good.
I run setOrigin(320, 240) for Figure Polygon Object.
I run rotate for Figure object. And it somehow think that right bottom corner have coordinates x = 320 and y = 240 and do rotation around this point.
Any could help me to solve this problem?
More details on problem you can find below(details, images, gifs, schemes and also sources).
More detailed part starts here
i'm trying to understand how coordinate system in libgdx work, cause i have a problem with positioning objects in game world.
I created simple application, with one big Red Polygon object(Platform in code),
10 White Triangle Polygons(Sector in code) which are included into big polygon object and inherits it's behavior(such like rotate, moveTo and etc).
Than i added inside each Sector one Green Polyline(Direction in code) from first vertice of Sector Polygon to midle point of the opposite side to first point.
This is technical line and i will use it's vertices(coordinates of two points) to move small Red Polygon Object(Figure in code), from center to oposite side to center point of Sector.
When i click on Stage and click coordinates are inside Platform i rotate it to the left or to the right(depends on where click was made). On rotate all Sectors and technical lines are rotated correctly. https://i.stack.imgur.com/vF8sq.gif (670Kb)
As you can see on gif, figures rotates around theire's center point. I found that Polygon class has method setOrigin(float x, float y) and in annotation to this method said next:
/** Sets the origin point to which all of the polygon's local vertices are relative to. */
So i tried to use this method, set origin X of Figure as center X of Platform and origin Y as center Y of Platform, and tried to rotate Platform. https://i.stack.imgur.com/CrDTF.gif (1.06Mb)
As you can see, Figure polygon think that his origin coordinates are at right bottom corner. And Figure do rotation around right bottom corner.
I changed origin to next values: x = 50 and y = 50, here is a result: https://i.stack.imgur.com/sUoLw.gif (640Kb)
I cannot get why it behave like that. What should i change in my logic?
I have not much classes in my project. I removed all imports and getters/setter to reduce amount of lines.
If it is necessary i could provide entire project.
GameScreen code:
public class GameScreen extends DefaultScreen {
private final GameWorld world;
private final GameRenderer renderer;
public GameScreen() {
world = new GameWorld();
renderer = new GameRenderer(world);
}
@Override
public void render(float delta) {
world.update(delta);
renderer.render();
}
@Override
public void resize(int width, int height) {
world.resize(width, height);
}
}
GameWorld code:
public class GameWorld {
private ArrayList < Platform > platforms = new ArrayList < Platform > ();
private OrthographicCamera camera;
private Stage stage;
private Array < Figure > activeFigures;
private Pool < Figure > figuresPool;
private long lastFigureTime = TimeUtils.nanoTime();
public GameWorld() {
setCamera(new OrthographicCamera());
getCamera().setToOrtho(true, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
setStage(new Stage());
getStage().setViewport(new ScreenViewport(getCamera()));
initializePools();
createPlatforms();
getStage().addListener(new InputListener() {
public boolean touchDown(InputEvent event, float x, float y, int pointer, int button) {
float degrees = Config.PLATFORM_ROTATE_DEGREES;
if (x <= Gdx.graphics.getWidth() / 2) {
degrees *= -1;
}
int i = getPlatforms().size();
while (i-- > 0) {
Platform platform = getPlatforms().get(i);
if (!platform.isLocked() && platform.isRotatable() && platform.getShape().getPolygon().contains(x, y)) {
platform.addAction(Actions.rotateBy(degrees, 1, Interpolation.bounceOut));
break;
}
}
return true;
}
});
Gdx.input.setInputProcessor(getStage());
}
private void initializePools() {
setActiveFigures(new Array < Figure > ());
setFiguresPool(new Pool < Figure > () {@Override
protected Figure newObject() {
return new Figure();
}
});
}
private void createPlatforms() {
float max = Gdx.graphics.getHeight() / (Gdx.graphics.getWidth() / (Gdx.graphics.getWidth() / 2));
float x = Gdx.graphics.getWidth() / 2;
float y = Gdx.graphics.getHeight() / 2;
float sides = 10f;
Color color = Color.RED;
createPlatform(x, y, max * Config.THIRD_PLATFORM_RADIUS_MULTIPLIER, sides, color, true, false, false, null);
}
private Platform createPlatform(float x, float y, float radius, float sides, Color color, boolean rotatable, boolean locked, boolean isEmpty, Platform relatedTo) {
Platform platform = new Platform(0, 0, radius, sides, color, isEmpty, this);
platform.moveTo(x, y);
platform.setRotatable(rotatable);
platform.setLocked(locked);
getPlatforms().add(platform);
getStage().addActor(platform);
if (relatedTo != null) {
relatedTo.addRelation(platform);
}
return platform;
}
private Figure createFigure(float x, float y) {
Figure figure = getFiguresPool().obtain();
figure.init(this, 0, 0, 10f, 4f, Color.DARK_GRAY);
figure.moveTo(x, y);
getActiveFigures().add(figure);
getStage().addActor(figure);
return figure;
}
public void spawnFigure() {
if (getActiveFigures().size >= 10) return;
if (TimeUtils.nanoTime() - getLastFigureTime() <= 2000000000) return;
Platform platform = null;
for (Platform p: getPlatforms()) {
if (!p.isEmpty()) {
platform = p;
break;
}
}
if (platform == null) {
setLastFigureTime(TimeUtils.nanoTime());
return;
}
Sector sector = platform.getSectors().get(MathUtils.random(platform.getSectors().size() - 1));
float x = platform.getX();
float y = platform.getY();
Figure figure = createFigure(x, y);
figure.origin(x, y);
x = sector.getDirection().getTransformedVertices()[2];
y = sector.getDirection().getTransformedVertices()[3];
figure.addAction(Actions.moveTo(x, y, 1));
setLastFigureTime(TimeUtils.nanoTime());
}
public void update(float delta) {
updatePlatforms(delta);
updateFigures(delta);
spawnFigure();
}
private void updatePlatforms(float delta) {
for (Platform platform: getPlatforms()) {
platform.update(delta);
}
}
private void updateFigures(float delta) {
Figure figure;
int figures = getActiveFigures().size;
for (int i = figures; --i >= 0;) {
figure = getActiveFigures().get(i);
if (figure.isAlive() == false) {
getActiveFigures().removeIndex(i);
getFiguresPool().free(figure);
} else {
figure.update(delta);
}
}
}
public void resize(int width, int height) {
getCamera().setToOrtho(true, width, height);
getStage().getViewport().update(width, height, true);
for (Platform platform: getPlatforms()) {
platform.resize(true, width, height);
}
for (Figure figure: getActiveFigures()) {
figure.resize(true, width, height);
}
}
}
GameRenderer code:
public class GameRenderer {
private ShapeRenderer shapeRenderer;
private GameWorld world;
private SpriteBatch spriteBatch;
public GameRenderer(GameWorld world) {
setWorld(world);
setShapeRenderer(new ShapeRenderer());
getShapeRenderer().setProjectionMatrix(getWorld().getCamera().combined);
setSpriteBatch(new SpriteBatch());
getSpriteBatch().setProjectionMatrix(getWorld().getCamera().combined);
}
public void render() {
Gdx.gl.glClearColor(0f, 0.2f, 0.4f, 1f);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
getWorld().getCamera().update();
getSpriteBatch().setProjectionMatrix(getWorld().getCamera().combined);
getShapeRenderer().setProjectionMatrix(getWorld().getCamera().combined);
getWorld().getStage().act(Gdx.graphics.getDeltaTime());
getWorld().getStage().draw();
renderGameObjects();
}
private void renderGameObjects() {
renderPlatforms();
renderFigures();
}
private void renderFigures() {
getShapeRenderer().begin(ShapeRenderer.ShapeType.Line);
for (Figure figure: getWorld().getActiveFigures()) {
figure.render(getSpriteBatch(), getShapeRenderer());
}
getShapeRenderer().end();
}
private void renderPlatforms() {
getShapeRenderer().begin(ShapeRenderer.ShapeType.Line);
for (Platform platform: world.getPlatforms()) {
platform.render(getSpriteBatch(), getShapeRenderer());
}
getShapeRenderer().end();
}
}
Platform code:
public class Platform extends GameObject {
private ArrayList < Sector > sectors = new ArrayList < Sector > ();
private ArrayList < Platform > relations = new ArrayList < Platform > ();
private boolean rotatable = true;
private boolean locked = false;
private void initialize(float cx, float cy, float radius, float sides, Color color) {
setPosition(cx, cy);
setRadius(radius);
setShape(ShapeType.POLYGON.getInstance(new float[] {
cx, cy, radius, sides
}, color));
}
public Platform(float cx, float cy, float radius, float sides, Color color, boolean isEmpty, GameWorld gameWorld) {
setGameWorld(gameWorld);
initialize(cx, cy, radius, sides, color);
setEmpty(isEmpty);
if (!isEmpty()) {
generateSectors();
}
}
private void generateSectors() {
float[] vertices = getShape().getVertices();
for (int i = 0; i < vertices.length; i += 2) {
try {
Color color = Color.WHITE;
if (i + 3 > vertices.length) {
getSectors().add(new Sector(new float[] {
getX(), getY(), vertices[i], vertices[i + 1], vertices[0], vertices[1]
}, color, this, i / 2));
} else {
getSectors().add(new Sector(new float[] {
getX(), getY(), vertices[i], vertices[i + 1], vertices[i + 2], vertices[i + 3]
}, color, this, i / 2));
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
public void rotateBy(float degrees) {
setRotation(degrees);
getShape().rotate(degrees);
for (Sector sector: getSectors()) {
sector.rotate(degrees);
}
for (Platform platform: getRelations()) {
platform.rotateBy(degrees);
}
for (Figure figure: getGameWorld().getActiveFigures()) {
figure.rotate(degrees);
}
}
@Override
public void moveTo(float x, float y) {
super.moveTo(x, y);
getShape().moveTo(x, y);
for (Sector sector: getSectors()) {
sector.moveTo(x, y);
}
for (Platform platform: getRelations()) {
platform.moveTo(x, y);
}
}
public void addRelation(Platform platform) {
if (platform.equals(this)) return;
getRelations().add(platform);
}
@Override
public void update(float delta) {
for (Sector sector: getSectors()) {
sector.update(delta);
}
}
@Override
public void dispose() {
for (Sector sector: getSectors()) {
sector.dispose();
}
}
@Override
public void render(SpriteBatch spriteBatch, ShapeRenderer shapeRenderer) {
render(spriteBatch);
if (Config.DEBUG_LAYOUTS) render(shapeRenderer);
for (Sector sector: getSectors()) {
sector.render(spriteBatch, shapeRenderer);
}
}
private void render(ShapeRenderer shapeRenderer) {
shapeRenderer.setColor(getShape().getColor());
shapeRenderer.polygon(getShape().getVertices());
}
public void resize(boolean reposition, int width, int height) {
if (reposition) {
moveTo(width / 2, height / 2);
}
}
}
Sector code:
public class Sector extends GameObject {
private Polyline direction;
private float[] vertices;
private Platform platform;
private int sectorId;
public Sector(float[] vertices, Color color, Platform platform, int sectorId) throws Exception {
setSectorId(sectorId);
setVertices(vertices);
initialize(vertices, color, platform);
}
private void createDirection() {
float[] vertices = getShape().getPolygon().getVertices();
float x1 = vertices[0];
float y1 = vertices[1];
float x2 = (vertices[2]+vertices[4])/2;
float y2 = (vertices[3]+vertices[5])/2;
setDirection(new Polyline(new float[]{ x1, y1, x2, y2 }));
}
public Sector(float[] vertices, Color color, boolean isEmpty) throws Exception {
initialize(vertices, color);
setEmpty(isEmpty);
}
private void initialize(float[] vertices, Color color) throws Exception {
if (vertices.length != 6) {
throw new Exception("Sector constructor expects 6 vertices");
}
setShape(ShapeType.TRIANGLE.getInstance(vertices, color));
createDirection();
}
private void initialize(float[] vertices, Color color, Platform platform) throws Exception {
if (vertices.length != 6) {
throw new IllegalArgumentException("Sector constructor expects 6 vertices");
}
setShape(ShapeType.TRIANGLE.getInstance(vertices, color));
setPlatform(platform);
createDirection();
}
public void rotate(float degrees) {
getShape().rotate(degrees);
getDirection().rotate(degrees);
}
@Override
public void moveTo(float x, float y) {
super.moveTo(x, y);
getShape().moveTo(x, y);
getDirection().setPosition(x, y);
}
@Override
public void render(SpriteBatch spriteBatch, ShapeRenderer shapeRenderer) {
render(spriteBatch);
if (Config.DEBUG_LAYOUTS) render(shapeRenderer);
}
private void render(ShapeRenderer shapeRenderer) {
shapeRenderer.setColor(getShape().getColor());
shapeRenderer.polygon(getShape().getVertices());
shapeRenderer.setColor(Color.GREEN);
shapeRenderer.line(getDirection().getTransformedVertices()[0], getDirection().getTransformedVertices()[1], getDirection().getTransformedVertices()[2], getDirection().getTransformedVertices()[3]);
}
}
Figure code:
public class Figure extends GameObject {
private GameWorld world;
public void init(GameWorld world, float cx, float cy, float radius, float sides, Color color) {
super.init();
setWorld(world);
initialize(cx, cy, radius, sides, color);
}
private void initialize(float cx, float cy, float radius, float sides, Color color) {
super.moveTo(cx, cy);
setRadius(radius);
setShape(ShapeType.POLYGON.getInstance(new float[] {
cx, cy, radius, sides
}, color));
}
@Override
public void moveTo(float x, float y) {
super.moveTo(x, y);
getShape().moveTo(x, y);
}
@Override
public void setPosition(float x, float y) {
if (!isAllowedToFlyFuther()) {
clearActions();
return;
}
moveTo(x, y);
}
private boolean isAllowedToFlyFuther() {
for (Figure figure: getWorld().getActiveFigures()) {
if (!figure.equals(this) && Intersector.overlapConvexPolygons(figure.getShape().getPolygon(), getShape().getPolygon())) {
return false;
}
}
return true;
}
@Override
public void reset() {
super.reset();
remove();
}
@Override
public void update(float delta) {}
private void render(SpriteBatch spriteBatch) {}
@Override
public void dispose() {}
@Override
public void render(SpriteBatch spriteBatch, ShapeRenderer shapeRenderer) {
render(spriteBatch);
if (Config.DEBUG_LAYOUTS) render(shapeRenderer);
}
private void render(ShapeRenderer shapeRenderer) {
shapeRenderer.setColor(getShape().getColor());
shapeRenderer.polygon(getShape().getVertices());
}
public void rotate(float degrees) {
setRotation(degrees);
getShape().rotate(degrees);
}
public void origin(float originX, float originY) {
setOrigin(originX, originY);
getShape().setOrigin(originX, originY);
}
public void resize(boolean reposition, int width, int height) {
if (reposition) {
//TODO: implement reposition for figures
}
}
}
GameObject code:
public abstract class GameObject extends Actor implements Poolable {
private int speed = 200;
private int baseSpeed = 200;
private boolean alive;
private float radius;
private GameWorld gameWorld;
private Shape shape;
private boolean empty = false;
public GameObject() {
setAlive(false);
}
public void init() {
setAlive(true);
}
public void reset() {
setAlive(false);
}
public abstract void update(float delta);
public abstract void render(SpriteBatch spriteBatch, ShapeRenderer shapeRenderer);
public abstract void dispose();
public void moveTo(float x, float y) {
super.setPosition(x, y);
}
}
Shape code:
public class Shape {
private Color color = new Color(Color.RED);
private float[] vertices;
private int sides;
private float radius;
private Polygon polygon = new Polygon();
public void rotate(float degrees) {
getPolygon().rotate(degrees);
setVertices(getPolygon().getTransformedVertices());
}
public void moveTo(float x, float y) {
getPolygon().setPosition(x, y);
setVertices(getPolygon().getTransformedVertices());
}
public void setOrigin(float originX, float originY) {
getPolygon().setOrigin(originX, originY);
setVertices(getPolygon().getTransformedVertices());
}
public void scale(float ratio) {
getPolygon().setScale(ratio, ratio);
setVertices(getPolygon().getTransformedVertices());
}
}
ShapeType code:
public enum ShapeType {
POLYGON {@Override
public Shape getInstance(float[] settings, Color color) {
try {
return new PolygonShape(settings, color);
} catch (Exception e) {
e.printStackTrace();
}
return new BaseShape();
}
},
TRIANGLE {@Override
public Shape getInstance(float[] settings, Color color) {
try {
return new TriangleShape(settings, color);
} catch (Exception e) {
e.printStackTrace();
}
return new BaseShape();
}
};
public abstract Shape getInstance(float[] settings, Color color);
}
PolygonShape code:
public class PolygonShape extends Shape {
public PolygonShape(float[] settings, Color color) throws Exception {
if (settings.length < 4) {
throw new IllegalArgumentException("Polygon shape constructor expects minimum 4 items in settings");
}
setSides((int) settings[3]);
setRadius(settings[2]);
setVertices(Utils.mergeCoordinates(Utils.getPolygonArrays(settings[0], settings[1], settings[2], (int) settings[3])));
getPolygon().setVertices(getVertices());
}
}
TriangleShape code:
public class TriangleShape extends Shape {
public TriangleShape(float[] settings, Color color) throws Exception {
if (settings.length < 6) {
throw new IllegalArgumentException("Triangle shape constructor expects minimum 6 items in settings");
}
setVertices(settings);
setColor(color);
getPolygon().setVertices(getVertices());
}
}
Utils code:
public class Utils {
public static float[] mergeCoordinates(float[][] vertices) throws Exception {
if (vertices.length != 2 || vertices[0].length != vertices[1].length) throw new Exception("No valid data");
ArrayList < Float > mergedArrayList = new ArrayList < Float > ();
float[] mergedArray = new float[vertices[0].length * 2];
for (int i = 0; i < vertices[0].length; i++) {
mergedArrayList.add(vertices[0][i]);
mergedArrayList.add(vertices[1][i]);
}
int i = 0;
for (Float f: mergedArrayList) {
mergedArray[i++] = (f != null ? f : Float.NaN);
}
return mergedArray;
}
public static float[][] getPolygonArrays(float cx, float cy, float R, int sides) {
float[] x = new float[sides];
float[] y = new float[sides];
double thetaInc = 2 * Math.PI / sides;
double theta = (sides % 2 == 0) ? thetaInc : -Math.PI / 2;
for (int j = 0; j < sides; j++) {
x[j] = (float)(cx + R * Math.cos(theta));
y[j] = (float)(cy + R * Math.sin(theta));
theta += thetaInc;
}
return new float[][] {
x, y
};
}
}
Config code:
public class Config {
public static final String LOG = TheGame.class.getSimpleName();
public static final boolean DEBUG_LAYOUTS = true;
public static final boolean SHOW_LOG = false;
public static final float PLATFORM_ROTATE_DEGREES = 36;
}
DesktopLauncher code:
public class DesktopLauncher {
public static void main(String[] arg) {
LwjglApplicationConfiguration config = new LwjglApplicationConfiguration();
config.title = "The Game!";
config.width = 1920 / 3;
config.height = 1080 / 3;
new LwjglApplication(new TheGame(), config);
}
}
Project structure:
Platform object structure and dependencies:
Render objects workflow
