Ellipse Curve Bounds
Demonstrates how to calculate and visualize the bounding box of an interactive Ellipse curve. Includes real-time controls for radius, rotation, and start/end angles.
800 × 600
class Example extends Phaser.Scene
{
text;
path;
curve;
bounds;
graphics;
constructor()
{
super({
key: 'Example'
});
}
preload ()
{
this.load.setBaseURL('https://cdn.phaserfiles.com/v410');
this.load.spritesheet('dragcircle', 'assets/sprites/dragcircle.png', { frameWidth: 16 });
}
create ()
{
const sliderGraphics = this.add.graphics();
this.path = { t: 0, vec: new Phaser.Math.Vector2() };
this.bounds = new Phaser.Geom.Rectangle();
this.curve = new Phaser.Curves.Ellipse(400, 300, 100, 150);
this.curve.getBounds(this.bounds);
this.createSlider(sliderGraphics, 100, 10, 'width', 500, 0, 400, 100, this.curve.setXRadius);
this.createSlider(sliderGraphics, 100, 30, 'height', 500, 0, 300, 150, this.curve.setYRadius);
this.createSlider(sliderGraphics, 100, 50, 'start', 500, 0, 360, 0, this.curve.setStartAngle);
this.createSlider(sliderGraphics, 100, 70, 'end', 500, 0, 360, 360, this.curve.setEndAngle);
this.createSlider(sliderGraphics, 100, 90, 'angle', 500, 0, 360, 0, this.curve.setRotation);
const centerPoint = this.add.image(this.curve.p0.x, this.curve.p0.y, 'dragcircle', 0).setInteractive();
centerPoint.setData('control', 'center').setData('vector', this.curve.p0).setName("centerpoint");
this.input.setDraggable(centerPoint);
this.input.on(Phaser.Input.Events.DRAG, function (event, gameObject) {
gameObject.setFrame(1);
});
this.input.on(Phaser.Input.Events.DRAG, function (event, gameObject) {
if (gameObject.data.get('control') === 'center')
{
gameObject.x = event.dragX;
gameObject.y = event.dragY;
gameObject.data.get('vector').set(event.dragX, event.dragY);
}
});
this.input.on(Phaser.Input.Events.DRAG_END, function (event, gameObject) {
gameObject.setFrame(0);
});
this.tweens.add({
targets: this.path,
t: 1,
ease: 'Linear',
duration: 4000,
repeat: -1
});
// Debug this.graphics
this.graphics = this.add.graphics();
}
update ()
{
this.graphics.clear();
this.curve.getBounds(this.bounds);
// Draw the this.bounds
this.graphics.lineStyle(1, 0x00ff00, 1).strokeRectShape(this.bounds);
this.graphics.lineStyle(2, 0xffffff, 1);
this.curve.draw(this.graphics, 64);
this.curve.getPoint(this.path.t, this.path.vec);
this.graphics.fillStyle(0xffff00, 1);
this.graphics.fillCircle(this.path.vec.x, this.path.vec.y, 8);
}
createSlider (graphics, x, y, label, width, min, max, value, callback)
{
// Default value
value = Phaser.Math.Clamp(value, min, max);
graphics.lineStyle(1, 0xffffff, 1);
graphics.lineBetween(x, y + 8, x + width, y + 8);
this.text = this.add.text(x - 10, y, label + ':', { font: '16px Courier', fill: '#00ff00' }).setOrigin(1, 0);
const textValue = this.add.text(x + width + 10, y, value.toFixed(2), { font: '16px Courier', fill: '#00ff00' });
const image = this.add.image(x, y + 8, 'dragcircle', 0).setInteractive();
image.setData('labelValue', textValue);
image.setData('left', x);
image.setData('right', x + width);
this.input.setDraggable(image);
// Drag limits
image.setData('label', label);
// The range the control is allowed to be within (the actual values, not the percentage or pixels)
image.setData('min', min);
image.setData('max', max);
image.setData('value', value);
// The scale is how many pixels = 1 unit of range
const scale = max / width;
image.setData('scale', scale);
const p = Phaser.Math.Percent(value, min, max);
// console.log('width', width);
// console.log('min', min);
// console.log('max', max);
// console.log('value', value, 'p:', p, '%');
// console.log('scale', scale);
image.x += p * width;
image.setData('callback', callback);
this.input.on(Phaser.Input.Events.DRAG, (pointer, gameObject) => {
if(gameObject.name !== "centerpoint")
{
this.updateSlider(gameObject, pointer, pointer.x, pointer.y)
}
});
}
updateSlider (handle, pointer, dragX, dragY)
{
const min = handle.getData('min');
const max = handle.getData('max');
const scale = handle.getData('scale');
const left = handle.getData('left');
const right = handle.getData('right');
dragX = Phaser.Math.Clamp(dragX, left, right);
handle.x = dragX;
// Calculate the value
const value = (dragX - left) * scale;
handle.setData('value', value);
handle.getData('labelValue').setText(value.toFixed(2));
const callback = handle.getData('callback');
callback.call(this.curve, value);
}
}
const config = {
scale: { mode: Phaser.Scale.FIT },
type: Phaser.AUTO,
width: 800,
height: 600,
backgroundColor: '#2d2d2d',
parent: 'game-container',
scene: Example
};
const game = new Phaser.Game(config);