175 lines
6.4 KiB
TypeScript
175 lines
6.4 KiB
TypeScript
module TK.SpaceTac {
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// Find the nearest intersection between a line and a circle
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// Circle is supposed to be centered at (0,0)
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// Nearest intersection to (x1,y1) is returned
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function intersectLineCircle(x1: number, y1: number, x2: number, y2: number, r: number): [number, number] | null {
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let a = y2 - y1;
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let b = -(x2 - x1);
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let c = -(a * x1 + b * y1);
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let x0 = -a * c / (a * a + b * b), y0 = -b * c / (a * a + b * b);
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let EPS = 10e-8;
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if (c * c > r * r * (a * a + b * b) + EPS) {
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return null;
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} else if (Math.abs(c * c - r * r * (a * a + b * b)) < EPS) {
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return [x0, y0];
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} else {
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let d = r * r - c * c / (a * a + b * b);
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let mult = Math.sqrt(d / (a * a + b * b));
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let ax, ay, bx, by;
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ax = x0 + b * mult;
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bx = x0 - b * mult;
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ay = y0 - a * mult;
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by = y0 + a * mult;
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let candidates: [number, number][] = [
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[x0 + b * mult, y0 - a * mult],
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[x0 - b * mult, y0 + a * mult]
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]
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return minBy(candidates, ([x, y]) => Math.sqrt((x - x1) * (x - x1) + (y - y1) * (y - y1)));
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}
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}
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// Target for a capability
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// This could be a location in space, or a ship
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export class Target {
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// Coordinates of the target
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x: number
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y: number
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// If the target is a ship, this attribute will be set
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ship_id: RObjectId | null
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// Standard constructor
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constructor(x: number, y: number, ship: Ship | null = null) {
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this.x = x;
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this.y = y;
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this.ship_id = ship ? ship.id : null;
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}
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jasmineToString() {
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if (this.ship_id) {
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return `(${this.x},${this.y}) ship_id=${this.ship_id}}`;
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} else {
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return `(${this.x},${this.y})`;
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}
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}
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// Constructor to target a single ship
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static newFromShip(ship: Ship): Target {
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return new Target(ship.arena_x, ship.arena_y, ship);
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}
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// Constructor to target a location in space
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static newFromLocation(x: number, y: number): Target {
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return new Target(x, y, null);
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}
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// Get distance to another target
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getDistanceTo(other: { x: number, y: number }): number {
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var dx = other.x - this.x;
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var dy = other.y - this.y;
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return Math.sqrt(dx * dx + dy * dy);
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}
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// Get the normalized angle, in radians, to another target
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getAngleTo(other: { x: number, y: number }): number {
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var dx = other.x - this.x;
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var dy = other.y - this.y;
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return Math.atan2(dy, dx);
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}
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/**
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* Returns true if the target is a ship
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*/
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isShip(): boolean {
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return this.ship_id !== null;
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}
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/**
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* Get the targetted ship in a battle
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*/
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getShip(battle: Battle): Ship | null {
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if (this.isShip()) {
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return battle.getShip(this.ship_id);
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} else {
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return null;
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}
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}
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// Check if a target is in range from a specific point
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isInRange(x: number, y: number, radius: number): boolean {
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var dx = this.x - x;
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var dy = this.y - y;
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var length = Math.sqrt(dx * dx + dy * dy);
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return (length <= radius);
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}
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// Constraint a target, to be in a given range from a specific point
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// May return the original target if it's already in radius
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constraintInRange(x: number, y: number, radius: number): Target {
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var dx = this.x - x;
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var dy = this.y - y;
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var length = Math.sqrt(dx * dx + dy * dy);
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if (length <= radius) {
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return this;
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} else {
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var factor = radius / length;
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return Target.newFromLocation(x + dx * factor, y + dy * factor);
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}
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}
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// Force a target to stay out of a given circle
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// If the target is in the circle, it will be moved to the nearest intersection between targetting line
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// and the circle
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// May return the original target if it's already out of the circle
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moveOutOfCircle(circlex: number, circley: number, radius: number, sourcex: number, sourcey: number): Target {
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var dx = this.x - circlex;
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var dy = this.y - circley;
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var length = Math.sqrt(dx * dx + dy * dy);
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if (length >= radius) {
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// Already out of circle
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return this;
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} else {
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// Find nearest intersection with circle
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var res = intersectLineCircle(sourcex - circlex, sourcey - circley, dx, dy, radius);
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if (res) {
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return Target.newFromLocation(res[0] + circlex, res[1] + circley);
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} else {
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return this;
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}
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}
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}
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/**
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* Keep the target inside a rectangle
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*
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* May return the original target if it's already inside the rectangle
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*/
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keepInsideRectangle(xmin: number, ymin: number, xmax: number, ymax: number, sourcex: number, sourcey: number): Target {
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let length = this.getDistanceTo({ x: sourcex, y: sourcey });
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let result: Target = this;
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if (result.x < xmin) {
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let factor = (xmin - sourcex) / (result.x - sourcex);
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length *= factor;
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result = result.constraintInRange(sourcex, sourcey, length);
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}
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if (result.x > xmax) {
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let factor = (xmax - sourcex) / (result.x - sourcex);
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length *= factor;
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result = result.constraintInRange(sourcex, sourcey, length);
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}
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if (result.y < ymin) {
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let factor = (ymin - sourcey) / (result.y - sourcey);
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length *= factor;
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result = result.constraintInRange(sourcex, sourcey, length);
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}
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if (result.y > ymax) {
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let factor = (ymax - sourcey) / (result.y - sourcey);
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length *= factor;
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result = result.constraintInRange(sourcex, sourcey, length);
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}
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return result;
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}
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}
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}
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