phaser/Phaser/Motion.ts

/// <reference path="Game.ts" />
/// <reference path="gameobjects/Sprite.ts" />

/**
* Phaser - Motion
*
* The Motion class contains lots of useful functions for moving game objects around in world space.
*/

module Phaser {

    export class Motion {

        constructor(game: Game) {
            this.game = game;
        }

        public game: Game;

        /**
        * Given the angle and speed calculate the velocity and return it as a Point
        *
        * @param {number} angle The angle (in degrees) calculated in clockwise positive direction (down = 90 degrees positive, right = 0 degrees positive, up = 90 degrees negative)
        * @param {number} speed The speed it will move, in pixels per second sq
        *
        * @return {Point} A Point where Point.x contains the velocity x value and Point.y contains the velocity y value
        */
        public velocityFromAngle(angle: number, speed: number): Point {

            if (isNaN(speed))
            {
                speed = 0;
            }

            var a: number = this.game.math.degreesToRadians(angle);

            return new Point((Math.cos(a) * speed), (Math.sin(a) * speed));

        }

        /**
		 * Sets the source Sprite x/y velocity so it will move directly towards the destination Sprite at the speed given (in pixels per second)<br>
		 * If you specify a maxTime then it will adjust the speed (over-writing what you set) so it arrives at the destination in that number of seconds.<br>
		 * Timings are approximate due to the way Flash timers work, and irrespective of SWF frame rate. Allow for a variance of +- 50ms.<br>
		 * The source object doesn't stop moving automatically should it ever reach the destination coordinates.<br>
		 * If you need the object to accelerate, see accelerateTowardsObject() instead
		 * Note: Doesn't take into account acceleration, maxVelocity or drag (if you set drag or acceleration too high this object may not move at all)
		 *
		 * @param {Sprite} source The Sprite on which the velocity will be set
		 * @param {Sprite} dest The Sprite where the source object will move to
		 * @param {number} speed The speed it will move, in pixels per second (default is 60 pixels/sec)
		 * @param {number} maxTime Time given in milliseconds (1000 = 1 sec). If set the speed is adjusted so the source will arrive at destination in the given number of ms
		 */
        public moveTowardsObject(source: Sprite, dest: Sprite, speed: number = 60, maxTime: number = 0) {
            var a: number = this.angleBetween(source, dest);

            if (maxTime > 0)
            {
                var d: number = this.distanceBetween(source, dest);

                //	We know how many pixels we need to move, but how fast?
                speed = d / (maxTime / 1000);
            }

            source.body.velocity.x = Math.cos(a) * speed;
            source.body.velocity.y = Math.sin(a) * speed;

        }

        /**
		 * Sets the x/y acceleration on the source Sprite so it will move towards the destination Sprite at the speed given (in pixels per second)<br>
		 * You must give a maximum speed value, beyond which the Sprite won't go any faster.<br>
		 * If you don't need acceleration look at moveTowardsObject() instead.
		 *
		 * @param {Sprite} source The Sprite on which the acceleration will be set
		 * @param {Sprite} dest The Sprite where the source object will move towards
		 * @param {number} speed The speed it will accelerate in pixels per second
		 * @param {number} xSpeedMax The maximum speed in pixels per second in which the sprite can move horizontally
		 * @param {number} ySpeedMax The maximum speed in pixels per second in which the sprite can move vertically
		 */
        public accelerateTowardsObject(source: Sprite, dest: Sprite, speed: number, xSpeedMax: number, ySpeedMax: number) {
            var a: number = this.angleBetween(source, dest);

            source.body.velocity.x = 0;
            source.body.velocity.y = 0;

            source.body.acceleration.x = Math.cos(a) * speed;
            source.body.acceleration.y = Math.sin(a) * speed;

            source.body.maxVelocity.x = xSpeedMax;
            source.body.maxVelocity.y = ySpeedMax;

        }

        /**
		 * Move the given Sprite towards the mouse pointer coordinates at a steady velocity
		 * If you specify a maxTime then it will adjust the speed (over-writing what you set) so it arrives at the destination in that number of seconds.<br>
		 * Timings are approximate due to the way Flash timers work, and irrespective of SWF frame rate. Allow for a variance of +- 50ms.<br>
		 * The source object doesn't stop moving automatically should it ever reach the destination coordinates.<br>
		 *
		 * @param {Sprite} source The Sprite to move
		 * @param {number} speed The speed it will move, in pixels per second (default is 60 pixels/sec)
		 * @param {number} maxTime Time given in milliseconds (1000 = 1 sec). If set the speed is adjusted so the source will arrive at destination in the given number of ms
		 */
        public moveTowardsMouse(source: Sprite, speed: number = 60, maxTime: number = 0) {
            var a: number = this.angleBetweenMouse(source);

            if (maxTime > 0)
            {
                var d: number = this.distanceToMouse(source);

                //	We know how many pixels we need to move, but how fast?
                speed = d / (maxTime / 1000);
            }

            source.body.velocity.x = Math.cos(a) * speed;
            source.body.velocity.y = Math.sin(a) * speed;

        }

        /**
		 * Sets the x/y acceleration on the source Sprite so it will move towards the mouse coordinates at the speed given (in pixels per second)<br>
		 * You must give a maximum speed value, beyond which the Sprite won't go any faster.<br>
		 * If you don't need acceleration look at moveTowardsMouse() instead.
		 *
		 * @param {Sprite} source The Sprite on which the acceleration will be set
		 * @param {number} speed The speed it will accelerate in pixels per second
		 * @param {number} xSpeedMax The maximum speed in pixels per second in which the sprite can move horizontally
		 * @param {number} ySpeedMax The maximum speed in pixels per second in which the sprite can move vertically
		 */
        public accelerateTowardsMouse(source: Sprite, speed: number, xSpeedMax: number, ySpeedMax: number) {
            var a: number = this.angleBetweenMouse(source);

            source.body.velocity.x = 0;
            source.body.velocity.y = 0;

            source.body.acceleration.x = Math.cos(a) * speed;
            source.body.acceleration.y = Math.sin(a) * speed;

            source.body.maxVelocity.x = xSpeedMax;
            source.body.maxVelocity.y = ySpeedMax;
        }

        /**
		 * Sets the x/y velocity on the source Sprite so it will move towards the target coordinates at the speed given (in pixels per second)<br>
		 * If you specify a maxTime then it will adjust the speed (over-writing what you set) so it arrives at the destination in that number of seconds.<br>
		 * Timings are approximate due to the way Flash timers work, and irrespective of SWF frame rate. Allow for a variance of +- 50ms.<br>
		 * The source object doesn't stop moving automatically should it ever reach the destination coordinates.<br>
		 *
		 * @param {Sprite} source The Sprite to move
		 * @param {Point} target The Point coordinates to move the source Sprite towards
		 * @param {number} speed The speed it will move, in pixels per second (default is 60 pixels/sec)
		 * @param {number} maxTime Time given in milliseconds (1000 = 1 sec). If set the speed is adjusted so the source will arrive at destination in the given number of ms
		 */
        public moveTowardsPoint(source: Sprite, target: Point, speed: number = 60, maxTime: number = 0) {
            var a: number = this.angleBetweenPoint(source, target);

            if (maxTime > 0)
            {
                var d: number = this.distanceToPoint(source, target);

                //	We know how many pixels we need to move, but how fast?
                speed = d / (maxTime / 1000);
            }

            source.body.velocity.x = Math.cos(a) * speed;
            source.body.velocity.y = Math.sin(a) * speed;
        }

        /**
		 * Sets the x/y acceleration on the source Sprite so it will move towards the target coordinates at the speed given (in pixels per second)<br>
		 * You must give a maximum speed value, beyond which the Sprite won't go any faster.<br>
		 * If you don't need acceleration look at moveTowardsPoint() instead.
		 *
		 * @param {Sprite} source The Sprite on which the acceleration will be set
		 * @param {Point} target The Point coordinates to move the source Sprite towards
		 * @param {number} speed The speed it will accelerate in pixels per second
		 * @param {number} xSpeedMax The maximum speed in pixels per second in which the sprite can move horizontally
		 * @param {number} ySpeedMax The maximum speed in pixels per second in which the sprite can move vertically
		 */
        public accelerateTowardsPoint(source: Sprite, target: Point, speed: number, xSpeedMax: number, ySpeedMax: number) {
            var a: number = this.angleBetweenPoint(source, target);

            source.body.velocity.x = 0;
            source.body.velocity.y = 0;

            source.body.acceleration.x = Math.cos(a) * speed;
            source.body.acceleration.y = Math.sin(a) * speed;

            source.body.maxVelocity.x = xSpeedMax;
            source.body.maxVelocity.y = ySpeedMax;
        }

        /**
		 * Find the distance between two Sprites, taking their origin into account
		 *
		 * @param {Sprite} a The first Sprite
		 * @param {Sprite} b The second Sprite
		 * @return {number} int Distance (in pixels)
		 */
        public distanceBetween(a: Sprite, b: Sprite): number {
            return Vec2Utils.distance(a.body.position, b.body.position);
        }

        /**
		 * Find the distance from an Sprite to the given Point, taking the source origin into account
		 *
		 * @param {Sprite} a The Sprite
		 * @param {Point} target The Point
		 * @return {number} Distance (in pixels)
		 */
        public distanceToPoint(a: Sprite, target: Point): number {
            var dx: number = (a.x + a.transform.origin.x) - (target.x);
            var dy: number = (a.y + a.transform.origin.y) - (target.y);

            return this.game.math.vectorLength(dx, dy);
        }

        /**
		 * Find the distance (in pixels, rounded) from the object x/y and the mouse x/y
		 *
		 * @param {Sprite} a  Sprite to test against
		 * @return {number} The distance between the given sprite and the mouse coordinates
		 */
        public distanceToMouse(a: Sprite): number {
            var dx: number = (a.x + a.transform.origin.x) - this.game.input.x;
            var dy: number = (a.y + a.transform.origin.y) - this.game.input.y;

            return this.game.math.vectorLength(dx, dy);
        }

        /**
		 * Find the angle (in radians) between an Sprite and an Point. The source sprite takes its x/y and origin into account.
		 * The angle is calculated in clockwise positive direction (down = 90 degrees positive, right = 0 degrees positive, up = 90 degrees negative)
		 *
		 * @param {Sprite} a The Sprite to test from
		 * @param {Point} target The Point to angle the Sprite towards
		 * @param {boolean} asDegrees If you need the value in degrees instead of radians, set to true
		 *
		 * @return {number} The angle (in radians unless asDegrees is true)
		 */
        public angleBetweenPoint(a: Sprite, target: Point, asDegrees: bool = false): number {
            var dx: number = (target.x) - (a.x + a.transform.origin.x);
            var dy: number = (target.y) - (a.y + a.transform.origin.y);

            if (asDegrees)
            {
                return this.game.math.radiansToDegrees(Math.atan2(dy, dx));
            }
            else
            {
                return Math.atan2(dy, dx);
            }
        }

        /**
		 * Find the angle (in radians) between the two Sprite, taking their x/y and origin into account.
		 * The angle is calculated in clockwise positive direction (down = 90 degrees positive, right = 0 degrees positive, up = 90 degrees negative)
		 *
		 * @param {Sprite} a The Sprite to test from
		 * @param {Sprite} b The Sprite to test to
		 * @param {boolean} asDegrees If you need the value in degrees instead of radians, set to true
		 *
		 * @return {number} The angle (in radians unless asDegrees is true)
		 */
        public angleBetween(a: Sprite, b: Sprite, asDegrees: bool = false): number {

            var dx: number = (b.x + b.transform.origin.x) - (a.x + a.transform.origin.x);
            var dy: number = (b.y + b.transform.origin.y) - (a.y + a.transform.origin.y);

            if (asDegrees)
            {
                return this.game.math.radiansToDegrees(Math.atan2(dy, dx));
            }
            else
            {
                return Math.atan2(dy, dx);
            }
        }

        /**
		 * Given the Sprite and speed calculate the velocity and return it as an Point based on the direction the sprite is facing
		 *
		 * @param {Sprite} parent The Sprite to get the facing value from
		 * @param {number} speed The speed it will move, in pixels per second sq
		 *
		 * @return {Point} An Point where Point.x contains the velocity x value and Point.y contains the velocity y value
		 */
        public velocityFromFacing(parent: Sprite, speed: number): Point {
            var a: number;

            if (parent.body.facing == Types.LEFT)
            {
                a = this.game.math.degreesToRadians(180);
            }
            else if (parent.body.facing == Types.RIGHT)
            {
                a = this.game.math.degreesToRadians(0);
            }
            else if (parent.body.facing == Types.UP)
            {
                a = this.game.math.degreesToRadians(-90);
            }
            else if (parent.body.facing == Types.DOWN)
            {
                a = this.game.math.degreesToRadians(90);
            }

            return new Point(Math.cos(a) * speed, Math.sin(a) * speed);

        }

        /**
		 * Find the angle (in radians) between an Sprite and the mouse, taking their x/y and origin into account.
		 * The angle is calculated in clockwise positive direction (down = 90 degrees positive, right = 0 degrees positive, up = 90 degrees negative)
		 *
		 * @param {Sprite} a The Object to test from
		 * @param {boolean} asDegrees If you need the value in degrees instead of radians, set to true
		 *
		 * @return {number} The angle (in radians unless asDegrees is true)
		 */
        public angleBetweenMouse(a: Sprite, asDegrees: bool = false): number {

            //	In order to get the angle between the object and mouse, we need the objects screen coordinates (rather than world coordinates)
            var p: Point = SpriteUtils.getScreenXY(a);

            var dx: number = a.game.input.x - p.x;
            var dy: number = a.game.input.y - p.y;

            if (asDegrees)
            {
                return this.game.math.radiansToDegrees(Math.atan2(dy, dx));
            }
            else
            {
                return Math.atan2(dy, dx);
            }
        }

    }

}