phaser/src/physics/arcade/SeparateY.js

85 lines
3.1 KiB
JavaScript

/**
* @author Richard Davey <rich@photonstorm.com>
* @copyright 2019 Photon Storm Ltd.
* @license {@link https://github.com/photonstorm/phaser/blob/master/license.txt|MIT License}
*/
var GetOverlapY = require('./GetOverlapY');
/**
* Separates two overlapping bodies on the Y-axis (vertically).
*
* Separation involves moving two overlapping bodies so they don't overlap anymore and adjusting their velocities based on their mass. This is a core part of collision detection.
*
* The bodies won't be separated if there is no vertical overlap between them, if they are static, or if either one uses custom logic for its separation.
*
* @function Phaser.Physics.Arcade.SeparateY
* @since 3.0.0
*
* @param {Phaser.Physics.Arcade.Body} body1 - The first Body to separate.
* @param {Phaser.Physics.Arcade.Body} body2 - The second Body to separate.
* @param {boolean} overlapOnly - If `true`, the bodies will only have their overlap data set and no separation will take place.
* @param {number} bias - A value to add to the delta value during overlap checking. Used to prevent sprite tunneling.
*
* @return {boolean} `true` if the two bodies overlap vertically, otherwise `false`.
*/
var SeparateY = function (body1, body2, overlapOnly, bias)
{
var overlap = GetOverlapY(body1, body2, overlapOnly, bias);
// Can't separate two immovable bodies, or a body with its own custom separation logic
if (overlapOnly || overlap === 0 || (body1.immovable && body2.immovable) || body1.customSeparateY || body2.customSeparateY)
{
// return true if there was some overlap, otherwise false
return (overlap !== 0) || (body1.embedded && body2.embedded);
}
// Adjust their positions and velocities accordingly (if there was any overlap)
var v1 = body1.velocity.y;
var v2 = body2.velocity.y;
if (!body1.immovable && !body2.immovable)
{
overlap *= 0.5;
body1.y -= overlap;
body2.y += overlap;
var nv1 = Math.sqrt((v2 * v2 * body2.mass) / body1.mass) * ((v2 > 0) ? 1 : -1);
var nv2 = Math.sqrt((v1 * v1 * body1.mass) / body2.mass) * ((v1 > 0) ? 1 : -1);
var avg = (nv1 + nv2) * 0.5;
nv1 -= avg;
nv2 -= avg;
body1.velocity.y = avg + nv1 * body1.bounce.y;
body2.velocity.y = avg + nv2 * body2.bounce.y;
}
else if (!body1.immovable)
{
body1.y -= overlap;
body1.velocity.y = v2 - v1 * body1.bounce.y;
// This is special case code that handles things like horizontal moving platforms you can ride
if (body2.moves)
{
body1.x += (body2.x - body2.prev.x) * body2.friction.x;
}
}
else
{
body2.y += overlap;
body2.velocity.y = v1 - v2 * body2.bounce.y;
// This is special case code that handles things like horizontal moving platforms you can ride
if (body1.moves)
{
body2.x += (body1.x - body1.prev.x) * body1.friction.x;
}
}
// If we got this far then there WAS overlap, and separation is complete, so return true
return true;
};
module.exports = SeparateY;