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Take dt into account for gravity calculations

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This commit is contained in:
Cameron Foale
2013-12-17 14:38:44 +11:00
parent 388e42c80a
commit b8dbb5d125
1 changed files with 18 additions and 19 deletions
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src/physics/arcade/ArcadePhysics.js
+18 -19
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@@ -172,19 +172,29 @@ Phaser.Physics.Arcade.prototype = {
// If you're wondering why the velocity is halved and applied twice, read this: http://www.niksula.hut.fi/~hkankaan/Homepages/gravity.html
// Rotation
this._velocityDelta = (this.computeVelocity(0, body, body.angularVelocity, body.angularAcceleration, body.angularDrag, body.maxAngular) - body.angularVelocity) * 0.5;
this._velocityDelta = (this.computeVelocity(body, body.angularVelocity, body.angularAcceleration, body.angularDrag, body.maxAngular, 0) - body.angularVelocity) * 0.5;
body.angularVelocity += this._velocityDelta;
body.rotation += (body.angularVelocity * this.game.time.physicsElapsed);
body.angularVelocity += this._velocityDelta;
if(body.allowGravity)
{
// Gravity was previously applied without taking physicsElapsed into account
// so it needs to be multiplied by 60 (fps) for compatibility with existing games
this._gravityX = (this.gravity.x + body.gravity.x) * 60;
this._gravityY = (this.gravity.y + body.gravity.y) * 60;
} else {
this._gravityX = this._gravityY = 0;
}
// Horizontal
this._velocityDelta = (this.computeVelocity(1, body, body.velocity.x, body.acceleration.x, body.drag.x, body.maxVelocity.x) - body.velocity.x) * 0.5;
this._velocityDelta = (this.computeVelocity(body, body.velocity.x, body.acceleration.x, body.drag.x, body.maxVelocity.x, this._gravityX) - body.velocity.x) * 0.5;
body.velocity.x += this._velocityDelta;
body.x += (body.velocity.x * this.game.time.physicsElapsed);
body.velocity.x += this._velocityDelta;
// Vertical
this._velocityDelta = (this.computeVelocity(2, body, body.velocity.y, body.acceleration.y, body.drag.y, body.maxVelocity.y) - body.velocity.y) * 0.5;
this._velocityDelta = (this.computeVelocity(body, body.velocity.y, body.acceleration.y, body.drag.y, body.maxVelocity.y, this._gravityY) - body.velocity.y) * 0.5;
body.velocity.y += this._velocityDelta;
body.y += (body.velocity.y * this.game.time.physicsElapsed);
body.velocity.y += this._velocityDelta;
@@ -195,32 +205,21 @@ Phaser.Physics.Arcade.prototype = {
* A tween-like function that takes a starting velocity and some other factors and returns an altered velocity.
*
* @method Phaser.Physics.Arcade#computeVelocity
* @param {number} axis - 1 for horizontal, 2 for vertical.
* @param {Phaser.Physics.Arcade.Body} body - The Body object to be updated.
* @param {number} velocity - Any component of velocity (e.g. 20).
* @param {number} acceleration - Rate at which the velocity is changing.
* @param {number} drag - Really kind of a deceleration, this is how much the velocity changes if Acceleration is not set.
* @param {number} [max=10000] - An absolute value cap for the velocity.
* @param {number} gravity - The acceleration due to gravity. Gravity will not induce drag.
* @return {number} The altered Velocity value.
*/
computeVelocity: function (axis, body, velocity, acceleration, drag, max) {
computeVelocity: function (body, velocity, acceleration, drag, max, gravity) {
max = max || 10000;
if (axis == 1 && body.allowGravity)
{
velocity += this.gravity.x + body.gravity.x;
}
else if (axis == 2 && body.allowGravity)
{
velocity += this.gravity.y + body.gravity.y;
}
if (acceleration !== 0)
{
velocity += acceleration * this.game.time.physicsElapsed;
}
else if (drag !== 0)
velocity += (acceleration + gravity) * this.game.time.physicsElapsed;
if (acceleration === 0 && drag !== 0)
{
this._drag = drag * this.game.time.physicsElapsed;