HTML and CSS Reference
In-Depth Information
Reverse coordinate rotation
x1 = x * Math.cos(rotation) + y * Math.sin(rotation);
y1 = y * Math.cos(rotation) - x * Math.sin(rotation);
Chapter 11
Conservation of momentum, in straight mathematical terms
(m0 - m1) × v0 + 2 × m1 × v1
v0Final = ----------------------------
m0 + m1
(m1 - m0) × v1 + 2 × m0 × v0
v1Final = ----------------------------
m0 + m1
Conservation of momentum in JavaScript, with a shortcut
var vxTotal = vx0 - vx1;
vx0 = ((ball0.mass - ball1.mass) * vx0 + 2 * ball1.mass * vx1) / (ball0.mass + ball1.mass);
vx1 = vxTotal + vx0;
Chapter 12
Basic gravity
force = G
× m
1
× m
2
/ distance
2
JavaScript-friendly gravity implementation
function gravitate (partA, partB) {
var dx = partB.x - partA.x,
dy = partB.y - partA.y,
distSQ = dx * dx + dy * dy,
dist = Math.sqrt(distSQ),
force = partA.mass * partB.mass / distSQ,
ax = force * dx / dist,
ay = force * dy / dist;
partA.vx += ax / partA.mass;
partA.vy += ay / partA.mass;
partB.vx -= ax / partB.mass;
partB.vy -= ay / partB.mass;
}
