Collision Physics

Orbs collide elastically, transferring momentum and potentially triggering eliminations.

Collision Detection

Two orbs collide when their centers are closer than the sum of their radii:

fn check_collision(orb_a: &Orb, orb_b: &Orb) -> bool {
    let distance = (orb_a.position - orb_b.position).length();
    let min_distance = orb_a.radius + orb_b.radius;

    distance < min_distance
}

Collision Resolution

When orbs collide, velocities are exchanged along the collision axis:

fn resolve_collision(orb_a: &mut Orb, orb_b: &mut Orb, restitution: f32) {
    // Collision normal
    let normal = (orb_b.position - orb_a.position).normalize();

    // Relative velocity along normal
    let relative_velocity = orb_a.velocity - orb_b.velocity;
    let velocity_along_normal = relative_velocity.dot(normal);

    // Only resolve if approaching
    if velocity_along_normal > 0.0 {
        return;
    }

    // Calculate impulse (equal mass assumed)
    let impulse = -velocity_along_normal * restitution;

    // Apply impulse
    orb_a.velocity += normal * impulse;
    orb_b.velocity -= normal * impulse;

    // Separate overlapping orbs
    separate_orbs(orb_a, orb_b);
}

Configuration

Parameter	Description	Current Value
orbRestitution	Energy transfer coefficient	1.004

Restitution Effects

Value	Effect
< 1.0	Energy lost (dampening)
= 1.0	Energy preserved
> 1.0	Energy added (accelerating)

Current config (1.004) adds very slight energy, creating gradually faster gameplay.

Collision Events

Collisions can trigger:

Tether Breaking

If an orb is moving fast enough and hits a tether, the tether breaks.

Shockwaves

High-impact collisions emit shockwaves that can cut nearby tethers.

Eliminations

When all of a player's tethers are broken, they're eliminated.

Orb Properties

Property	Value	Description
radius	12px	Collision hitbox
baseSpeed	2.0	Initial velocity
colors	6	Visual distinction

Next Steps

• Tether System - Protective connections
• Sudden Death - Endgame mechanics
• Parameter Reference - All parameters