Repulsion force that pushes overlapping objects apart to prevent interpenetration.

Overlap Resolution: Push objects apart when they overlap to prevent interpenetration.

Continuous Application: Forces applied every frame while objects remain overlapping.

Mass-Based Response: Force produces different accelerations based on object mass.

Repulsion: Objects push apart when overlapping, with force directed away from collision point.

Overlap-Based Magnitude: Force magnitude increases with overlap amount (closer = stronger repulsion).

Mass Influence: Force applied to both objects, with acceleration inversely proportional to mass (F = ma).

Breaking Threshold: When objects get very close (distance < d), combination mechanic triggers instead of force application.

Range: Operates within two-layer hexagonal neighborhood (sqrt(7)d/2 - d maximum distance).

⚠️ NEEDS SPECIFICATION: Exact collision force formula TBD through playtesting.

Considerations:

Expected Behavior:

Pairwise Forces: Calculate collision force for each overlapping neighbor independently.

Vector Addition: All collision forces summed together for net repulsion.

Symmetric Application: Each object in collision pair experiences force (Newton's third law).

Acceleration: a = F/m determines how much each object moves in response to collision.

Momentum Transfer: Lighter objects accelerate more than heavier objects from same force.

Realistic Response: Mass-based physics creates intuitive collision behavior.

See Movement System for mass properties and velocity updates.

Distance Threshold: When objects closer than combination distance d, merging takes over.

Force Cutoff: Collision forces stop applying at very close range (handled by combination instead).

Transition: Smooth transition from force-based separation to combination-based merging.

See Object Merging for combination mechanics.

Opposing Forces: Collision (repulsion) must overcome cohesion (attraction) for objects to separate.

Stable Equilibrium: Forces should balance to maintain object spacing without oscillation.

Dominance: Collision forces typically stronger at close range than cohesion at same distance.

See Cohesion for attraction force mechanics.

Determinism: All calculations use fixed-point arithmetic for cross-platform consistency.

Precision: Distance and force calculations use 16.16 fixed-point format.

Overflow Prevention: Force magnitude clamped to prevent fixed-point overflow in extreme cases.

See cross-referenceDeterminism for fixed-point implementation details.

Pass Integration: Collision forces calculated in "Apply Forces + Move" GPU pass.

Neighborhood Caching: Two-layer hex neighborhood loaded into workgroup shared memory.

Parallel Processing: Each object independently calculates collision forces from neighbors.

See Pipeline Passes for integration with multi-pass GPU execution.

Neighbor Limits: Two-layer range constraint keeps collision calculations bounded.

Early Termination: Skip collision calculations for stationary objects with no nearby motion.

Shared Memory: Workgroup caching minimizes texture reads for neighbor data.

Playtesting Required: Collision formula will be refined through gameplay iteration.

Adjustable Parameters: Force strength and response curve exposed as configuration values.

Gameplay Feel: Balance between realistic physics response and responsive, fun gameplay.