attack-induced spring not removed on attacker death

[drbergman]

Issue:
Spring attachments are generally not cleared when a death model starts. In most cases, this behavior is appropriate — we don’t want to automatically remove all spring connections.

However, attack-induced springs are a special case. When an attacker begins its death model, the spring connecting it to the attackee should be removed. Currently, this does not happen, leaving the attacker still “attached” after death.

By contrast, the spring is already handled correctly when the attackee dies — it’s removed as expected.

Proposed fix:
Ensure that attack-induced springs are explicitly removed when the attacker begins its death model.

[drbergman]

By contrast, the spring is already handled correctly when the attackee dies — it’s removed as expected.

Expanding on this for my own clarity: it is removed because the attacker sees the attackee is dead in the next standard_cell_cell_interactions block. Pseudocode:

if Target is dead:
	end_attack( this , Target );

Full code:

PhysiCell/core/PhysiCell_standard_models.cpp

Lines 1334 to 1348 in 69a23db

	if( UniformRandom() < probability || pTarget->phenotype.death.dead )
	{
	/*
	std::cout << "********* ********* ******** attack done **** " << PhysiCell_globals.current_time << " "
	<< probability << " "
	<< "attack time: " << pTarget->state.total_attack_time << " "
	<< "damage: " << pTarget->phenotype.cell_integrity.damage << " "
	<< "dead? " << (int) pTarget->phenotype.death.dead << " "
	<< "damage delivered: " << pCell->phenotype.cell_interactions.total_damage_delivered << std::endl;
	*/
	detach_cells_as_spring(pCell,pTarget);
	pCell->phenotype.cell_interactions.pAttackTarget = NULL;
	}