[Half-Life] Gargantua's Stomp attack is broken at higher framerates

[BlackShadow]

Gargantua's stomp attack is broken at higher framerates because his attack movement/velocity based on framerate.

As it can be seen here: https://streamable.com/uajuq

To fix this:

halflife/dlls/gargantua.cpp

Lines 146 to 148 in c7240b9

	// Accelerate the effect
	pev->speed = pev->speed + (gpGlobals->frametime) * pev->framerate;
	pev->framerate = pev->framerate + (gpGlobals->frametime) * 1500;

Change:

pev->framerate = pev->framerate + (gpGlobals->frametime) * 1500;

To:

pev->speed = pev->speed * 1.3;

[SamVanheer]

That doesn't really fix the problem. The attack speed will still be dependent on the framerate, just in a different way. Depending on the framerate the think method will execute more often since it can't execute exactly at the time set in pev->nextthink.

The proper way to fix this is to use the same solution as the turn rate fix (#2458).

After this line:

halflife/dlls/gargantua.cpp

Line 84 in c7240b9

static CStomp *StompCreate( const Vector &origin, const Vector &end, float speed );

Add this:

int		Save(CSave& save) override;
int		Restore(CRestore& restore) override;
static	TYPEDESCRIPTION m_SaveData[];

float m_flLastThinkTime;

After this line:

halflife/dlls/gargantua.cpp

Line 91 in c7240b9

LINK_ENTITY_TO_CLASS( garg_stomp, CStomp );

Add this:

TYPEDESCRIPTION	CStomp::m_SaveData[] =
{
	DEFINE_FIELD(CStomp, m_flLastThinkTime, FIELD_TIME),
};

IMPLEMENT_SAVERESTORE(CStomp, CBaseEntity);

Rework this code:

halflife/dlls/gargantua.cpp

Lines 124 to 148 in c7240b9

	TraceResult tr;
	pev->nextthink = gpGlobals->time + 0.1;
	// Do damage for this frame
	Vector vecStart = pev->origin;
	vecStart.z += 30;
	Vector vecEnd = vecStart + (pev->movedir * pev->speed * gpGlobals->frametime);
	UTIL_TraceHull( vecStart, vecEnd, dont_ignore_monsters, head_hull, ENT(pev), &tr );
	if ( tr.pHit && tr.pHit != pev->owner )
	{
	CBaseEntity *pEntity = CBaseEntity::Instance( tr.pHit );
	entvars_t *pevOwner = pev;
	if ( pev->owner )
	pevOwner = VARS(pev->owner);
	if ( pEntity )
	pEntity->TakeDamage( pev, pevOwner, gSkillData.gargantuaDmgStomp, DMG_SONIC );
	}
	// Accelerate the effect
	pev->speed = pev->speed + (gpGlobals->frametime) * pev->framerate;
	pev->framerate = pev->framerate + (gpGlobals->frametime) * 1500;

To this:

if (m_flLastThinkTime == 0)
{
	m_flLastThinkTime = gpGlobals->time - gpGlobals->frametime;
}

//Use 1/4th the delta time to match the original behavior more closely
const float deltaTime = (gpGlobals->time - m_flLastThinkTime) / 4;

m_flLastThinkTime = gpGlobals->time;

TraceResult tr;

pev->nextthink = gpGlobals->time + 0.1;

// Do damage for this frame
Vector vecStart = pev->origin;
vecStart.z += 30;
Vector vecEnd = vecStart + (pev->movedir * pev->speed * deltaTime);

UTIL_TraceHull( vecStart, vecEnd, dont_ignore_monsters, head_hull, ENT(pev), &tr );

if ( tr.pHit && tr.pHit != pev->owner )
{
	CBaseEntity *pEntity = CBaseEntity::Instance( tr.pHit );
	entvars_t *pevOwner = pev;
	if ( pev->owner )
		pevOwner = VARS(pev->owner);

	if ( pEntity )
		pEntity->TakeDamage( pev, pevOwner, gSkillData.gargantuaDmgStomp, DMG_SONIC );
}

// Accelerate the effect
pev->speed = pev->speed + deltaTime * pev->framerate;
pev->framerate = pev->framerate + deltaTime * 1500;

Instead of gpGlobals->frametime the code now uses the time between think method executions, which is the correct delta time. That time divided by 4 is a close enough match to the frametime at 30 FPS to consistently move the stomp at the same speed.