Fixed inaccurate emitter impulse estimation, causing severe AI problems with certain actors

Author: Causeless

Source/Entities/AEmitter.cpp

@@ -271,32 +271,39 @@ float AEmitter::EstimateImpulse(bool burst) {
 	// Calculate the impulse generated by the emissions, once and store the result
 	if ((!burst && m_AvgImpulse < 0) || (burst && m_AvgBurstImpulse < 0)) {
 		float impulse = 0.0F;
-		float velMin, velMax, velRange, spread;
 
 		// Go through all emissions and emit them according to their respective rates
 		for (Emission* emission: m_EmissionList) {
 			// Only check emissions that push the emitter
 			if (emission->PushesEmitter()) {
+				// Todo... we're not checking emission start/stop times here, so this will always calculate the impulse as if the emission was active.
+				// There's not really an easy way to do this, since the emission rate is not necessarily constant over time.
 				float emissions = (emission->GetRate() / 60.0f) * g_TimerMan.GetDeltaTimeSecs();
 				float scale = 1.0F;
 				if (burst) {
 					emissions *= emission->GetBurstSize();
 					scale = m_BurstScale;
 				}
 
-				velMin = emission->GetMinVelocity() * scale;
-				velRange = (emission->GetMaxVelocity() - emission->GetMinVelocity()) * 0.5F * scale;
-				spread = (std::max(static_cast<float>(c_PI) - emission->GetSpread(), 0.0F) / c_PI) * scale; // A large spread will cause the forces to cancel eachother out
+				if (emissions > 0) {
+				    int extraEmissions = emission->GetParticleCount() - 1;
+				    emissions += extraEmissions;
+			    }
+
+				float velMin = emission->GetMinVelocity() * scale;
+			    float velRange = (emission->GetMaxVelocity() - emission->GetMinVelocity()) * scale * 0.5f;
+			    float spread = (std::max(static_cast<float>(c_PI) - (emission->GetSpread() * scale), 0.0F) / c_PI); // A large spread will cause the forces to cancel eachother out
 
 				// Add to accumulative recoil impulse generated, F = m * a.
 				impulse += (velMin + velRange) * spread * emission->m_pEmission->GetMass() * emissions;
 			}
 		}
 
-		if (burst)
+		if (burst) {
 			m_AvgBurstImpulse = impulse;
-		else
+		} else {
 			m_AvgImpulse = impulse;
+		}
 	}
 
 	// Scale the emission rate up or down according to the appropriate throttle multiplier.
@@ -411,9 +418,10 @@ void AEmitter::Update() {
 			// Start timing until next burst
 			m_BurstTimer.Reset();
 		}
-		// Not enough spacing, cancel the triggering if there was any
-		else
+		else {
+			// Not enough spacing, cancel the triggering if there was any
 			m_BurstTriggered = false;
+		}
 
 		int emissionCountTotal = 0;
 		float velMin, velRange, spread;
@@ -448,7 +456,7 @@ void AEmitter::Update() {
 				float scale = 1.0F;
 				// Add extra emissions if bursting.
 				if (m_BurstTriggered) {
-					emissionCount += emission->GetBurstSize() * std::floor(throttleFactor);
+					emissionCount += emission->GetBurstSize();
 					scale = m_BurstScale;
 				}
 				emissionCountTotal += emissionCount;
@@ -515,7 +523,14 @@ void AEmitter::Update() {
 		m_LastEmitTmr.Reset();
 
 		// Apply recoil/push effects. Joint stiffness will take effect when these are transferred to the parent.
-		if (!pushImpulses.IsZero()) {
+		static bool enableFakedImpulse = false; // useful for debugging the accuracy of EstimateImpulse();
+		if (enableFakedImpulse) {
+			Vector fakeImpulse;
+			fakeImpulse.SetXY(-EstimateImpulse(m_BurstTriggered), 0.0F);
+			fakeImpulse.RadRotate(m_EmitAngle.GetRadAngle());
+			fakeImpulse = RotateOffset(fakeImpulse);
+			AddImpulseForce(fakeImpulse);
+		} else {
 			AddImpulseForce(pushImpulses);
 		}
 

Source/Entities/MovableObject.cpp

@@ -728,10 +728,13 @@ void MovableObject::AddAbsForce(const Vector& force, const Vector& absPos) {
 }
 
 void MovableObject::AddAbsImpulseForce(const Vector& impulse, const Vector& absPos) {
+	if (impulse.IsZero()) {
+		return;
+	}
+
 #ifndef RELEASE_BUILD
 	RTEAssert(impulse.GetLargest() < 500000, "HUEG IMPULSE FORCE");
 #endif
-
 	m_ImpulseForces.push_back(std::make_pair(impulse, g_SceneMan.ShortestDistance(m_Pos, absPos) * c_MPP));
 }
 

Source/Entities/MovableObject.h

@@ -628,12 +628,14 @@ namespace RTE {
 		/// @param offset A Vector with the offset, in METERS, of where the impulse is being (default: Vector())
 		/// applied relative to the center of this MovableObject.
 		void AddImpulseForce(const Vector& impulse, const Vector& offset = Vector()) {
+			if (impulse.IsZero()) {
+				return;
+			}
 
 #ifndef RELEASE_BUILD
 			RTEAssert(impulse.MagnitudeIsLessThan(500000.0F), "HUEG IMPULSE FORCE");
 			RTEAssert(offset.MagnitudeIsLessThan(5000.0F), "HUGE IMPULSE FORCE OFFSET");
 #endif
-
 			m_ImpulseForces.push_back({impulse, offset});
 		}
 

Source/Entities/PEmitter.cpp

@@ -227,39 +227,47 @@ float PEmitter::EstimateImpulse(bool burst) {
 	// Calculate the impulse generated by the emissions, once and store the result
 	if ((!burst && m_AvgImpulse < 0) || (burst && m_AvgBurstImpulse < 0)) {
 		float impulse = 0.0F;
-		float velMin, velMax, velRange, spread;
 
 		// Go through all emissions and emit them according to their respective rates
 		for (Emission* emission: m_EmissionList) {
 			// Only check emissions that push the emitter
 			if (emission->PushesEmitter()) {
+				// Todo... we're not checking emission start/stop times here, so this will always calculate the impulse as if the emission was active.
+				// There's not really an easy way to do this, since the emission rate is not necessarily constant over time.
 				float emissions = (emission->GetRate() / 60.0f) * g_TimerMan.GetDeltaTimeSecs();
 				float scale = 1.0F;
 				if (burst) {
 					emissions *= emission->GetBurstSize();
 					scale = m_BurstScale;
 				}
 
-				velMin = emission->GetMinVelocity() * scale;
-				velRange = (emission->GetMaxVelocity() - emission->GetMinVelocity()) * 0.5F * scale;
-				spread = (std::max(static_cast<float>(c_PI) - emission->GetSpread(), 0.0F) / c_PI) * scale; // A large spread will cause the forces to cancel eachother out
+				if (emissions > 0) {
+					int extraEmissions = emission->GetParticleCount() - 1;
+					emissions += extraEmissions;
+				}
+
+				float velMin = emission->GetMinVelocity() * scale;
+				float velRange = (emission->GetMaxVelocity() - emission->GetMinVelocity()) * scale * 0.5f;
+				float spread = (std::max(static_cast<float>(c_PI) - (emission->GetSpread() * scale), 0.0F) / c_PI); // A large spread will cause the forces to cancel eachother out
 
 				// Add to accumulative recoil impulse generated, F = m * a.
 				impulse += (velMin + velRange) * spread * emission->m_pEmission->GetMass() * emissions;
 			}
 		}
 
-		if (burst)
+		if (burst) {
 			m_AvgBurstImpulse = impulse;
-		else
+		} else {
 			m_AvgImpulse = impulse;
+		}
 	}
 
 	// Scale the emission rate up or down according to the appropriate throttle multiplier.
 	float throttleFactor = GetThrottleFactor();
 	// Apply the throttle factor to the emission rate per update
-	if (burst)
+	if (burst) {
 		return m_AvgBurstImpulse * throttleFactor;
+	}
 
 	return m_AvgImpulse * throttleFactor;
 }