Fixed Thing_ProjectileAimed being broken.

- It was calling the fallback aiming in the wrong place when it should have been outside the speed check.
- Credit to _mental_ for the base code, but no gotos involved.

src/p_things.cpp

@@ -163,16 +163,30 @@ bool P_Thing_Move (int tid, AActor *source, int mapspot, bool fog)
 	return false;
 }
 
+//==========================================================================
+//
+// VelIntercept
+//
+//==========================================================================
+
+void InterceptDefaultAim(AActor *mobj, AActor *targ, DVector3 aim, double speed)
+{
+	if (mobj == nullptr || targ == nullptr)	return;
+	mobj->Angles.Yaw = mobj->AngleTo(targ);
+	mobj->Vel = aim.Resized(speed);
+}
+
 // [MC] Was part of P_Thing_Projectile, now its own function for use in ZScript.
 // Aims mobj at targ based on speed and targ's velocity.
-void VelIntercept(AActor *targ, AActor *mobj, double speed, bool aimpitch = false, bool oldvel = false)
+static void VelIntercept(AActor *targ, AActor *mobj, double speed, bool aimpitch = false, bool oldvel = false, bool leadtarget = true)
 {
 	if (targ == nullptr || mobj == nullptr)	return;
 
-	if (speed > 0 && !targ->Vel.isZero())
+	DVector3 aim = mobj->Vec3To(targ);
+	aim.Z += targ->Height / 2;
+
+	if (leadtarget && speed > 0 && !targ->Vel.isZero())
 	{
-		DVector3 aim = mobj->Vec3To(targ);
-		aim.Z += targ->Height / 2;
 		// Aiming at the target's position some time in the future
 		// is basically just an application of the law of sines:
 		//     a/sin(A) = b/sin(B)
@@ -180,7 +194,6 @@ void VelIntercept(AActor *targ, AActor *mobj, double speed, bool aimpitch = fals
 		// with the math. I don't think I would have thought of using
 		// trig alone had I been left to solve it by myself.
 
-		bool nolead = false;
 		DVector3 tvel = targ->Vel;
 		if (!(targ->flags & MF_NOGRAVITY) && targ->waterlevel < 3)
 		{ // If the target is subject to gravity and not underwater,
@@ -188,45 +201,46 @@ void VelIntercept(AActor *targ, AActor *mobj, double speed, bool aimpitch = fals
 		  // even if we did consider the vertical component of the target's
 		  // velocity, we would still miss more often than not.
 			tvel.Z = 0.0;
-			nolead = !!(targ->Vel.X == 0 && targ->Vel.Y == 0);
+
-		}
+			if (targ->Vel.X == 0 && targ->Vel.Y == 0)
-		if (!nolead)
-		{
-			double dist = aim.Length();
-			double targspeed = tvel.Length();
-			double ydotx = -aim | tvel;
-			double a = g_acos(clamp(ydotx / targspeed / dist, -1.0, 1.0));
-			double multiplier = double(pr_leadtarget.Random2())*0.1 / 255 + 1.1;
-			double sinb = -clamp(targspeed*multiplier * g_sin(a) / speed, -1.0, 1.0);
-			DVector3 prevel = mobj->Vel;
-			// Use the cross product of two of the triangle's sides to get a
-			// rotation vector.
-			DVector3 rv(tvel ^ aim);
-			// The vector must be normalized.
-			rv.MakeUnit();
-			// Now combine the rotation vector with angle b to get a rotation matrix.
-			DMatrix3x3 rm(rv, g_cos(g_asin(sinb)), sinb);
-			// And multiply the original aim vector with the matrix to get a
-			// new aim vector that leads the target.
-			DVector3 aimvec = rm * aim;
-			// And make the projectile follow that vector at the desired speed.
-			mobj->Vel = aimvec * (speed / dist);
-			mobj->AngleFromVel();
-			if (oldvel)
 			{
-				mobj->Vel = prevel;
+				InterceptDefaultAim(mobj, targ, aim, speed);
-			}
+				return;
-			if (aimpitch) // [MC] Ripped right out of A_FaceMovementDirection
-			{
-				const DVector2 velocity = mobj->Vel.XY();
-				mobj->Angles.Pitch = -VecToAngle(velocity.Length(), mobj->Vel.Z);
 			}
 		}
-		else
+		double dist = aim.Length();
+		double targspeed = tvel.Length();
+		double ydotx = -aim | tvel;
+		double a = g_acos(clamp(ydotx / targspeed / dist, -1.0, 1.0));
+		double multiplier = double(pr_leadtarget.Random2())*0.1 / 255 + 1.1;
+		double sinb = -clamp(targspeed*multiplier * g_sin(a) / speed, -1.0, 1.0);
+		DVector3 prevel = mobj->Vel;
+		// Use the cross product of two of the triangle's sides to get a
+		// rotation vector.
+		DVector3 rv(tvel ^ aim);
+		// The vector must be normalized.
+		rv.MakeUnit();
+		// Now combine the rotation vector with angle b to get a rotation matrix.
+		DMatrix3x3 rm(rv, g_cos(g_asin(sinb)), sinb);
+		// And multiply the original aim vector with the matrix to get a
+		// new aim vector that leads the target.
+		DVector3 aimvec = rm * aim;
+		// And make the projectile follow that vector at the desired speed.
+		mobj->Vel = aimvec * (speed / dist);
+		mobj->AngleFromVel();
+		if (oldvel)
 		{
-			mobj->Angles.Yaw = mobj->AngleTo(targ);
+			mobj->Vel = prevel;
-			mobj->Vel = aim.Resized(speed);
 		}
+		if (aimpitch) // [MC] Ripped right out of A_FaceMovementDirection
+		{
+			const DVector2 velocity = mobj->Vel.XY();
+			mobj->Angles.Pitch = -VecToAngle(velocity.Length(), mobj->Vel.Z);
+		}
+	}
+	else
+	{
+		InterceptDefaultAim(mobj, targ, aim, speed);
 	}
 }
 
@@ -325,10 +339,8 @@ bool P_Thing_Projectile (int tid, AActor *source, int type, const char *type_nam
 
 					if (targ != nullptr)
 					{
-						if (leadTarget)
+						VelIntercept(targ, mobj, speed, false, false, leadTarget);
-						{
+
-							VelIntercept(targ, mobj, speed);
-						}
 						if (mobj->flags2 & MF2_SEEKERMISSILE)
 						{
 							mobj->tracer = targ;