C++ DVector3::Resized方法代码示例

//.........这里部分代码省略.........
						if (leadTarget && speed > 0 && !targ->Vel.isZero())
						{
							// 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)
							// Thanks to all those on the notgod phorum for helping me
							// with the math. I don't think I would have thought of using
							// trig alone had I been left to solve it by myself.

							DVector3 tvel = targ->Vel;
							if (!(targ->flags & MF_NOGRAVITY) && targ->waterlevel < 3)
							{ // If the target is subject to gravity and not underwater,
							  // assume that it isn't moving vertically. Thanks to gravity,
							  // 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;
								if (targ->Vel.X == 0 && targ->Vel.Y == 0)
								{
									goto 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);

							// 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();
						}
						else
						{
nolead:
							mobj->Angles.Yaw = mobj->AngleTo(targ);
							mobj->Vel = aim.Resized (speed);
						}
						if (mobj->flags2 & MF2_SEEKERMISSILE)
						{
							mobj->tracer = targ;
						}
					}
					else
					{
						mobj->Angles.Yaw = angle;
						mobj->VelFromAngle(speed);
						mobj->Vel.Z = vspeed;
					}
					// Set the missile's speed to reflect the speed it was spawned at.
					if (mobj->flags & MF_MISSILE)
					{
						mobj->Speed = mobj->VelToSpeed();
					}
					// Hugger missiles don't have any vertical velocity
					if (mobj->flags3 & (MF3_FLOORHUGGER|MF3_CEILINGHUGGER))
					{
						mobj->Vel.Z = 0;
					}
					if (mobj->flags & MF_SPECIAL)
					{
						mobj->flags |= MF_DROPPED;
					}
					if (mobj->flags & MF_MISSILE)
					{
						if (P_CheckMissileSpawn (mobj, spot->radius))
						{
							rtn = true;
						}
					}
					else if (!P_TestMobjLocation (mobj))
					{
						// If this is a monster, subtract it from the total monster
						// count, because it already added to it during spawning.
						mobj->ClearCounters();
						mobj->Destroy ();
					}
					else
					{
						// It spawned fine.
						rtn = 1;
					}
				}
			} while (dest != 0 && (targ = tit.Next()));
		}
		spot = iterator.Next();
	}

	return rtn != 0;
}

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);
}