Method applyAccuracy

src/Battlescape/Projectile.cpp:245–326

* Calculates the new target in voxel space, based on the given accuracy modifier. * @param origin Startposition of the trajectory in voxels. * @param target Endpoint of the trajectory in voxels. * @param accuracy Accuracy modifier. * @param keepRange Whether range affects accuracy. * @param targetTile Tile of target. Default = 0. * @param extendLine should this line get extended to maximum d

 * @param extendLine should this line get extended to maximum distance?
 */
void Projectile::applyAccuracy(const Position& origin, Position *target, double accuracy, bool keepRange, Tile *targetTile, bool extendLine)
{
	int xdiff = origin.x - target->x;
	int ydiff = origin.y - target->y;
	double realDistance = sqrt((double)(xdiff*xdiff)+(double)(ydiff*ydiff));
	// maxRange is the maximum range a projectile shall ever travel in voxel space
	double maxRange = keepRange?realDistance:16*1000; // 1000 tiles
	maxRange = _action.type == BA_HIT?46:maxRange; // up to 2 tiles diagonally (as in the case of reaper v reaper)
	RuleItem *weapon = _action.weapon->getRules();

	if (_action.type != BA_THROW && _action.type != BA_HIT)
	{
		double modifier = 0.0;
		int upperLimit = weapon->getAimRange();
		int lowerLimit = weapon->getMinRange();
		if (Options::battleUFOExtenderAccuracy)
		{
			if (_action.type == BA_AUTOSHOT)
			{
				upperLimit = weapon->getAutoRange();
			}
			else if (_action.type == BA_SNAPSHOT)
			{
				upperLimit = weapon->getSnapRange();
			}
		}
		if (realDistance / 16 < lowerLimit)
		{
			modifier = (weapon->getDropoff() * (lowerLimit - realDistance / 16)) / 100;
		}
		else if (upperLimit < realDistance / 16)
		{
			modifier = (weapon->getDropoff() * (realDistance / 16 - upperLimit)) / 100;
		}
		accuracy = std::max(0.0, accuracy - modifier);
	}

	int xDist = abs(origin.x - target->x);
	int yDist = abs(origin.y - target->y);
	int zDist = abs(origin.z - target->z);
	int xyShift, zShift;

	if (xDist / 2 <= yDist)				//yes, we need to add some x/y non-uniformity
		xyShift = xDist / 4 + yDist;	//and don't ask why, please. it's The Commandment
	else
		xyShift = (xDist + yDist) / 2;	//that's uniform part of spreading

	if (xyShift <= zDist)				//slight z deviation
		zShift = xyShift / 2 + zDist;
	else
		zShift = xyShift + zDist / 2;

	int deviation = RNG::generate(0, 100) - (accuracy * 100);

	if (deviation >= 0)
		deviation += 50;				// add extra spread to "miss" cloud
	else
		deviation += 10;				//accuracy of 109 or greater will become 1 (tightest spread)