Function DoProjectileDynamics

TombEngine/Game/collision/collide_item.cpp:1294–1810

NOTE: Previously DoProperDetection().

// NOTE: Previously DoProperDetection().
void DoProjectileDynamics(short itemNumber, int x, int y, int z, int xv, int yv, int zv)
{
	auto* item = &g_Level.Items[itemNumber];

	auto prevPointColl = GetPointCollision(Vector3i(x, y, z), item->RoomNumber);
	auto pointColl = GetPointCollision(*item);

	// TODO: Use floor normal directly.
	auto floorTilt = GetSurfaceTilt(pointColl.GetFloorNormal(), true);

	auto bounds = GameBoundingBox(item);
	int radius = bounds.GetHeight();

	item->Pose.Position.y += radius;

	if (item->Pose.Position.y >= pointColl.GetFloorHeight())
	{
		int bs = 0;

		if (pointColl.IsSteepFloor() && prevPointColl.GetFloorHeight() < pointColl.GetFloorHeight())
		{
			int yAngle = (long)((unsigned short)item->Pose.Orientation.y);

			if (floorTilt.x < 0)
			{
				if (yAngle >= ANGLE(180.0f))
					bs = 1;
			}
			else if (floorTilt.x > 0)
			{
				if (yAngle <= ANGLE(180.0f))
					bs = 1;
			}

			if (floorTilt.y < 0)
			{
				if (yAngle >= ANGLE(90.0f) && yAngle <= ANGLE(270.0f))
					bs = 1;
			}
			else if (floorTilt.y > 0)
			{
				if (yAngle <= ANGLE(90.0f) || yAngle >= ANGLE(270.0f))
					bs = 1;
			}
		}

		// If last position of item was also below this floor height, we've hit a wall, else we've hit a floor.

		if (y > (pointColl.GetFloorHeight() + 32) && bs == 0 &&
			(((x / BLOCK(1)) != (item->Pose.Position.x / BLOCK(1))) ||
				((z / BLOCK(1)) != (item->Pose.Position.z / BLOCK(1)))))
		{
			// Need to know which direction the wall is.

			long xs;

			if ((x & (~WALL_MASK)) != (item->Pose.Position.x & (~WALL_MASK)) &&	// X crossed boundary?
				(z & (~WALL_MASK)) != (item->Pose.Position.z & (~WALL_MASK)))	// Z crossed boundary as well?