electrical arc upgrade, stage 4: add a new ModifyElectricArcPoints fu…

…nction with a handy valueToVec3d utility function

code/scripting/api/objs/ship.cpp

@@ -36,6 +36,9 @@
 #include "ship/shipfx.h"
 #include "ship/shiphit.h"
 
+#include "scripting/lua/LuaException.h"
+#include "scripting/lua/LuaUtil.h"
+
 extern void ship_reset_disabled_physics(object *objp, int ship_class);
 extern bool sexp_check_flag_arrays(const char *flag_name, Object::Object_Flags &object_flag, Ship::Ship_Flags &ship_flags, Mission::Parse_Object_Flags &parse_obj_flag, AI::AI_Flags &ai_flag);
 extern void sexp_alter_ship_flag_helper(object_ship_wing_point_team &oswpt, bool future_ships, Object::Object_Flags object_flag, Ship::Ship_Flags ship_flag, Mission::Parse_Object_Flags parse_obj_flag, AI::AI_Flags ai_flag, bool set_flag);
@@ -2824,5 +2827,68 @@ ADE_FUNC(ModifyElectricArc, l_Ship, "number index, vector firstPoint, vector sec
 	return ADE_RETURN_NIL;
 }
 
+ADE_FUNC(ModifyElectricArcPoints, l_Ship, "number index, table points, [number width]",
+	"Sets the collection of persistent points to be used by this arc, as well as optionally the arc's width.  "
+		"The table of points should consist of Vectors (e.g. created with ba.createVector()), arrays with three elements each, or tables with 'x'/'X', 'y'/'Y', and 'z'/'Z' pairs.  There must be at least two points.",
+	nullptr,
+	nullptr)
+{
+	object_h* objh = nullptr;
+	int index;
+	luacpp::LuaTable luaPoints;
+	float width = 0.0f;
+
+	int args = ade_get_args(L, "oit|f", l_Ship.GetPtr(&objh), &index, &luaPoints, &width);
+	if (args < 3)
+		return ADE_RETURN_NIL;
+
+	if (!objh->isValid())
+		return ADE_RETURN_NIL;
+
+	auto shipp = &Ships[objh->objp()->instance];
+
+	index--;	// Lua -> FS2
+	if (SCP_vector_inbounds(shipp->electrical_arcs, index) && luaPoints.isValid())
+	{
+		SCP_vector<vec3d> fsoPoints;
+
+		// convert Lua points to FSO points
+		for (const auto &entry : luaPoints)
+		{
+			try
+			{
+				fsoPoints.push_back(luacpp::util::valueToVec3d(entry.second));
+			}
+			catch (const luacpp::LuaException &e)
+			{
+				LuaError(L, "%s", e.what());
+				return ADE_RETURN_NIL;
+			}
+		}
+
+		if (fsoPoints.size() < 2)
+		{
+			LuaError(L, "Points table passed to ship:ModifyElectricArcPoints() has fewer than two points!");
+			return ADE_RETURN_NIL;
+		}
+
+		auto &arc = shipp->electrical_arcs[index];
+		arc.endpoint_1 = fsoPoints.front();
+		arc.endpoint_2 = fsoPoints.back();
+
+		// need to create the persistent point storage if it isn't set up yet
+		if (!arc.persistent_arc_points)
+			arc.persistent_arc_points.reset(new SCP_vector<vec3d>());
+
+		// assign all of our new points to the persistent point storage
+		arc.persistent_arc_points->operator=(std::move(fsoPoints));
+
+		if (args >= 4)
+			arc.width = width;
+	}
+
+	return ADE_RETURN_NIL;
+}
+
 }
 }

code/scripting/lua/LuaUtil.cpp

@@ -1,6 +1,8 @@
 
 #include "LuaUtil.h"
 
+#include "scripting/api/objs/vecmath.h"
+
 namespace {
 const char* mainStateRefName = "_lua_mainthread";
 }
@@ -62,5 +64,81 @@ lua_State* getMainThread(lua_State* L)
 	return state;
 }
 
+vec3d valueToVec3d(const LuaValue &luaValue)
+{
+	if (luaValue.is(luacpp::ValueType::TABLE))
+	{
+		vec3d tablePoint = vmd_zero_vector;
+		int index = 0;
+		bool is_array = false;
+		bool is_table = false;
+
+		// we have to go deeper
+		luacpp::LuaTable childTable;
+		childTable.setReference(luaValue.getReference());
+		for (const auto &childEntry : childTable)
+		{
+			// note: this is pre-increment
+			if (index >= 3)
+				throw LuaException("Vec3d table has more than three entries!");
+
+			if (!childEntry.second.is(luacpp::ValueType::NUMBER))
+				throw LuaException("Value in vec3d table is not a number!");
+
+			auto number = static_cast<float>(childEntry.second.getValue<double>());
+
+			if (childEntry.first.is(luacpp::ValueType::STRING))
+			{
+				is_table = true;
+				if (is_array)
+					throw LuaException("Vec3d table has an unexpected format!");
+
+				const auto &str = childEntry.first.getValue<SCP_string>();
+				if (lcase_equal(str, "x"))
+					tablePoint.xyz.x = number;
+				else if (lcase_equal(str, "y"))
+					tablePoint.xyz.y = number;
+				else if (lcase_equal(str, "z"))
+					tablePoint.xyz.z = number;
+				else
+					throw LuaException("Vec3d table has an entry other than x/X, y/Y, or z/Z!");
+			}
+			else
+			{
+				is_array = true;
+				if (is_table)
+					throw LuaException("Vec3d table has an unexpected format!");
+
+				tablePoint.a1d[index] = number;
+			}
+
+			index++;
+		}
+
+		// note: this is post-increment
+		if (index < 3)
+			throw LuaException("Vec3d table has fewer than three entries!");
+
+		return tablePoint;
+	}
+	else if (luaValue.is(luacpp::ValueType::USERDATA))
+	{
+		try
+		{
+			vec3d v;
+			luaValue.getValue(scripting::api::l_Vector.Get(&v));
+			return v;
+		}
+		catch (const luacpp::LuaException& /*e*/)
+		{
+			throw LuaException("Userdata in vec3d table is not a vector!");
+		}
+	}
+	else
+	{
+		throw LuaException("Vec3d value is of an unhandled type!");
+	}
+}
+
 } // namespace util
 } // namespace luacpp

code/scripting/lua/LuaUtil.h

@@ -91,6 +91,14 @@ void tableToList(LuaTable& table, Container& list) {
 }
 
 const char* getValueName(ValueType type);
+
+/**
+ * Processes a LuaValue and returns a vec3d.  The LuaValue could be a Vector, an array with three elements, or a table with x/X, y/Y, and z/Z entries.
+ * 
+ * Throws a LuaException if the conversion was not successful.
+ */
+vec3d valueToVec3d(const LuaValue &luaValue);
+
 }
 }