6 files changed, 75 insertions, 2 deletions
diff --git a/game/selectable.h b/game/selectable.h
new file mode 100644
index 0000000..c16246c
--- /dev/null
+++ b/game/selectable.h
@@ -0,0 +1,16 @@
+#ifndef SELECTABLE_H
+#define SELECTABLE_H
+
+#include <glm/glm.hpp>
+#include <special_members.hpp>
+
+class Selectable {
+public:
+	Selectable() = default;
+	virtual ~Selectable() = default;
+	DEFAULT_MOVE_COPY(Selectable);
+
+	[[nodiscard]] virtual bool intersectRay(const glm::vec3 &, const glm::vec3 &, glm::vec2 *, float *) const = 0;
+};
+
+#endif
diff --git a/game/vehicles/railVehicle.cpp b/game/vehicles/railVehicle.cpp
index aea7f8c..8d7b06f 100644
--- a/game/vehicles/railVehicle.cpp
+++ b/game/vehicles/railVehicle.cpp
@@ -1,8 +1,11 @@
 #include "railVehicle.h"
 #include "railVehicleClass.h"
 #include "train.h"
+#include <algorithm>
 #include <array>
 #include <glm/glm.hpp>
+#include <glm/gtx/intersect.hpp>
+#include <glm/gtx/transform.hpp>
 #include <location.hpp>
 #include <maths.h>
 #include <memory>
@@ -24,3 +27,44 @@ RailVehicle::move(const Train * t, float & trailBy)
 	location.rot = {vector_pitch(diff), vector_yaw(diff), 0};
 	trailBy += 0.6F + overhang;
 }
+
+bool
+RailVehicle::intersectRay(const glm::vec3 & pos, const glm::vec3 & dir, glm::vec2 * baryPos, float * eh) const
+{
+	constexpr const auto X = 1.35F;
+	const auto Y = this->rvClass->length / 2.F;
+	constexpr const auto Z = 3.9F;
+	const auto move = glm::translate(location.pos) * rotate_ypr(location.rot);
+	const std::array<glm::vec3, 8> cornerVertices {{
+			move * glm::vec4 {-X, Y, 0, 1}, //  LFB
+			move * glm::vec4 {X, Y, 0, 1}, //   RFB
+			move * glm::vec4 {-X, Y, Z, 1}, //  LFT
+			move * glm::vec4 {X, Y, Z, 1}, //   RFT
+			move * glm::vec4 {-X, -Y, 0, 1}, // LBB
+			move * glm::vec4 {X, -Y, 0, 1}, //  RBB
+			move * glm::vec4 {-X, -Y, Z, 1}, // LBT
+			move * glm::vec4 {X, -Y, Z, 1}, //  RBT
+	}};
+	static constexpr const std::array<glm::uvec3, 10> triangles {{
+			// Front
+			{0, 1, 2},
+			{1, 2, 3},
+			// Left
+			{0, 2, 4},
+			{2, 4, 6},
+			// Back
+			{4, 5, 6},
+			{5, 6, 7},
+			// Right
+			{1, 3, 5},
+			{3, 5, 7},
+			// Top
+			{2, 3, 6},
+			{3, 6, 7},
+	}};
+	return std::any_of(
+			triangles.begin(), triangles.end(), [&cornerVertices, &pos, &dir, &baryPos, &eh](const glm::uvec3 idx) {
+				return glm::intersectRayTriangle(pos, dir, cornerVertices[idx[0]], cornerVertices[idx[1]],
+						cornerVertices[idx[2]], *baryPos, *eh);
+			});
+}
diff --git a/game/vehicles/railVehicle.h b/game/vehicles/railVehicle.h
index a089f1d..55cb6a2 100644
--- a/game/vehicles/railVehicle.h
+++ b/game/vehicles/railVehicle.h
@@ -4,6 +4,8 @@
 #include "gfx/renderable.h"
 #include "railVehicleClass.h"
 #include <array>
+#include <game/selectable.h>
+#include <glm/glm.hpp>
 #include <location.hpp>
 #include <memory>
 #include <utility>
@@ -11,13 +13,14 @@
 class Shader;
 
 class Train;
-class RailVehicle : public Renderable {
+class RailVehicle : public Renderable, Selectable {
 public:
 	explicit RailVehicle(RailVehicleClassPtr rvc) : rvClass {std::move(rvc)} { }
 
 	void move(const Train *, float & trailBy);
 
 	void render(const Shader & shader) const override;
+	[[nodiscard]] bool intersectRay(const glm::vec3 &, const glm::vec3 &, glm::vec2 *, float *) const override;
 
 	Location location;
 
diff --git a/game/vehicles/train.cpp b/game/vehicles/train.cpp
index 14753c0..4f19bed 100644
--- a/game/vehicles/train.cpp
+++ b/game/vehicles/train.cpp
@@ -23,6 +23,12 @@ Train::getBogiePosition(float linkDist, float dist) const
 	return b2Link.first->positionAt(b2linkDist, b2Link.second);
 }
 
+bool
+Train::intersectRay(const glm::vec3 & pos, const glm::vec3 & dir, glm::vec2 * baryPos, float * eh) const
+{
+	return applyOne(&RailVehicle::intersectRay, pos, dir, baryPos, eh) != end();
+}
+
 void
 Train::tick(TickDuration dur)
 {
diff --git a/game/vehicles/train.h b/game/vehicles/train.h
index ef49209..c823aed 100644
--- a/game/vehicles/train.h
+++ b/game/vehicles/train.h
@@ -9,6 +9,7 @@
 #include "railVehicle.h"
 #include "vehicle.h"
 #include <collection.hpp>
+#include <glm/glm.hpp>
 #include <location.hpp>
 #include <memory>
 #include <vector>
@@ -27,6 +28,8 @@ public:
 
 	void render(const Shader & shader) const override;
 
+	[[nodiscard]] bool intersectRay(const glm::vec3 &, const glm::vec3 &, glm::vec2 *, float *) const override;
+
 	void tick(TickDuration elapsed) override;
 	void doActivity(Go *, TickDuration) override;
 	void doActivity(Idle *, TickDuration) override;
diff --git a/game/vehicles/vehicle.h b/game/vehicles/vehicle.h
index 07bd492..3ddeac5 100644
--- a/game/vehicles/vehicle.h
+++ b/game/vehicles/vehicle.h
@@ -6,13 +6,14 @@
 #include <game/activity.h>
 #include <game/network/link.h>
 #include <game/orders.h>
+#include <game/selectable.h>
 #include <game/worldobject.h>
 #include <gfx/renderable.h>
 #include <memory>
 
 class Location;
 
-class Vehicle : public WorldObject, public Renderable {
+class Vehicle : public WorldObject, public Renderable, public Selectable {
 public:
 	explicit Vehicle(const LinkPtr & link, float linkDist = 0);
 	float linkDist; // distance along current link