From de9909df038d1b6bb47bcc82fea5f8dc9dec2491 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Tue, 28 Dec 2021 15:42:50 +0000
Subject: Initial implementation for being able to click in the main window to
 select something

---
 game/vehicles/railVehicle.cpp | 44 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

(limited to 'game/vehicles/railVehicle.cpp')

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);
+			});
+}
-- 
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