From f8762cc2c689fc11c3c8e9927f0dd3a2b6650d77 Mon Sep 17 00:00:00 2001
From: Joursoir <chat@joursoir.net>
Date: Sat, 10 Apr 2021 10:35:22 +0000
Subject: game: add dependent celestial objects

---
 src/game/CelestialObject.cpp | 31 ++++++++++++++++++++++++-------
 src/game/CelestialObject.hpp | 14 +++++++++-----
 2 files changed, 33 insertions(+), 12 deletions(-)

diff --git a/src/game/CelestialObject.cpp b/src/game/CelestialObject.cpp
index 4016391..12153ae 100644
--- a/src/game/CelestialObject.cpp
+++ b/src/game/CelestialObject.cpp
@@ -34,9 +34,10 @@ void CelestialObject::SetRadius(float object_r, float orbital_r)
 	orbital_radius = orbital_r;
 }
 
-void CelestialObject::SetTilt(float angle)
+void CelestialObject::SetTilts(float rot_axis, float rot_ecliptic)
 {
-	tilt_angle = radians(angle);
+	rotation_axis_tilt = radians(90.0f + rot_axis);
+	rotation_ecliptic_tilt = radians(rot_ecliptic);
 }
 
 void CelestialObject::SetPosition(glm::vec3 orbital)
@@ -44,21 +45,30 @@ void CelestialObject::SetPosition(glm::vec3 orbital)
 	orbital_pos = orbital;
 }
 
+void CelestialObject::AddSlave(CelestialObject *slave)
+{
+	struct linked_list<CelestialObject> *list;
+	list = new struct linked_list<CelestialObject>(slave, slaves);
+	slaves = list;
+}
+
 void CelestialObject::Draw(float time, float game_speed,
 	unsigned int model_loc)
 {
 	float
 		orb_speed = orbital_speed * game_speed,
 		rot_speed = rotation_speed * game_speed,
-		moveX = sin(radians(time) * orb_speed) * orbital_radius,
-		moveZ = cos(radians(time) * orb_speed) * orbital_radius;
+		rt_angle = radians(time) * orb_speed,
+		move_x = sin(rt_angle) * orbital_radius,
+		move_y = 0,
+		move_z = cos(rt_angle) * orbital_radius;
 
 	texture->Bind();
 
 	mat4 sphere_model(1.0f);
-	vec3 pos(orbital_pos.x - moveX, orbital_pos.y, orbital_pos.z - moveZ);
+	vec3 pos(orbital_pos.x - move_x, orbital_pos.y - move_y, orbital_pos.z - move_z);
 	sphere_model = translate(sphere_model, pos);
-	sphere_model = rotate(sphere_model, tilt_angle, vec3(1.0f, 0.0f, 0.0f));
+	sphere_model = rotate(sphere_model, rotation_axis_tilt, vec3(1.0f, 0.0f, 0.0f));
 	sphere_model = rotate(sphere_model, radians(time) * rot_speed, vec3(0.0f, 0.0f, 1.0f));
 	sphere_model = scale(sphere_model, vec3(object_radius, object_radius, object_radius));
 	glUniformMatrix4fv(model_loc, 1, GL_FALSE, value_ptr(sphere_model));
@@ -67,8 +77,15 @@ void CelestialObject::Draw(float time, float game_speed,
 	if(orbital_radius != 0.0f) {
 		mat4 circle_model(1.0f);
 		circle_model = translate(circle_model, orbital_pos);
+		// circle_model = rotate(circle_model, rotation_ecliptic_tilt, vec3(1.0f, 0.0f, 0.0f));
 		circle_model = scale(circle_model, vec3(orbital_radius, orbital_radius, orbital_radius));
 		glUniformMatrix4fv(model_loc, 1, GL_FALSE, value_ptr(circle_model));
 		circle->Draw();
 	}
-}
\ No newline at end of file
+
+	struct linked_list<CelestialObject> *ptr;
+	for(ptr = slaves; ptr; ptr = ptr->next) {
+		ptr->data->SetPosition(pos);
+		ptr->data->Draw(time, game_speed, model_loc);
+	}
+}
diff --git a/src/game/CelestialObject.hpp b/src/game/CelestialObject.hpp
index 8997697..a883fc3 100644
--- a/src/game/CelestialObject.hpp
+++ b/src/game/CelestialObject.hpp
@@ -3,6 +3,8 @@
 
 #include <glm/glm.hpp>
 
+#include "../xstdlib/xstdlib.hpp"
+
 class Texture;
 class Mesh;
 
@@ -12,6 +14,8 @@ class CelestialObject {
 	static Mesh *sphere;
 	static Mesh *circle;
 
+	struct linked_list<CelestialObject> *slaves;
+
 	/* time a given astronomical object takes to complete
 	one orbit around another object */
 	float orbital_period;
@@ -23,19 +27,19 @@ class CelestialObject {
 	around its axis of rotation relative to the background stars */
 	float rotation_period;
 	float rotation_speed;
+	float rotation_axis_tilt;
+	float rotation_ecliptic_tilt;
 
 	float object_radius;
-
-	float tilt_angle;
 public:
-	CelestialObject(Texture *t)
-		: texture(t) { }
+	CelestialObject(Texture *t) : texture(t), slaves(0) { }
 	static void InitializeMesh();
 	void SetPeriod(float a_orbital, float a_rotation);
 	void SetRadius(float object_r, float orbital_r);
-	void SetTilt(float angle);
+	void SetTilts(float rot_axis, float rot_ecliptic);
 	void SetPosition(glm::vec3 orbital);
 
+	void AddSlave(CelestialObject *slave);
 	void Draw(float time, float game_speed, unsigned int model_loc);
 
 };
-- 
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