feat: add particle map

README.md

@@ -0,0 +1,9 @@
+# Skein
+
+Skein is a library for efficiently simulating Keplerian astrodynamics. 
+
+## Usage
+
+Kepler models orbiting bodies as particles. Particles are zero-dimensional objects which can be on elliptical orbits around other particles. The orbited particle is assumed to make up the overwhelming majority of the mass of the combined two-object system.
+
+

lib/skein/CMakeLists.txt

@@ -4,6 +4,7 @@ project(skein)
 add_library(skein STATIC
     src/orbit.cpp
     src/particle.cpp
+    src/particlemap.cpp
 )
 
 target_include_directories(skein PUBLIC

lib/skein/include/skein/particle.h

@@ -2,14 +2,19 @@
 
 #include <skein/orbit.h>
 
+#include <string>
+
 class Particle
 {
 public:
-    Particle() = default;
+    Particle(const std::string& id, double mass);
+    Particle(const Particle& other);
     ~Particle() = default;
 
-    Orbit& getOrbit();
+    const std::string& getId() const;
+    double getMass() const;
 
 private:
-    Orbit _orbit;
+    const std::string _id;
+    const double _mass;
 };

lib/skein/include/skein/particlemap.h

@@ -0,0 +1,27 @@
+#pragma once
+
+#include "skein/particle.h"
+
+#include <string>
+#include <map>
+
+class ParticleMap
+{
+    public:
+        ParticleMap() = default;
+        ~ParticleMap() = default;
+
+        // providing these as two methods keeps things unambiguous - manipulating particles
+        // is just done for setup
+        const Particle& getParticle(const std::string& id) const;
+        glm::vec3 getParticlePosition(const std::string& id, double time) const;
+        const Orbit& getOrbit(const std::string& id) const;
+
+        void setParticle(const Particle& particle);
+        void setRelationship(const std::string& parentId, const std::string& childId, const Orbit& orbit);
+
+    private:
+        std::map<std::string, Particle> _particles;
+        std::map<std::string, std::string> _relationships;
+        std::map<std::string, Orbit> _orbits;
+};

lib/skein/src/particle.cpp

@@ -1,7 +1,21 @@
 #include "skein/particle.h"
 
-Orbit& Particle::getOrbit()
+Particle::Particle(const std::string& id, double mass)
+    : _id(id), _mass(mass)
 {
-    return _orbit;
 }
 
+Particle::Particle(const Particle& other)
+    : _id(other.getId()), _mass(other.getMass())
+{
+}
+
+const std::string& Particle::getId() const
+{
+    return _id;
+}
+
+double Particle::getMass() const
+{
+    return _mass;
+}

lib/skein/src/particlemap.cpp

@@ -0,0 +1,39 @@
+#include "skein/particlemap.h"
+#include "skein/particle.h"
+
+
+const Particle& ParticleMap::getParticle(const std::string& id) const
+{
+    return _particles.at(id);
+}
+
+const Orbit& ParticleMap::getOrbit(const std::string& id) const
+{
+    return _orbits.at(id);
+}
+
+glm::vec3 ParticleMap::getParticlePosition(const std::string& id, double time) const
+{
+    // TODO: actually nest stuff so position is determined from all parents
+
+    if (_orbits.find(id) != _orbits.end())
+    {
+        const Orbit& orbit = _orbits.at(id);
+        return orbit.getPosition(time);
+    }
+
+    return {0,0,0};
+}
+
+void ParticleMap::setParticle(const Particle& particle)
+{
+    _particles.insert({particle.getId(), particle});
+}
+
+void ParticleMap::setRelationship(const std::string& parentId, const std::string& childId, const Orbit& orbit)
+{
+    // map children to parent - children can only have one parent, so we use the map to
+    // identify the parent directly using the child as the key
+    _relationships.insert({childId, parentId});
+    _orbits.insert({childId, orbit});
+}

src/gfx.cpp

@@ -110,7 +110,7 @@ GLuint compileShaderProgram(const std::string& fragShaderPath)
 
 void updateProjectionMatrix(GLuint shaderProgram)
 {
-    float left = -aspect_, right = aspect_, bottom = -1.0, top = 1.0, near = -1.0, far = 1.0;
+    float left = -aspect_, right = aspect_, bottom = -1.0, top = 1.0, near = -2.0, far = 1.0;
     glm::mat4 projection = glm::ortho(left, right, bottom, top, near, far);
     GLint projectionLocation = getShaderUniformLocation(shaderProgram, "_Projection");
     glUniformMatrix4fv(projectionLocation, 1, GL_FALSE, &projection[0][0]);

src/main.cpp

@@ -47,6 +47,7 @@
 
 #include <skein/orbit.h>
 #include <skein/particle.h>
+#include <skein/particlemap.h>
 
 // INPUT!
 //
@@ -92,19 +93,26 @@ int main()
     GLuint litProgram = compileShaderProgram("./frag_lit.glsl");
     GLuint unlitProgram = compileShaderProgram("./frag_unlit.glsl");
 
-    // set up scene
-    Icosphere planet(0.2, 3, litProgram);
+    // set parameters of moon's orbit around earth
+    Orbit orbit;
+    orbit.setSemiMajorAxis(1.0);             // in km
+    // TODO: implement zoom
+    //orbit.setSemiMajorAxis(384748);             // in km
+    orbit.setEccentricity(0.055);
+    orbit.setInclination(5.15);                 // degreees
+    orbit.setArgumentOfPeriapsis(318.15);       // in the case of the moon these last two values are
+    orbit.setLongitudeOfAscendingNode(60.0);    // pretty much constantly changing so use whatever
 
-    Particle particle;
-    Orbit& orbit = particle.getOrbit();
-    orbit.setSemiMajorAxis(.75);
-    orbit.setEccentricity(.5);
-    orbit.setInclination(3.142 / 2.0 + 1);
-    orbit.setArgumentOfPeriapsis(2.0);
-    orbit.setLongitudeOfAscendingNode(0.1);
-
-    ParticleVisualizer particleVisualizer(particle, litProgram, unlitProgram);
-    OrbitVisualizer orbitVisualizer(orbit, unlitProgram);
+    // TODO: add something in a nice eccentric orbit around the moon
+    // make the earth-moon system
+    ParticleMap map;
+    map.setParticle({"moon", 7.3e22});
+    map.setParticle({"earth", 5.9e24});
+    map.setRelationship("moon", "earth", orbit);
+    // TODO: there is a bug where re-ordering the visualizers breaks rendering
+    ParticleVisualizer moonVis(map, "moon", 0.1, litProgram, unlitProgram);
+    ParticleVisualizer earthVis(map, "earth", 0.2, litProgram, unlitProgram);
+    OrbitVisualizer orbitVis(orbit, unlitProgram);
 
     // register input
     glfwSetKeyCallback(window, keyCallback);
@@ -148,9 +156,9 @@ int main()
         glClearColor(0.2, 0.3, 0.3, 1.0);
         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
-        planet.render(time);
-        particleVisualizer.render(time);
-        orbitVisualizer.render(time);
+        earthVis.render(time);
+        moonVis.render(time);
+        orbitVis.render(time);
 
         glfwSwapBuffers(window);
     }

src/particlevisualizer.cpp

@@ -1,21 +1,24 @@
 #include "particlevisualizer.hpp"
 
-ParticleVisualizer::ParticleVisualizer(Particle& particle, GLuint sphereShaderProgram, GLuint widgetShaderProgram)
-    : _particle(particle), _sphere({0.07, 2, sphereShaderProgram}), _widget(widgetShaderProgram)
+ParticleVisualizer::ParticleVisualizer(const ParticleMap& map, const std::string& particleId, float radius,
+        GLuint sphereShaderProgram, GLuint widgetShaderProgram)
+    : _map(map), _particleId(particleId), _sphere({radius, 2, sphereShaderProgram}), _widget(widgetShaderProgram)
 {
 }
 
 void ParticleVisualizer::render(float time)
 {
-    const Orbit& orbit = _particle.getOrbit();
-
+    // TODO: get mean anomly from particle which has the mass!!
     const float meanAnomaly = time;
-    glm::vec3 pos = orbit.getPosition(meanAnomaly);
+    glm::vec3 pos = _map.getParticlePosition(_particleId, meanAnomaly);
 
-    // render widget
-    glm::mat4 widgetMatrix = orbit.getLookAlongMatrix(time);
-    _widget.setModelMatrix(widgetMatrix);
-    _widget.render(time);
+    // TODO: extract widget to its own visualizer since we know it wants an orbit but we
+    // might not have one here
+    //// render widget
+    //const Orbit& orbit = _map.getOrbit(_particleId);
+    //glm::mat4 widgetMatrix = orbit.getLookAlongMatrix(time);
+    //_widget.setModelMatrix(widgetMatrix);
+    //_widget.render(time);
 
     // render sphere
     _sphere.setPosition(pos);

src/particlevisualizer.hpp

@@ -3,12 +3,12 @@
 #include "widget.hpp"
 #include "icosphere.hpp"
 
-#include <skein/particle.h>
+#include <skein/particlemap.h>
 
 class ParticleVisualizer
 {
     public:
-        ParticleVisualizer(Particle& particle, GLuint sphereShaderProgram, GLuint widgetShaderProgram);
+        ParticleVisualizer(const ParticleMap& map, const std::string& particleId, float radius, GLuint sphereShaderProgram, GLuint widgetShaderProgram);
         ~ParticleVisualizer() = default;
 
         void render(float time);
@@ -16,7 +16,8 @@ class ParticleVisualizer
     private:
         void updateModelMatrix();
 
-        Particle& _particle;
+        const ParticleMap& _map;
+        const std::string& _particleId;
         Icosphere _sphere;
         Widget _widget;
 };