sms: isolated code for updating forces

sms/sms/include/display.h

@@ -37,6 +37,9 @@ class Display : public QGLWidget {
         void set_draw_grid(bool d) {this->m_draw_grid = d;}
         void set_draw_axes(bool d) {this->m_draw_axes = d;}
 
+        const Mass * selected() const {return this->m_selected;}
+        Vector selected_force() const {return this->m_selected_force;}
+
     public slots:
         void update_systems();
 
@@ -59,6 +62,7 @@ class Display : public QGLWidget {
 
         std::vector<Simulation *> m_simulations;
         Mass * m_selected;
+        Vector m_selected_force;
         Camera m_camera;
         GLuint m_texture;
         GLUquadric * m_quadric;

sms/sms/src/display.cpp

@@ -88,7 +88,7 @@ void Display::select(Vector click, bool rate_limit) {
     glMatrixMode(GL_MODELVIEW);
     glLoadIdentity();
     Rendering::set_camera(this->m_camera);
-    Mass * selected = nullptr;
+    this->m_selected = nullptr;
     for(auto simulation : this->m_simulations)
         for(auto system : *simulation->systems()) {
             glRenderMode(GL_SELECT);
@@ -97,13 +97,12 @@ void Display::select(Vector click, bool rate_limit) {
             Rendering::draw_masses(
                 system, GL_SELECT, this->m_quadric, this->m_selected);
             if(glRenderMode(GL_RENDER) != 0) {
-                selected = &(*system->masses())[select_buffer[3]];
+                this->m_selected = &(*system->masses())[select_buffer[3]];
                 break;
             }
         }
     glMatrixMode(GL_PROJECTION);
     glPopMatrix();
-    this->m_selected = selected;
 }
 
 /*slot*/
@@ -185,7 +184,7 @@ void Display::mousePressEvent(QMouseEvent * event) {
 
 void Display::mouseReleaseEvent(QMouseEvent * event) {
     if(event->button() == Qt::LeftButton && this->m_selected)
-        this->m_selected->set_force(Vector());
+        this->m_selected_force = Vector();
 }
 
 void Display::mouseMoveEvent(QMouseEvent * event) {
@@ -206,7 +205,7 @@ void Display::mouseMoveEvent(QMouseEvent * event) {
         else if(this->m_selected) {
             auto move = (this->m_click_position - position)
                 / this->m_camera.distance();
-            this->m_selected->set_force(Vector(-move.x(), move.y()));
+            this->m_selected_force = Vector(-move.x(), move.y());
         }
     }
     this->m_last_position = position;

sms/sms/src/main.cpp

@@ -18,7 +18,8 @@ void init_sm_system3(SpringMassSystem * system, unsigned int side);
 GLuint load_texture(const std::string & filename);
 void move_system(SpringMassSystem * system, Vector v);
 
-void update_simulations(std::vector<Simulation> * simulations);
+void update_simulations(
+    std::vector<Simulation> * simulations, Display * display);
 
 int main(int argc, char ** argv) {
     const double UPDATE_RATE = 1.0f / 3000.0f;
@@ -38,7 +39,9 @@ int main(int argc, char ** argv) {
     QTimer timer;
     QObject::connect(
         &timer, &QTimer::timeout,
-        [&simulations](){update_simulations(&simulations);});
+        [&simulations, &display]() {
+            update_simulations(&simulations, &display);
+        });
     QObject::connect(
         &timer, &QTimer::timeout,
         &display, &Display::updateGL);
@@ -46,9 +49,19 @@ int main(int argc, char ** argv) {
     return app.exec();
 }
 
-void update_simulations(std::vector<Simulation> * simulations) {
-    for(auto & simulation : *simulations)
+void update_simulations(
+        std::vector<Simulation> * simulations, Display * display) {
+    const auto F = Vector();
+    for(auto & simulation : *simulations) {
+        for(auto system : *simulation.systems())
+            for(auto & mass : *system->masses()) {
+                auto f = F;
+                if(&mass == display->selected())
+                    f = f + display->selected_force();
+                mass.set_force(f);
+            }
         simulation.update();
+    }
 }
 
 void init_simulations(