add a focus_camera function to rederer for debugging

src/main.cpp

@@ -8,7 +8,8 @@
 #include <cmath>
 
 // Configuration defaults - edit to change default run mode
-#define DEFAULT_CONFIG_FILE "configs/test_simple.toml"
+//#define DEFAULT_CONFIG_FILE "configs/test_simple.toml"
+#define DEFAULT_CONFIG_FILE "tests/configs/solar_system.toml"
 
 struct ProgramArgs {
     const char* config_file;
@@ -64,7 +65,18 @@ void run_gui_simulation(SimulationState* sim) {
             printf("Speed multiplier: %.1fx\n", speed_multiplier);
         }
 
+#if 0
+        /****
+        * Hacks ahead...
+        */
+		int focus_index = 9;
+        if (sim->body_count >= focus_index) {
+			Vector3 offset = {0, 100, 100};
+            focus_camera(&render_state, &sim->bodies[focus_index], offset);
+        }
+#else
         update_camera(&render_state);
+#endif
 
         if (!paused) {
             int steps = (int)(physics_steps_per_frame * speed_multiplier);

src/renderer.cpp

@@ -80,6 +80,12 @@ Vector3 sim_to_render(Vec3 pos, double scale) {
     };
 }
 
+void focus_camera(RenderState* render_state, CelestialBody* body, Vector3& offset) {
+    Vector3 p = sim_to_render(body->position, render_state->distance_scale);
+    render_state->camera.position = (Vector3){ p.x, p.y + offset.y, p.z + offset.z};
+    render_state->camera.target = p;
+}
+
 // Scale a radius for rendering (with minimum visible size)
 float scale_radius(double radius, double scale) {
     float scaled = (float)(radius * scale);

src/renderer.h

@@ -19,6 +19,7 @@ void close_renderer();
 // Camera setup and control
 void setup_camera(RenderState* render_state);
 void update_camera(RenderState* render_state);
+void focus_camera(RenderState* render_state, CelestialBody* body, Vector3& offset);
 
 // Rendering functions
 void render_body(CelestialBody* body, RenderState* render_state);