feat: port multi-satellite 2D ground tracks

src/core/theme.cpp

@@ -111,6 +111,16 @@ void ThemeInitDefaults(Theme *t)
     t->world.footprint_fill   = ParseHexColor("#FFFFFF22", WHITE);
     t->world.footprint_border = ParseHexColor("#FFFFFF88", WHITE);
 
+    // multi-satellite future ground-track palette
+    t->ground_tracks.palette[0] = ParseHexColor("#66CCFFFF", SKYBLUE);
+    t->ground_tracks.palette[1] = ParseHexColor("#66FF66FF", GREEN);
+    t->ground_tracks.palette[2] = ParseHexColor("#FFAA00FF", ORANGE);
+    t->ground_tracks.palette[3] = ParseHexColor("#FF66CCFF", MAGENTA);
+    t->ground_tracks.palette[4] = ParseHexColor("#AA66FFFF", PURPLE);
+    t->ground_tracks.palette[5] = ParseHexColor("#FF6666FF", RED);
+    t->ground_tracks.palette[6] = ParseHexColor("#66A3FFFF", BLUE);
+    t->ground_tracks.palette[7] = ParseHexColor("#2DD4BFFF", GREEN);
+
     // compact semantic UI palette (match themes/default/theme.json)
     t->ui.text    = ParseHexColor("#FFFFFFFF", WHITE);
     t->ui.text_dim = ParseHexColor("#D3D3D3FF", LIGHTGRAY);
@@ -209,6 +219,7 @@ bool ThemeLoad(const char *theme_name, Theme *t)
 
     const nlohmann::json root_meta     = root.value("meta", nlohmann::json::object());
     const nlohmann::json root_world    = root.value("world", nlohmann::json::object());
+    const nlohmann::json root_ground_tracks = root.value("ground_tracks", nlohmann::json::object());
     const nlohmann::json root_ui       = root.value("ui", nlohmann::json::object());
     const nlohmann::json root_style    = root.value("style", nlohmann::json::object());
     const nlohmann::json root_font     = root.value("font", nlohmann::json::object());
@@ -232,6 +243,22 @@ bool ThemeLoad(const char *theme_name, Theme *t)
     ParseColorField(root_world, "footprint_fill", &t->world.footprint_fill, t->world.footprint_fill);
     ParseColorField(root_world, "footprint_border", &t->world.footprint_border, t->world.footprint_border);
 
+    // multi-satellite future ground-track palette
+    auto ground_track_palette = root_ground_tracks.find("palette");
+    if (ground_track_palette != root_ground_tracks.end() && ground_track_palette->is_array())
+    {
+        for (int i = 0; i < GROUND_TRACK_PALETTE_SIZE &&
+                        i < (int)ground_track_palette->size(); i++)
+        {
+            if (ground_track_palette->at(i).is_string())
+            {
+                t->ground_tracks.palette[i] = ParseHexColor(
+                    ground_track_palette->at(i).get_ref<const std::string &>().c_str(),
+                    t->ground_tracks.palette[i]);
+            }
+        }
+    }
+
     // compact UI palette
     ParseColorField(root_ui, "text", &t->ui.text, t->ui.text);
     ParseColorField(root_ui, "text_dim", &t->ui.text_dim, t->ui.text_dim);

src/core/theme.h

@@ -27,6 +27,9 @@
 /** mix ratio applied to derive an active/pressed state from a base color */
 #define THEME_STATE_ACTIVE 0.18f
 
+/** number of colors available for multi-satellite ground tracks */
+#define GROUND_TRACK_PALETTE_SIZE 8
+
 /** compact semantic UI palette (11 colors) */
 typedef struct
 {
@@ -120,6 +123,11 @@ typedef struct
         Color footprint_border; /* coverage footprint outline */
     } world;
 
+    struct
+    {
+        Color palette[GROUND_TRACK_PALETTE_SIZE]; /* Multi track colors */
+    } ground_tracks;
+
     ThemeUIColors ui;
     ThemeStyle style;
     ThemeFont font;

src/main.cpp

@@ -168,6 +168,12 @@ static Mesh GenEarthMesh(float radius, int slices, int rings)
     return mesh;
 }
 
+/** Pick a theme-defined color for an additional 2D future ground track. */
+static Color MultiGroundTrackColor(int index)
+{
+    return g_theme.ground_tracks.palette[index % GROUND_TRACK_PALETTE_SIZE];
+}
+
 /** render orbit lines in 3d space */
 static void draw_orbit_3d(Satellite *sat, double current_epoch, bool is_highlighted, float alpha, int step)
 {
@@ -1697,6 +1703,62 @@ int main(void)
                     }
                 }
 
+                /* Future ground tracks share a fixed propagation budget in Multi mode.
+                 * The focused satellite keeps the original resolution; the remaining
+                 * budget is split across a maximum of eight active tracks in total. */
+                const bool future_orbits_enabled =
+                    ToolSettingGetBool(&cfg, LAYERS_KEY_FUTURE_ORBITS, true);
+                const int future_orbits_mode =
+                    ToolSettingGetInt(&cfg, LAYERS_KEY_FUTURE_ORBITS_MODE,
+                                      LAYERS_FUTURE_ORBITS_FOCUSED);
+                const bool future_orbits_multi =
+                    future_orbits_mode == LAYERS_FUTURE_ORBITS_MULTI;
+                const bool focused_track_valid =
+                    active_sat && active_sat->is_active && active_sat->mean_motion > 0.0 &&
+                    !(is_pov_mode && active_sat == selected_sat);
+
+                const float future_orbit_span = fmaxf(cfg.orbits_to_draw, 0.25f);
+                const int requested_future_segments =
+                    (int)fminf(4000.0f, fmaxf(50.0f, 400.0f * future_orbit_span));
+                const int future_segment_budget = 6000;
+                int extra_track_limit = future_orbits_multi
+                    ? LAYERS_FUTURE_ORBITS_MAX_TRACKS - (focused_track_valid ? 1 : 0)
+                    : 0;
+                if (extra_track_limit < 0)
+                    extra_track_limit = 0;
+
+                int extra_track_count = 0;
+                if (future_orbits_enabled && future_orbits_multi)
+                {
+                    for (int i = 0; i < sat_count && extra_track_count < extra_track_limit; i++)
+                    {
+                        const Satellite *sat = &satellites[i];
+                        if (!sat->is_active || sat->mean_motion <= 0.0 || sat == active_sat)
+                            continue;
+                        if (is_pov_mode && sat == selected_sat)
+                            continue;
+                        extra_track_count++;
+                    }
+                }
+
+                int extra_future_segments = requested_future_segments;
+                if (extra_track_count > 0)
+                {
+                    const int focused_cost = focused_track_valid ? requested_future_segments : 0;
+                    const int remaining_budget = future_segment_budget - focused_cost;
+                    extra_future_segments = remaining_budget / extra_track_count;
+                    if (extra_future_segments > requested_future_segments)
+                        extra_future_segments = requested_future_segments;
+                    if (extra_future_segments < 50)
+                        extra_future_segments = 50;
+                }
+
+                Vector3 future_sun_dir = {0};
+                if (future_orbits_enabled && cfg.highlight_sunlit)
+                    future_sun_dir = Vector3Normalize(calculate_sun_position(current_epoch));
+
+                int extra_tracks_drawn = 0;
+
                 /* render all satellites on 2d map */
                 for (int i = 0; i < sat_count; i++)
                 {
@@ -1711,20 +1773,33 @@ int main(void)
                     Color sCol = (selected_sat == &satellites[i]) ? g_theme.world.sat_selected : (hovered_sat == &satellites[i]) ? g_theme.world.sat_hover : g_theme.world.sat;
                     sCol = ApplyAlpha(sCol, sat_alpha);
 
-                    if (is_hl && !(is_pov_mode && &satellites[i] == selected_sat) && ToolSettingGetBool(&cfg, LAYERS_KEY_FUTURE_ORBITS, true))
+                    bool draw_future_track = false;
+                    if (future_orbits_enabled && satellites[i].mean_motion > 0.0 &&
+                        !(is_pov_mode && &satellites[i] == selected_sat))
+                    {
+                        if (is_hl)
+                        {
+                            draw_future_track = true;
+                        }
+                        else if (future_orbits_multi && extra_tracks_drawn < extra_track_count)
+                        {
+                            extra_tracks_drawn++;
+                            draw_future_track = true;
+                        }
+                    }
+
+                    if (draw_future_track)
                     {
-                        int segments = fmin(4000, fmax(50, (int)(400 * cfg.orbits_to_draw)));
+                        const int segments = is_hl ? requested_future_segments : extra_future_segments;
                         Vector2 track_pts[4001];
                         bool is_sunlit_arr[4001];
 
-                        double period_days = (2.0 * PI / satellites[i].mean_motion) / 86400.0;
-                        double time_step = (period_days * cfg.orbits_to_draw) / segments;
+                        const Color track_color = ApplyAlpha(
+                            is_hl ? g_theme.world.orbit_active : MultiGroundTrackColor(i),
+                            sat_alpha);
 
-                        Vector3 base_sun_dir = {0};
-                        if (cfg.highlight_sunlit)
-                        {
-                            base_sun_dir = Vector3Normalize(calculate_sun_position(current_epoch));
-                        }
+                        double period_days = (2.0 * PI / satellites[i].mean_motion) / 86400.0;
+                        double time_step = (period_days * future_orbit_span) / segments;
 
                         for (int j = 0; j <= segments; j++)
                         {
@@ -1735,31 +1810,25 @@ int main(void)
 
                             if (cfg.highlight_sunlit)
                             {
-                                is_sunlit_arr[j] = !is_sat_eclipsed(raw_pos, base_sun_dir);
+                                is_sunlit_arr[j] = !is_sat_eclipsed(raw_pos, future_sun_dir);
                             }
                         }
 
                         for (int offset_i = -1; offset_i <= 1; offset_i++)
                         {
                             float x_off = offset_i * map_w;
-                            bool is_selected = (selected_sat == &satellites[i]);
                             for (int j = 1; j <= segments; j++)
                             {
                                 if (fabs(track_pts[j].x - track_pts[j - 1].x) < map_w * 0.6f)
                                 {
-                                    Color drawCol = ApplyAlpha(is_hl ? g_theme.world.orbit_active : g_theme.world.orbit, sat_alpha);
-                                    if (cfg.highlight_sunlit)
-                                    {
-                                        if (is_sunlit_arr[j])
-                                            drawCol = ApplyAlpha(g_theme.world.sat_hover, sat_alpha);
-                                        else
-                                            drawCol = ApplyAlpha(is_hl ? g_theme.world.orbit_active : g_theme.world.orbit, sat_alpha);
-                                    }
+                                    Color drawCol = track_color;
+                                    if (cfg.highlight_sunlit && is_sunlit_arr[j])
+                                        drawCol = ApplyAlpha(g_theme.world.sat_hover, sat_alpha);
                                     DrawLineEx((Vector2){track_pts[j - 1].x + x_off, track_pts[j - 1].y}, (Vector2){track_pts[j].x + x_off, track_pts[j].y}, 2.0f / Camera2DParams.zoom, drawCol);
                                 }
                             }
 
-                            if (cfg.show_apsides)
+                            if (cfg.show_apsides && is_hl)
                             {
                                 Vector2 peri2d, apo2d;
                                 get_apsis_2d(&satellites[i], current_epoch, false, gmst_deg, cfg.earth_rotation_offset, map_w, map_h, &peri2d);

src/ui/tools/tool_layers.cpp

@@ -218,10 +218,10 @@ void DrawPanelLayers(UIContext *ctx, AppConfig *cfg)
 
     if (is_2d)
     {
-        /* Future Orbits: master toggle + slider, styled to match the other layer rows (icon cell + label) */
+        /* Future Orbits: master toggle + focused/multi scope + orbit span. */
         bool future_orbits_enabled = ToolSettingGetBool(cfg, LAYERS_KEY_FUTURE_ORBITS, true);
         bool future_orbits_prev = future_orbits_enabled;
-        float future_row_avail = ImGui::GetContentRegionAvail().x; /* full row width, for right-aligning the slider */
+        float future_row_avail = ImGui::GetContentRegionAvail().x;
 
         ImGui::PushStyleColor(ImGuiCol_Text, ThemeColor(future_orbits_enabled ? g_theme.ui.accent : g_theme.ui.text_dim));
         ImU32 col = ImGui::GetColorU32(ImGuiCol_Text);
@@ -234,20 +234,43 @@ void DrawPanelLayers(UIContext *ctx, AppConfig *cfg)
         ImGui::SameLine();
         ImGui::Checkbox("Future Orbits", &future_orbits_enabled);
         if (ImGui::IsItemHovered())
-            ImGui::SetTooltip("Show the predicted future orbit track on the 2D map");
+            ImGui::SetTooltip("Show predicted future ground tracks on the 2D map");
         if (future_orbits_enabled != future_orbits_prev)
             ToolSettingSetBool(cfg, LAYERS_KEY_FUTURE_ORBITS, future_orbits_enabled);
 
-        /* right-align the slider on the row, like the Labels Sel/All dropdown above */
-        const float slider_w = 140.0f;
-        ImGui::SameLine(future_row_avail - slider_w);
-        ImGui::SetNextItemWidth(slider_w);
         ImGui::BeginDisabled(!future_orbits_enabled);
-        float future_orbits = cfg->orbits_to_draw;
-        if (ImGui::SliderFloat("##future_orbits", &future_orbits, 0.25f, 10.0f, "%.2f"))
-            cfg->orbits_to_draw = future_orbits;
+
+        ImGui::SameLine(future_row_avail - combo_w);
+        ImGui::SetNextItemWidth(combo_w);
+        int future_mode = ToolSettingGetInt(
+            cfg, LAYERS_KEY_FUTURE_ORBITS_MODE, LAYERS_FUTURE_ORBITS_FOCUSED);
+        const char *future_modes[] = { "Sel", "Multi" };
+        if (ImGui::Combo("##future_orbits_mode", &future_mode, future_modes, 2))
+            ToolSettingSetInt(cfg, LAYERS_KEY_FUTURE_ORBITS_MODE, future_mode);
         if (ImGui::IsItemHovered())
-            ImGui::SetTooltip("Number of predicted orbits shown on the 2D map");
+            ImGui::SetTooltip(
+                "Sel: hovered satellite, otherwise selected satellite; "
+                "Multi: up to %d active satellite tracks total",
+                LAYERS_FUTURE_ORBITS_MAX_TRACKS);
+
+        ImGui::Indent(icon_w);
+        int orbit_quarters = (int)roundf(cfg->orbits_to_draw * 4.0f);
+        if (orbit_quarters < 1) orbit_quarters = 1;
+        if (orbit_quarters > 40) orbit_quarters = 40;
+
+        const float orbit_value_w =
+            ImGui::CalcTextSize("10.00").x + ImGui::GetStyle().ItemSpacing.x;
+        ImGui::SetNextItemWidth(future_row_avail - icon_w - orbit_value_w);
+        ImGui::SliderInt("##future_orbits", &orbit_quarters, 1, 40, "");
+        const bool orbit_slider_hovered = ImGui::IsItemHovered();
+        cfg->orbits_to_draw = orbit_quarters * 0.25f;
+
+        ImGui::SameLine();
+        ImGui::Text("%.2f", cfg->orbits_to_draw);
+        if (orbit_slider_hovered || ImGui::IsItemHovered())
+            ImGui::SetTooltip("Number of predicted orbits shown for each future ground track (0.25-orbit steps)");
+        ImGui::Unindent(icon_w);
+
         ImGui::EndDisabled();
     }
 

src/ui/tools/tools_common.h

@@ -21,6 +21,12 @@ extern bool log_show_timestamps;    /* show timestamps in log entries (default o
 /* master switch for the 2D "Future Orbits" track (bool, default true) */
 #define LAYERS_KEY_FUTURE_ORBITS "layers.future_orbits"
 
+/* Future Orbits scope: focused track only, or a bounded multi-track set. */
+#define LAYERS_KEY_FUTURE_ORBITS_MODE       "layers.future_orbits_mode"
+#define LAYERS_FUTURE_ORBITS_FOCUSED        0
+#define LAYERS_FUTURE_ORBITS_MULTI          1
+#define LAYERS_FUTURE_ORBITS_MAX_TRACKS     8
+
 /* universal master switch for the Earth surface texture (bool, default true).
  * When off, the Earth renders as a plain black body in both the 2D map and the
  * 3D globe (see main.cpp). */

themes/amber/theme.json

@@ -17,6 +17,13 @@
         "footprint_fill": "#E8C98A22",
         "footprint_border": "#E8C98A88"
     },
+    "ground_tracks": {
+        "palette": [
+            "#66CCFFFF", "#34D399FF", "#F97316FF",
+            "#FB7185FF", "#C084FCFF", "#FACC15FF",
+            "#60A5FAFF", "#2DD4BFFF"
+        ]
+    },
     "ui": {
         "text": "#F5E9D0FF",
         "text_dim": "#B8A88CFF",

themes/daylight/theme.json

@@ -17,6 +17,13 @@
         "footprint_fill": "#1E3A5F22",
         "footprint_border": "#1E3A5F88"
     },
+    "ground_tracks": {
+        "palette": [
+            "#0369A1FF", "#059669FF", "#C2410CFF",
+            "#BE185DFF", "#7E22CEFF", "#B91C1CFF",
+            "#1D4ED8FF", "#0F766EFF"
+        ]
+    },
     "ui": {
         "text": "#1F2937FF",
         "text_dim": "#6B7280FF",

themes/default/theme.json

@@ -17,6 +17,13 @@
         "footprint_fill": "#FFFFFF22",
         "footprint_border": "#FFFFFF88"
     },
+    "ground_tracks": {
+        "palette": [
+            "#66CCFFFF", "#66FF66FF", "#FFAA00FF",
+            "#FF66CCFF", "#AA66FFFF", "#FF6666FF",
+            "#66A3FFFF", "#2DD4BFFF"
+        ]
+    },
     "ui": {
         "text": "#FFFFFFFF",
         "text_dim": "#D3D3D3FF",

themes/girlypop/theme.json

@@ -17,6 +17,13 @@
         "footprint_fill": "#E5E7EB22",
         "footprint_border": "#E5E7EB88"
     },
+    "ground_tracks": {
+        "palette": [
+            "#38BDF8FF", "#34D399FF", "#FB7185FF",
+            "#F472B6FF", "#C084FCFF", "#F97316FF",
+            "#818CF8FF", "#14B8A6FF"
+        ]
+    },
     "ui": {
         "text": "#E5E7EBFF",
         "text_dim": "#9CA3AFFF",

themes/midnight/theme.json

@@ -17,6 +17,13 @@
         "footprint_fill": "#8FA8D922",
         "footprint_border": "#8FA8D988"
     },
+    "ground_tracks": {
+        "palette": [
+            "#38BDF8FF", "#34D399FF", "#FB923CFF",
+            "#F472B6FF", "#A78BFAFF", "#F87171FF",
+            "#60A5FAFF", "#2DD4BFFF"
+        ]
+    },
     "ui": {
         "text": "#E2E8F0FF",
         "text_dim": "#94A3B8FF",

themes/paper/theme.json

@@ -17,6 +17,13 @@
         "footprint_fill": "#5B463622",
         "footprint_border": "#5B463688"
     },
+    "ground_tracks": {
+        "palette": [
+            "#0369A1FF", "#15803DFF", "#C2410CFF",
+            "#BE185DFF", "#7E22CEFF", "#B91C1CFF",
+            "#0F766EFF", "#A16207FF"
+        ]
+    },
     "ui": {
         "text": "#3B2F2FFF",
         "text_dim": "#7A6A5AFF",