It works!!!

src/core/gfx.cpp

@@ -0,0 +1,74 @@
+#include "config.hpp"
+#include "hal/draw.hpp"
+#include <array>
+#include <cmath>
+#include <cstdint>
+
+struct color_stop {
+  double value;
+  draw::color_t color;
+};
+
+draw::color_t interpolateColor(double value,
+                               const std::array<color_stop, 11> &stops) {
+  if (value <= stops.front().value)
+    return stops.front().color;
+
+  if (value >= stops.back().value)
+    return stops.back().color;
+
+  for (size_t i = 0; i < stops.size() - 1; ++i) {
+    if (value >= stops[i].value && value <= stops[i + 1].value) {
+
+      double t =
+          (value - stops[i].value) / (stops[i + 1].value - stops[i].value);
+
+      draw::color_t c0 = stops[i].color;
+      draw::color_t c1 = stops[i + 1].color;
+
+      draw::color_t result;
+      result.r = static_cast<uint8_t>(std::round(c0.r + t * (c1.r - c0.r)));
+      result.g = static_cast<uint8_t>(std::round(c0.g + t * (c1.g - c0.g)));
+      result.b = static_cast<uint8_t>(std::round(c0.b + t * (c1.b - c0.b)));
+
+      return result;
+    }
+  }
+
+  // Fallback
+  return stops.back().color;
+}
+
+#ifdef METRIC
+draw::color_t get_altitude_color(uint32_t value) {
+  static constexpr std::array<color_stop, 11> stops = {{
+#ifdef METRIC
+      {0, {220, 90, 20}},
+      {150, {245, 115, 25}},
+      {300, {250, 150, 30}},
+      {600, {245, 180, 20}},
+      {1200, {225, 200, 20}},
+      {1800, {175, 215, 30}},
+      {2400, {100, 225, 50}},
+      {3000, {40, 210, 110}},
+      {6000, {40, 175, 215}},
+      {9000, {50, 110, 240}},
+      {12000, {140, 50, 220}}
+#endif
+#ifndef METRIC
+      {0, {220, 90, 20}},      // Brown/Dark Orange
+      {500, {245, 115, 25}},   // Orange
+      {1000, {250, 150, 30}},  // Light Orange
+      {2000, {245, 180, 20}},  // Yellow-Orange
+      {4000, {225, 200, 20}},  // Yellow
+      {6000, {175, 215, 30}},  // Yellow-Green
+      {8000, {100, 225, 50}},  // Light Green
+      {10000, {40, 210, 110}}, // Teal/Cyan
+      {20000, {40, 175, 215}}, // Cyan-Blue
+      {30000, {50, 110, 240}}, // Blue
+      {40000, {140, 50, 220}}  // Purple
+#endif
+  }};
+  return interpolateColor(value, stops);
+}
+#endif

src/core/gfx.hpp

@@ -0,0 +1,4 @@
+#pragma once
+#include "hal/draw.hpp"
+#include <cstdint>
+draw::color_t get_altitude_color(uint32_t value);

src/core/units.hpp

@@ -0,0 +1,5 @@
+#pragma once
+template<typename T>
+static inline T feet_to_meters(T ft) {
+        return static_cast<T>(ft * 0.3048);
+}

src/main.cpp

@@ -2,6 +2,7 @@
 #include "core/color.h"
 #include "core/config.hpp"
 #include "core/const.hpp"
+#include "core/units.hpp"
 #include "hal/draw.hpp"
 #include "hal/hal.hpp"
 #include "hal/net.hpp"
@@ -12,6 +13,7 @@
 #include <iostream>
 #include "core/global.hpp"
 #include "core/geo.hpp"
+#include "core/gfx.hpp"
 
 int main() {
   if (hal::init() != 0) {
@@ -76,12 +78,28 @@ int main() {
       nlohmann::json aircraft = net::http_get_json(std::format("{}/aircraft.json", base_url));
       if (aircraft!= nullptr) {
         for(nlohmann::json &craft : aircraft["aircraft"]) {
+          
+          uint32_t altitude;
+          try {
+            if(craft["alt_baro"].is_string()) {
+              altitude = 0;
+            } else {
+              altitude =craft["alt_baro"].get<uint32_t>();
+              #ifdef METRIC
+              altitude = feet_to_meters(altitude);
+              #endif
+            }
+          } catch(...) {
+            std::clog << YELLOW"[WARNING]" RESET " aircraft with no alt data detected!\n";
+            altitude = 0;
+          }
+          draw::color_t color= get_altitude_color(altitude);
           try {
           const auto [x_offset,y_offset] = get_offset_from_station(craft["lat"].get<double>(), craft["lon"].get<double>());
           const uint16_t x_center = middle_x+((x_offset/1000)*pixels_per_km);
           const uint16_t y_center = middle_y+((y_offset/1000)*pixels_per_km);
-          draw::pixel(x_center, y_center, {0xff,0x68,0x00});
+          draw::pixel(x_center, y_center, color);
-          draw::rhombus(x_center, y_center, 8/*TODO: remove magic*/,{0xff,0x68,0x00}); 
+          draw::rhombus(x_center, y_center, 8/*TODO: remove magic*/,color); 
         } catch(...) {
           std::clog << YELLOW"[WARNING]" RESET " aircraft with no lat/lon data detected!\n";
         }