diff --git a/.idea/shelf/Uncommitted_changes_before_Update_at_3_24_25,_12_40 PM_[Changes]/shelved.patch b/.idea/shelf/Uncommitted_changes_before_Update_at_3_24_25,_12_40 PM_[Changes]/shelved.patch
new file mode 100644
index 0000000..811bb2a
--- /dev/null
+++ b/.idea/shelf/Uncommitted_changes_before_Update_at_3_24_25,_12_40 PM_[Changes]/shelved.patch
@@ -0,0 +1,30 @@
+Index: crates/client/dist/index.html
+IDEA additional info:
+Subsystem: com.intellij.openapi.diff.impl.patch.BaseRevisionTextPatchEP
+<+><!DOCTYPE html>\n<html>\n<meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\" />\n\n<!-- Disable zooming: -->\n<meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0, user-scalable=no\">\n\n<head>\n    <!-- change this to your project name -->\n    <title>wxbox</title>\n    <style>\n        html {\n            /* Remove touch delay: */\n            touch-action: manipulation;\n        }\n\n        body {\n            /* Light mode background color for what is not covered by the egui canvas,\n            or where the egui canvas is translucent. */\n            background: #909090;\n        }\n\n        @media (prefers-color-scheme: dark) {\n            body {\n                /* Dark mode background color for what is not covered by the egui canvas,\n                or where the egui canvas is translucent. */\n                background: #404040;\n            }\n        }\n\n        /* Allow canvas to fill entire web page: */\n        html,\n        body {\n            overflow: hidden;\n            margin: 0 !important;\n            padding: 0 !important;\n            height: 100%;\n            width: 100%;\n        }\n\n        /* Make canvas fill entire document: */\n        canvas {\n            margin-right: auto;\n            margin-left: auto;\n            display: block;\n            position: absolute;\n            top: 0;\n            left: 0;\n            width: 100%;\n            height: 100%;\n        }\n\n        .centered {\n            margin-right: auto;\n            margin-left: auto;\n            display: block;\n            position: absolute;\n            top: 50%;\n            left: 50%;\n            transform: translate(-50%, -50%);\n            color: #f0f0f0;\n            font-size: 24px;\n            font-family: Ubuntu-Light, Helvetica, sans-serif;\n            text-align: center;\n        }\n\n        /* ---------------------------------------------- */\n        /* Loading animation from https://loading.io/css/ */\n        .lds-dual-ring {\n            display: inline-block;\n            width: 24px;\n            height: 24px;\n        }\n\n        .lds-dual-ring:after {\n            content: \" \";\n            display: block;\n            width: 24px;\n            height: 24px;\n            margin: 0px;\n            border-radius: 50%;\n            border: 3px solid #fff;\n            border-color: #fff transparent #fff transparent;\n            animation: lds-dual-ring 1.2s linear infinite;\n        }\n\n        @keyframes lds-dual-ring {\n            0% {\n                transform: rotate(0deg);\n            }\n\n            100% {\n                transform: rotate(360deg);\n            }\n        }\n    </style>\n<link rel=\"modulepreload\" href=\"/wxbox-client-505f3eac107f11ba.js\" crossorigin=\"anonymous\" integrity=\"sha384-GoFHK0g3J2PErhG84WyBgkvIzC7ysW04mj2TlSyC1OOS8y57jaSA/DvzQIC0cO8Y\"><link rel=\"preload\" href=\"/wxbox-client-505f3eac107f11ba_bg.wasm\" crossorigin=\"anonymous\" integrity=\"sha384-MOHtFF4+PhvJcmiEZcythcXE0pd0PLvpxBH/sCuHCZQL++kNK7BuI9hkBu/TWsPN\" as=\"fetch\" type=\"application/wasm\"></head>\n\n<body>\n<!-- The WASM code will resize the canvas dynamically -->\n<!-- the id is hardcoded in main.rs . so, make sure both match. -->\n<canvas id=\"the_canvas_id\"></canvas>\n\n<!-- the loading spinner will be removed in main.rs -->\n<div class=\"centered\" id=\"loading_text\">\n    <p style=\"font-size:16px\">\n        Loading…\n    </p>\n    <div class=\"lds-dual-ring\"></div>\n</div>\n\n\n<script type=\"module\">\nimport init, * as bindings from '/wxbox-client-505f3eac107f11ba.js';\nconst wasm = await init({ module_or_path: '/wxbox-client-505f3eac107f11ba_bg.wasm' });\n\n\nwindow.wasmBindings = bindings;\n\n\ndispatchEvent(new CustomEvent(\"TrunkApplicationStarted\", {detail: {wasm}}));\n\n</script><script>\"use strict\";\n\n(function () {\n\n    const address = '{{__TRUNK_ADDRESS__}}';\n    const base = '{{__TRUNK_WS_BASE__}}';\n    let protocol = '';\n    protocol =\n        protocol\n            ? protocol\n            : window.location.protocol === 'https:'\n                ? 'wss'\n                : 'ws';\n    const url = protocol + '://' + address + base + '.well-known/trunk/ws';\n\n    class Overlay {\n        constructor() {\n            // create an overlay\n            this._overlay = document.createElement(\"div\");\n            const style = this._overlay.style;\n            style.height = \"100vh\";\n            style.width = \"100vw\";\n            style.position = \"fixed\";\n            style.top = \"0\";\n            style.left = \"0\";\n            style.backgroundColor = \"rgba(222, 222, 222, 0.5)\";\n            style.fontFamily = \"sans-serif\";\n            // not sure that's the right approach\n            style.zIndex = \"1000000\";\n            style.backdropFilter = \"blur(1rem)\";\n\n            const container = document.createElement(\"div\");\n            // center it\n            container.style.position = \"absolute\";\n            container.style.top = \"30%\";\n            container.style.left = \"15%\";\n            container.style.maxWidth = \"85%\";\n\n            this._title = document.createElement(\"div\");\n            this._title.innerText = \"Build failure\";\n            this._title.style.paddingBottom = \"2rem\";\n            this._title.style.fontSize = \"2.5rem\";\n\n            this._message = document.createElement(\"div\");\n            this._message.style.whiteSpace = \"pre-wrap\";\n\n            const icon= document.createElement(\"div\");\n            icon.innerHTML = '<svg xmlns=\"http://www.w3.org/2000/svg\" width=\"64\" height=\"64\" fill=\"#dc3545\" viewBox=\"0 0 16 16\"><path d=\"M8.982 1.566a1.13 1.13 0 0 0-1.96 0L.165 13.233c-.457.778.091 1.767.98 1.767h13.713c.889 0 1.438-.99.98-1.767L8.982 1.566zM8 5c.535 0 .954.462.9.995l-.35 3.507a.552.552 0 0 1-1.1 0L7.1 5.995A.905.905 0 0 1 8 5zm.002 6a1 1 0 1 1 0 2 1 1 0 0 1 0-2z\"/></svg>';\n            this._title.prepend(icon);\n\n            container.append(this._title, this._message);\n            this._overlay.append(container);\n\n            this._inject();\n            window.setInterval(() => {\n                this._inject();\n            }, 250);\n        }\n\n        set reason(reason) {\n            this._message.textContent = reason;\n        }\n\n        _inject() {\n            if (!this._overlay.isConnected) {\n                // prepend it\n                document.body?.prepend(this._overlay);\n            }\n        }\n\n    }\n\n    class Client {\n        constructor(url) {\n            this.url = url;\n            this.poll_interval = 5000;\n            this._overlay = null;\n        }\n\n        start() {\n            const ws = new WebSocket(this.url);\n            ws.onmessage = (ev) => {\n                const msg = JSON.parse(ev.data);\n                switch (msg.type) {\n                    case \"reload\":\n                        this.reload();\n                        break;\n                    case \"buildFailure\":\n                        this.buildFailure(msg.data)\n                        break;\n                }\n            };\n            ws.onclose = () => this.onclose();\n        }\n\n        onclose() {\n            window.setTimeout(\n                () => {\n                    // when we successfully reconnect, we'll force a\n                    // reload (since we presumably lost connection to\n                    // trunk due to it being killed, so it will have\n                    // rebuilt on restart)\n                    const ws = new WebSocket(this.url);\n                    ws.onopen = () => window.location.reload();\n                    ws.onclose = () => this.onclose();\n                },\n                this.poll_interval);\n        }\n\n        reload() {\n            window.location.reload();\n        }\n\n        buildFailure({reason}) {\n            // also log the console\n            console.error(\"Build failed:\", reason);\n\n            console.debug(\"Overlay\", this._overlay);\n\n            if (!this._overlay) {\n                this._overlay = new Overlay();\n            }\n            this._overlay.reason = reason;\n        }\n    }\n\n    new Client(url).start();\n\n})()\n</script></body>\n\n</html>
+Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
+<+>UTF-8
+===================================================================
+diff --git a/crates/client/dist/index.html b/crates/client/dist/index.html
+--- a/crates/client/dist/index.html	(revision 05d33f277d6f7215045655ef624d96d1565e3662)
++++ b/crates/client/dist/index.html	(date 1742834344143)
+@@ -94,7 +94,7 @@
+             }
+         }
+     </style>
+-<link rel="modulepreload" href="/wxbox-client-505f3eac107f11ba.js" crossorigin="anonymous" integrity="sha384-GoFHK0g3J2PErhG84WyBgkvIzC7ysW04mj2TlSyC1OOS8y57jaSA/DvzQIC0cO8Y"><link rel="preload" href="/wxbox-client-505f3eac107f11ba_bg.wasm" crossorigin="anonymous" integrity="sha384-MOHtFF4+PhvJcmiEZcythcXE0pd0PLvpxBH/sCuHCZQL++kNK7BuI9hkBu/TWsPN" as="fetch" type="application/wasm"></head>
++<link rel="modulepreload" href="/wxbox-client-e197ba9e29670c90.js" crossorigin="anonymous" integrity="sha384-GoFHK0g3J2PErhG84WyBgkvIzC7ysW04mj2TlSyC1OOS8y57jaSA/DvzQIC0cO8Y"><link rel="preload" href="/wxbox-client-e197ba9e29670c90_bg.wasm" crossorigin="anonymous" integrity="sha384-MOHtFF4+PhvJcmiEZcythcXE0pd0PLvpxBH/sCuHCZQL++kNK7BuI9hkBu/TWsPN" as="fetch" type="application/wasm"></head>
+ 
+ <body>
+ <!-- The WASM code will resize the canvas dynamically -->
+@@ -111,8 +111,8 @@
+ 
+ 
+ <script type="module">
+-import init, * as bindings from '/wxbox-client-505f3eac107f11ba.js';
+-const wasm = await init({ module_or_path: '/wxbox-client-505f3eac107f11ba_bg.wasm' });
++import init, * as bindings from '/wxbox-client-e197ba9e29670c90.js';
++const wasm = await init({ module_or_path: '/wxbox-client-e197ba9e29670c90_bg.wasm' });
+ 
+ 
+ window.wasmBindings = bindings;
diff --git a/.idea/shelf/Uncommitted_changes_before_Update_at_3_24_25__12_40PM__Changes_.xml b/.idea/shelf/Uncommitted_changes_before_Update_at_3_24_25__12_40PM__Changes_.xml
new file mode 100644
index 0000000..888d6bd
--- /dev/null
+++ b/.idea/shelf/Uncommitted_changes_before_Update_at_3_24_25__12_40PM__Changes_.xml
@@ -0,0 +1,7 @@
+<changelist name="Uncommitted_changes_before_Update_at_3_24_25,_12_40 PM_[Changes]" date="1742834400705" recycled="false" toDelete="true">
+  <option name="PATH" value="$PROJECT_DIR$/.idea/shelf/Uncommitted_changes_before_Update_at_3_24_25,_12_40 PM_[Changes]/shelved.patch" />
+  <option name="DESCRIPTION" value="Uncommitted changes before Update at 3/24/25, 12:40 PM [Changes]" />
+  <binary>
+    <option name="BEFORE_PATH" value="crates/client/dist/wxbox-client-505f3eac107f11ba_bg.wasm" />
+  </binary>
+</changelist>
\ No newline at end of file
diff --git a/.idea/workspace.xml b/.idea/workspace.xml
index fc9d0dc..ebc73ff 100644
--- a/.idea/workspace.xml
+++ b/.idea/workspace.xml
@@ -8,13 +8,8 @@
   </component>
   <component name="ChangeListManager">
     <list default="true" id="2d855648-9644-469a-afa2-59beb52bb1d6" name="Changes" comment="feat: client work">
-      <change afterPath="$PROJECT_DIR$/client/src/lib/map/fragment.glsl" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/client/src/lib/map/vertex.glsl" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/.idea/.gitignore" beforeDir="false" />
-      <change beforePath="$PROJECT_DIR$/.idea/vcs.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/vcs.xml" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/.idea/wxbox.iml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/wxbox.iml" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/client/src/lib/Map.svelte" beforeDir="false" afterPath="$PROJECT_DIR$/client/src/lib/Map.svelte" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/crates/tiler/config.toml" beforeDir="false" afterPath="$PROJECT_DIR$/crates/tiler/config.toml" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/.idea/workspace.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/workspace.xml" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/client/src/lib/map/fragment.glsl" beforeDir="false" afterPath="$PROJECT_DIR$/client/src/lib/map/fragment.glsl" afterDir="false" />
     </list>
     <option name="SHOW_DIALOG" value="false" />
     <option name="HIGHLIGHT_CONFLICTS" value="true" />
@@ -39,22 +34,23 @@
     <option name="hideEmptyMiddlePackages" value="true" />
     <option name="showLibraryContents" value="true" />
   </component>
-  <component name="PropertiesComponent"><![CDATA[{
-  "keyToString": {
-    "RunOnceActivity.ShowReadmeOnStart": "true",
-    "RunOnceActivity.rust.reset.selective.auto.import": "true",
-    "git-widget-placeholder": "core/client-rewrite-again",
-    "node.js.detected.package.eslint": "true",
-    "node.js.selected.package.eslint": "(autodetect)",
-    "node.js.selected.package.tslint": "(autodetect)",
-    "nodejs_package_manager_path": "npm",
-    "org.rust.cargo.project.model.PROJECT_DISCOVERY": "true",
-    "org.rust.first.attach.projects": "true",
-    "settings.editor.selected.configurable": "preferences.pluginManager",
-    "ts.external.directory.path": "/home/core/prj/personal/wxbox/client/node_modules/typescript/lib",
-    "vue.rearranger.settings.migration": "true"
+  <component name="PropertiesComponent">{
+  &quot;keyToString&quot;: {
+    &quot;RunOnceActivity.ShowReadmeOnStart&quot;: &quot;true&quot;,
+    &quot;RunOnceActivity.git.unshallow&quot;: &quot;true&quot;,
+    &quot;RunOnceActivity.rust.reset.selective.auto.import&quot;: &quot;true&quot;,
+    &quot;git-widget-placeholder&quot;: &quot;core/client-rewrite-again&quot;,
+    &quot;node.js.detected.package.eslint&quot;: &quot;true&quot;,
+    &quot;node.js.selected.package.eslint&quot;: &quot;(autodetect)&quot;,
+    &quot;node.js.selected.package.tslint&quot;: &quot;(autodetect)&quot;,
+    &quot;nodejs_package_manager_path&quot;: &quot;npm&quot;,
+    &quot;org.rust.cargo.project.model.PROJECT_DISCOVERY&quot;: &quot;true&quot;,
+    &quot;org.rust.first.attach.projects&quot;: &quot;true&quot;,
+    &quot;settings.editor.selected.configurable&quot;: &quot;preferences.pluginManager&quot;,
+    &quot;ts.external.directory.path&quot;: &quot;/home/core/prj/personal/wxbox/client/node_modules/typescript/lib&quot;,
+    &quot;vue.rearranger.settings.migration&quot;: &quot;true&quot;
   }
-}]]></component>
+}</component>
   <component name="RunManager">
     <configuration name="Run wxbox-ar2" type="CargoCommandRunConfiguration" factoryName="Cargo Command">
       <option name="command" value="run --package wxbox-ar2 --bin wxbox-ar2" />
@@ -130,6 +126,7 @@
       <workItem from="1748031993681" duration="8000" />
       <workItem from="1748032062973" duration="74000" />
       <workItem from="1748032143420" duration="1307000" />
+      <workItem from="1748132890039" duration="1214000" />
     </task>
     <servers />
   </component>
diff --git a/client/src/lib/map/fragment.glsl b/client/src/lib/map/fragment.glsl
index 87e1f46..970e243 100644
--- a/client/src/lib/map/fragment.glsl
+++ b/client/src/lib/map/fragment.glsl
@@ -2,7 +2,11 @@
 
 precision highp float;
 
-#define PI 3.141592653589793238462643
+const float PI = 3.141592653589793238462643;
+const float PI_OVER_TWO = PI / 2.0;
+const float TWO_PI = PI + PI;
+const float NEGATIVE_PI_OVER_TWO = -PI_OVER_TWO;
+const float NEGATIVE_TWO_PI = -TWO_PI;
 
 out highp vec4 fragColor;
 uniform mat4 u_matrix;
@@ -15,57 +19,213 @@ void xyToLngLat(in float x, in float y, out float lat, out float lng) {
 
 in vec4 raw_pos;
 
-#define a 6378137.0
-#define f 1.0 / 298.257223563
-#define b 6356752.314245
+struct Ellipsoid {
+    float semiMajorAxisMeters;
+    float semiMinorAxisMeters;
+    float flattening;
+    float inverseFlattening;
+};
+Ellipsoid fromAAndInverseF(float semiMajorAxisMeters, float inverseFlattening) {
+    float f = 1.0 / inverseFlattening;
+    float b = (1.0 - f) * semiMajorAxisMeters;
 
-bool vincenty(in float phi1, in float phi2, in float l1, in float l2, out float a1, out float a2, out float s) {
-    float u1 = atan((1.0 - f) * tan(phi1));
-    float u2 = atan((1.0 - f) * tan(phi2));
-    float L = l2 - l1;
+    return Ellipsoid(semiMajorAxisMeters, b, f, inverseFlattening);
+}
 
-    float lambda = L;
+struct Angle {
+    float radians;
+};
+float angleAsDegrees(Angle angle) {
+    return degrees(angle.radians);
+}
+Angle radianAngle(float radians) {
+    return Angle(radians);
+}
+Angle degreeAngle(float degrees) {
+    return Angle(radians(degrees));
+}
 
-    float sinSigma;
-    float cosSigma;
-    float sigma;
-    float sinAlpha;
-    float cosSquaredAlpha;
-    float cos2OmegaM;
-    float C;
+struct GlobalCoordinates {
+    Angle latitude;
+    Angle longitude;
+};
+void canonicalizeGlobalCoordinates(inout GlobalCoordinates coords) {
+    float latitudeRadians = coords.latitude.radians;
+    float longitudeRadians = coords.longitude.radians;
 
-    // sometimes fails to converge. set maximum iteration count
-    int iterCount = 0;
+    latitudeRadians = mod((latitudeRadians + PI), TWO_PI);
+    if (latitudeRadians < 0.0) {
+        latitudeRadians += TWO_PI;
+    }
+    latitudeRadians -= PI;
 
-    while (lambda > pow(10.0, -12.0)) {
-        iterCount++;
-        if (iterCount > 10) {
-            return false;
-        }
-        sinSigma = sqrt(pow(cos(u2)*sin(lambda), 2.0) + pow(cos(u1)*sin(u2)-sin(u1)*cos(u2)*cos(lambda),2.0));
-        cosSigma = sin(u1)*sin(u2)+cos(u1)*cos(u2)*cos(lambda);
-        sigma = atan(sinSigma,cosSigma);
-
-        sinAlpha = (cos(u1)*cos(u2)*sin(lambda))/(sinSigma);
-        cosSquaredAlpha = 1.0 - pow(sinAlpha, 2.0);
-        cos2OmegaM = cosSigma - (2.0*sin(u1)*sin(u2))/(cosSquaredAlpha);
-        C = f/16.0 * cosSquaredAlpha * (4.0 + f * (4.0 - 3.0 * cosSquaredAlpha));
-        lambda = L + (1.0 - C) * f * sinAlpha * (sigma + C * sinSigma * (cos2OmegaM + C*cosSigma * (-1.0 + 2.0 * pow(cos2OmegaM, 2.0))));
+    if (latitudeRadians > PI_OVER_TWO) {
+        latitudeRadians = PI - latitudeRadians;
+        longitudeRadians += PI;
+    } else if (latitudeRadians < NEGATIVE_PI_OVER_TWO) {
+        latitudeRadians = -PI - latitudeRadians;
+        longitudeRadians += PI;
     }
 
-    float uSquared = cosSquaredAlpha * ((pow(a, 2.0) - pow(b, 2.0))/pow(b, 2.0));
-    float A = 1.0 + uSquared/16384.0 * (4096.0 + uSquared * (-768.0 + uSquared * (320.0 - 175.0*uSquared)));
-    float B = uSquared / 1024.0 * (256.0 + uSquared * (-128.0 + uSquared * (74.0 - 47.0*uSquared)));
+    longitudeRadians = mod((longitudeRadians + PI), TWO_PI);
+    if (longitudeRadians <= 0.0) {
+        longitudeRadians += TWO_PI;
+    }
+    longitudeRadians -= PI;
 
-    float deltaSigma = B * sinSigma * (cos2OmegaM + 1.0/4.0*B * (cosSigma * (-1.0 + 2.0*pow(cos2OmegaM,2.0)) - 1.0/6.0*B*cos2OmegaM*(-3.0+4.0*pow(sinSigma,2.0))*(-3.0+4.0*pow(cos2OmegaM,2.0))));
-    s = b*A*(sigma - deltaSigma);
-    a1 = atan(cos(u2)*sin(lambda), cos(u1)*sin(u2)-sin(u1)*cos(u2)*cos(lambda));
-    a2 = atan(cos(u1)*sin(lambda), -sin(u1)*cos(u2)+cos(u1)*sin(u2)*cos(lambda));
+    coords.latitude = radianAngle(latitudeRadians);
+    coords.longitude = radianAngle(longitudeRadians);
+}
 
-    return true;
+struct Geodedic {
+    float s;
+    Angle a1;
+    Angle a2;
+    bool didGetGoodEstimate;
+};
+
+const float tolerance = pow(10.0, -13.0);
+
+Geodedic vincenty(Ellipsoid ellipsoid, GlobalCoordinates start, GlobalCoordinates end) {
+    float a = ellipsoid.semiMajorAxisMeters;
+    float b = ellipsoid.semiMinorAxisMeters;
+    float f = ellipsoid.flattening;
+
+    float phi1 = start.latitude.radians;
+    float lambda1 = start.longitude.radians;
+    float phi2 = end.latitude.radians;
+    float lambda2 = end.longitude.radians;
+
+    float a2 = a * a;
+    float b2 = b * b;
+    float a2b2b2 = (a2 - b2) / b2;
+
+    float omega = lambda2 - lambda1;
+
+    float tanphi1 = tan(phi1);
+    float tanU1 = (1.0 - f) * tanphi1;
+    float U1 = atan(tanU1);
+    float sinU1 = sin(U1);
+    float cosU1 = cos(U1);
+
+    float tanphi2 = tan(phi2);
+    float tanU2 = (1.0 - f) * tanphi2;
+    float U2 = atan(tanU2);
+    float sinU2 = sin(U2);
+    float cosU2 = cos(U2);
+
+    float sinU1sinU2 = sinU1 * sinU2;
+    float cosU1sinU2 = cosU1 * sinU2;
+    float sinU1cosU2 = sinU1 * cosU2;
+    float cosU1cosU2 = cosU1 * cosU2;
+
+    // equ. 13
+    float lambda = omega;
+
+    // intermediates to compute 's'
+    float A = 0.0;
+    float B = 0.0;
+    float sigma = 0.0;
+    float deltasigma = 0.0;
+    float lambda0;
+    bool converged = false;
+
+    for (int i = 0; i < 20; i++) {
+        lambda0 = lambda;
+        float sinlambda = sin(lambda);
+        float coslambda = cos(lambda);
+        // equ. 14
+        float cosU1sinU2_sinU2cosU2coslambda = cosU1sinU2 - sinU1cosU2 * coslambda;
+        float sin2sigma = (cosU2 * sinlambda * cosU2 * sinlambda) + (cosU1sinU2_sinU2cosU2coslambda * cosU1sinU2_sinU2cosU2coslambda);
+        float sinsigma = sqrt(sin2sigma);
+
+        // equ. 15
+        float cossigma = sinU1sinU2 + (cosU1cosU2 * coslambda);
+
+        // equ. 16
+        sigma = atan(sinsigma, cossigma);
+
+        // equ. 17 - careful, sin2sigma might be almost 0
+        float sinalpha = (sin2sigma == 0.0) ? 0.0 : cosU1cosU2 * sinlambda / sinsigma;
+        float alpha = asin(sinalpha);
+        float cosalpha = cos(alpha);
+        float cos2alpha = cosalpha * cosalpha;
+
+        // equ. 18 - careful, cos2alpha might be almost 0
+        float cos2sigmam = (cos2alpha == 0.0) ? 0.0 : cossigma - 2.0 * sinU1sinU2 / cos2alpha;
+        float u2 = cos2alpha * a2b2b2;
+        float cos2sigmam2 = cos2sigmam * cos2sigmam;
+
+        // equ. 3
+        A = 1.0 + u2 / 16384.0 * (4096.0 + u2 * (-768.0 + u2 * (320.0 - 175.0 * u2)));
+        // equ. 4
+        B = u2 / 1024.0 * (256.0 + u2 * (-128.0 + u2 * (74.0 - 47.0 * u2)));
+        // equ. 6
+        deltasigma = B * sinsigma * (cos2sigmam + B / 4.0 * (cossigma * (-1.0 + 2.0 * cos2sigmam2) - B / 6.0 * cos2sigmam * (-3.0 + 4.0 * sin2sigma) * (-3.0 + 4.0 * cos2sigmam2)));
+        // equ. 10
+        float C = f / 16.0 * cos2alpha * (4.0 + f * (4.0 - 3.0 * cos2alpha));
+        // equ. 11 (modified)
+        lambda = omega + (1.0 - C) * f * sinalpha * (sigma + C * sinsigma * (cos2sigmam + C * cossigma * (-1.0 + 2.0 * cos2sigmam2)));
+
+        if (i < 2) {
+            continue;
+        }
+
+        float change = abs((lambda - lambda0) / lambda);
+        if (change < tolerance) {
+            converged = true;
+            break;
+        }
+
+        // equ. 19
+        float s = b * A * (sigma - deltasigma);
+        Angle alpha1;
+        Angle alpha2;
+
+        bool didGetGoodEstimate = true;
+
+        // didn't converge? must be N/S
+        if (!converged) {
+            if (phi1 > phi2) {
+                alpha1 = degreeAngle(180.0);
+                alpha2 = degreeAngle(0.0);
+            } else if (phi1 < phi2) {
+                alpha1 = degreeAngle(0.0);
+                alpha2 = degreeAngle(180.0);
+            } else {
+                alpha1 = Angle(0.0 / 0.0); // NaN
+                alpha2 = Angle(0.0 / 0.0); // NaN
+                didGetGoodEstimate = false;
+            }
+        } else {
+            float radians;
+            // equ. 20
+            radians = atan(cosU2 * sin(lambda), (cosU1sinU2 - sinU1cosU2 * cos(lambda)));
+            if (radians < 0.0) {
+                radians += TWO_PI;
+            }
+            alpha1 = radianAngle(radians);
+
+            radians = atan(cosU1 * sin(lambda), (-sinU1cosU2 + cosU1sinU2 * cos(lambda))) + PI;
+            if (radians < 0.0) {
+                radians += TWO_PI;
+            }
+            alpha2 = radianAngle(radians);
+        }
+
+        if (alpha1.radians >= TWO_PI) {
+            alpha1 = radianAngle(alpha1.radians - TWO_PI);
+        }
+        if (alpha2.radians >= TWO_PI) {
+            alpha2 = radianAngle(alpha2.radians - TWO_PI);
+        }
+
+        return Geodedic(s, alpha1, alpha2, didGetGoodEstimate);
+    }
 }
 
 void main() {
+    Ellipsoid WGS84 = fromAAndInverseF(6378137.0, 298.257223563);
     float lat;
     float lng;
     xyToLngLat(raw_pos.x, raw_pos.y, lat, lng);
@@ -76,17 +236,25 @@ void main() {
     float a1;
     float a2;
     float s;
-    ;
 
     // should be 43.58777778
     // 88 > x > 89
     // >40.0
     float delta = 0.01;
+
+    GlobalCoordinates radar = GlobalCoordinates(degreeAngle(radarLat), degreeAngle(radarLng));
+    canonicalizeGlobalCoordinates(radar);
+    GlobalCoordinates
+    samplePoint = GlobalCoordinates(degreeAngle(lat), degreeAngle(lng));
+    canonicalizeGlobalCoordinates(samplePoint);
+
+    Geodedic vincentyResult = vincenty(WGS84, radar, samplePoint);
+
     //
     // abs(lat-43.5877) <delta && abs(lng+96.72944444)<delta
-    if (vincenty(radians(radarLat), radians(lat), radians(radarLng), radians(lng), a1, a2, s)) {
+    if (vincentyResult.didGetGoodEstimate) {
         fragColor = vec4(0.0, 1.0, 0.0, 0.5);
     } else {
         fragColor = vec4(1.0, 0.0, 0.0, 0.5);
     }
-}
\ No newline at end of file
+}
