From 344fa08dbbc1370eee0e73fc1c1ec427f47d2ff3 Mon Sep 17 00:00:00 2001
From: vini <vini@jozz.com>
Date: Sun, 19 Jul 2026 14:28:43 -0300
Subject: [PATCH] Prevent distorted constellation artwork

---
 plugin/contents/ui/dancer.html | 64 ++++++++++++++++++++++++----------
 1 file changed, 45 insertions(+), 19 deletions(-)

diff --git a/plugin/contents/ui/dancer.html b/plugin/contents/ui/dancer.html
index d94cba8..c273192 100644
--- a/plugin/contents/ui/dancer.html
+++ b/plugin/contents/ui/dancer.html
@@ -1461,26 +1461,28 @@ function renderMilkyWay(lstDeg, glareOn) {
   return true;
 }
 
-/* Resolve a transformação afim que prende três pixels da ilustração às suas
-   três estrelas Hipparcos projetadas. */
+/* Ajuste de similaridade: aproxima as três âncoras Hipparcos usando apenas
+   translação, rotação e escala uniforme. Diferente de uma transformação
+   afim completa, nunca achata nem alonga a anatomia das ilustrações. */
 function constellationArtTransform(source, target) {
-  const [p1, p2, p3] = source;
-  const [q1, q2, q3] = target;
-  const den = p1[0] * (p2[1] - p3[1]) + p2[0] * (p3[1] - p1[1]) +
-              p3[0] * (p1[1] - p2[1]);
-  if (Math.abs(den) < 1e-6) return null;
-  const solve = (v1, v2, v3) => ({
-    x: (v1 * (p2[1] - p3[1]) + v2 * (p3[1] - p1[1]) +
-        v3 * (p1[1] - p2[1])) / den,
-    y: (v1 * (p3[0] - p2[0]) + v2 * (p1[0] - p3[0]) +
-        v3 * (p2[0] - p1[0])) / den,
-    t: (v1 * (p2[0] * p3[1] - p3[0] * p2[1]) +
-        v2 * (p3[0] * p1[1] - p1[0] * p3[1]) +
-        v3 * (p1[0] * p2[1] - p2[0] * p1[1])) / den,
-  });
-  const x = solve(q1.x, q2.x, q3.x);
-  const y = solve(q1.y, q2.y, q3.y);
-  return [x.x, y.x, x.y, y.y, x.t, y.t];
+  const pc = source.reduce((p, v) => [p[0] + v[0], p[1] + v[1]], [0, 0])
+                   .map(v => v / source.length);
+  const qc = target.reduce((p, v) => [p[0] + v.x, p[1] + v.y], [0, 0])
+                   .map(v => v / target.length);
+  let dot = 0, cross = 0, energy = 0;
+  for (let i = 0; i < source.length; i++) {
+    const px = source[i][0] - pc[0], py = source[i][1] - pc[1];
+    const qx = target[i].x - qc[0], qy = target[i].y - qc[1];
+    dot += px * qx + py * qy;
+    cross += px * qy - py * qx;
+    energy += px * px + py * py;
+  }
+  if (energy < 1e-6) return null;
+  const a = dot / energy;
+  const b = cross / energy;
+  const e = qc[0] - a * pc[0] + b * pc[1];
+  const f = qc[1] - b * pc[0] - a * pc[1];
+  return [a, b, -b, a, e, f];
 }
 
 function drawConstellationArt(c, constellation, lst, W, horizonPx) {
@@ -1498,12 +1500,36 @@ function drawConstellationArt(c, constellation, lst, W, horizonPx) {
     };
   });
   if (target.every(p => p.alt < -8) || target.every(p => p.alt > ALT_TOP + 8)) return;
+  if (!target.some(p => p.alt >= -8 && p.alt <= ALT_TOP + 8 &&
+                        p.x >= -W * 0.15 && p.x <= W * 1.15)) return;
+  const targetXs = target.map(p => p.x);
+  if (Math.max(...targetXs) - Math.min(...targetXs) > W * 0.62) return;
 
   const matrix = constellationArtTransform(
     art.anchors.map(anchor => anchor.pos), target
   );
   if (!matrix || matrix.some(v => !Number.isFinite(v))) return;
 
+  /* Mesmo com escala uniforme, uma âncora próxima da descontinuidade do
+     azimute pode sugerir uma figura gigantesca. Limite visual conservador. */
+  const scale = Math.hypot(matrix[0], matrix[1]);
+  const maxScale = Math.min(
+    W * 0.44 / art.size[0], horizonPx * 0.82 / art.size[1]
+  );
+  if (scale > maxScale) {
+    const sourceCenter = [art.size[0] / 2, art.size[1] / 2];
+    const screenCenter = [
+      matrix[0] * sourceCenter[0] + matrix[2] * sourceCenter[1] + matrix[4],
+      matrix[1] * sourceCenter[0] + matrix[3] * sourceCenter[1] + matrix[5],
+    ];
+    const shrink = maxScale / scale;
+    for (let i = 0; i < 4; i++) matrix[i] *= shrink;
+    matrix[4] = screenCenter[0] - matrix[0] * sourceCenter[0] -
+                matrix[2] * sourceCenter[1];
+    matrix[5] = screenCenter[1] - matrix[1] * sourceCenter[0] -
+                matrix[3] * sourceCenter[1];
+  }
+
   c.save();
   c.beginPath();
   c.rect(0, 0, W, horizonPx);