Scale the system view to the system it is showing

Star size, planet marker size and camera distance were all fixed constants in AU, tuned against the solar system's 30 AU span. Real systems span four orders of magnitude, and the fixed values served only the wide end. Measured across the 370 systems that draw planets: - 170 had their innermost orbit inside the 0.2 AU star sphere, and for 107 of those every orbit was inside it, so the system rendered as a lone sphere. - 193 were framed from the 3 AU distance floor — for TRAPPIST-1 that is 48x the width of the entire system, reducing it to a cluster of specks. - Planet markers were effectively a flat 0.09 AU, since almost every body clamps to the maximum. Inside Gl 357's 0.204 AU system that is wider than the orbits themselves: one planet swallowed the whole view. All three are now derived from the system's own measurements. The star is a fraction of the innermost orbit, so it can never reach the closest one. The camera is a multiple of the outermost orbit, so everything fits. Markers scale with the span against the solar system as the reference, so the constants that were tuned by eye keep their meaning. Because star, markers and camera all scale together, a compact system now looks like a wide one — same apparent star, same legible spread of orbits. Gl 357 is the case that motivated this. It gained three planets in the previous commit and still rendered as a bare star, because all three orbits were inside the star sphere. It now shows its star and all three orbits. The renderer measures the span before building anything, since markers are sized against it as they are created, which also removes the reduce over tracked bodies that used to compute it afterwards. The star sphere is rebuilt per system rather than shared, so its geometry is now disposed on each transition. Sol is deliberately unchanged: its innermost orbit is Mercury at 0.387 AU, so the star lands just under the old fixed radius, and the reference span makes the marker scale factor 1. Verified side by side. Tests: 206 passing, up from 199. Verified in a real browser against both ends of the range — Gl 357 at 0.2 AU and Sol at 30 AU. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01WaySiNst4HhDXBHnMy8p5G
2026-08-04 11:43:29 +00:00
parent f241b093eb
commit f2c77fb5ad
4 changed files with 276 additions and 28 deletions
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+import { describe, expect, it } from 'vitest';
+
+import { bodyMarkerRadiusAu, DEFAULT_STAR_MARKER_RADIUS_AU, starMarkerRadiusAu, systemFramingDistanceAu } from './system-framing';
+
+/** Real systems spanning the range the view has to cope with. */
+const TRAPPIST_1 = { innermost: 0.01154, outermost: 0.06189 };
+const GL_357 = { innermost: 0.035, outermost: 0.204 };
+const SOLAR = { innermost: 0.387, outermost: 30.07 };
+
+describe('starMarkerRadiusAu', () => {
+  it('never reaches the innermost orbit', () => {
+    for (const { innermost } of [TRAPPIST_1, GL_357, SOLAR]) {
+      expect(starMarkerRadiusAu(innermost)).toBeLessThan(innermost);
+    }
+  });
+
+  it('shrinks to fit a compact system whose orbits were all inside the old fixed radius', () => {
+    // Every TRAPPIST-1 orbit is inside 0.2 AU, so the star used to swallow the entire system.
+    expect(starMarkerRadiusAu(TRAPPIST_1.innermost)).toBeLessThan(TRAPPIST_1.outermost);
+    expect(starMarkerRadiusAu(GL_357.innermost)).toBeLessThan(GL_357.outermost);
+  });
+
+  it('never grows beyond the default, however wide the system', () => {
+    expect(starMarkerRadiusAu(SOLAR.innermost)).toBeLessThanOrEqual(DEFAULT_STAR_MARKER_RADIUS_AU);
+    expect(starMarkerRadiusAu(500)).toBe(DEFAULT_STAR_MARKER_RADIUS_AU);
+  });
+
+  it('scales in proportion to the innermost orbit', () => {
+    expect(starMarkerRadiusAu(0.02) / starMarkerRadiusAu(0.01)).toBeCloseTo(2, 9);
+  });
+
+  it('falls back to the default when there are no planets to scale against', () => {
+    for (const innermost of [0, -1, Number.NaN, Number.POSITIVE_INFINITY]) {
+      expect(starMarkerRadiusAu(innermost)).toBe(DEFAULT_STAR_MARKER_RADIUS_AU);
+    }
+  });
+
+  it('stays positive for an extremely tight orbit', () => {
+    expect(starMarkerRadiusAu(0.0001)).toBeGreaterThan(0);
+  });
+});
+
+describe('systemFramingDistanceAu', () => {
+  it('fits the whole system in view', () => {
+    for (const { outermost } of [TRAPPIST_1, GL_357, SOLAR]) {
+      expect(systemFramingDistanceAu(outermost)).toBeGreaterThan(outermost);
+    }
+  });
+
+  it('closes right in on a compact system instead of hanging back at a fixed floor', () => {
+    // The old floor was 3 AU — some 48x the width of the entire TRAPPIST-1 system.
+    expect(systemFramingDistanceAu(TRAPPIST_1.outermost)).toBeLessThan(1);
+    expect(systemFramingDistanceAu(GL_357.outermost)).toBeLessThan(1);
+  });
+
+  it('scales in proportion to the outermost orbit', () => {
+    expect(systemFramingDistanceAu(0.2) / systemFramingDistanceAu(0.1)).toBeCloseTo(2, 9);
+  });
+
+  it('caps the distance so a far-flung companion cannot shrink the star to nothing', () => {
+    expect(systemFramingDistanceAu(1000)).toBe(systemFramingDistanceAu(5000));
+    expect(systemFramingDistanceAu(SOLAR.outermost)).toBeLessThanOrEqual(80);
+  });
+
+  it('stays outside the orbit controls minimum distance', () => {
+    // Framing closer than the controls allow would be clamped straight back out again.
+    expect(systemFramingDistanceAu(0.00001)).toBeGreaterThanOrEqual(0.05);
+  });
+
+  it('uses a sensible default for a star with no known planets', () => {
+    for (const outermost of [0, -1, Number.NaN]) {
+      expect(systemFramingDistanceAu(outermost)).toBe(3);
+    }
+  });
+});
+
+describe('star and framing together', () => {
+  it('gives compact and wide systems a comparable apparent star size', () => {
+    // Both scale with the system, so the star subtends a similar angle either way — the point
+    // of deriving them from the same measurements rather than fixing them.
+    const apparent = ({ innermost, outermost }: { innermost: number; outermost: number }) =>
+      starMarkerRadiusAu(innermost) / systemFramingDistanceAu(outermost);
+
+    const compact = apparent(TRAPPIST_1);
+    const midRange = apparent(GL_357);
+
+    expect(compact).toBeGreaterThan(0);
+    expect(compact / midRange).toBeGreaterThan(0.25);
+    expect(compact / midRange).toBeLessThan(4);
+  });
+
+  it('always leaves the innermost orbit outside the star, at every scale', () => {
+    for (const innermost of [0.005, 0.01, 0.05, 0.2, 1, 5, 40]) {
+      expect(starMarkerRadiusAu(innermost)).toBeLessThan(innermost);
+    }
+  });
+});
+
+describe('bodyMarkerRadiusAu', () => {
+  const EARTH_RADIUS_KM = 6371;
+  const SOLAR_SPAN_AU = 30.07;
+
+  it('scales in proportion to the system span', () => {
+    const wide = bodyMarkerRadiusAu(EARTH_RADIUS_KM, SOLAR_SPAN_AU);
+    const compact = bodyMarkerRadiusAu(EARTH_RADIUS_KM, SOLAR_SPAN_AU / 100);
+
+    expect(compact / wide).toBeCloseTo(0.01, 6);
+  });
+
+  it('keeps a marker far smaller than the orbits it sits on, at any scale', () => {
+    // A fixed 0.09 AU marker inside Gl 357's 0.204 AU system was wider than the orbits, so one
+    // planet swallowed the whole view.
+    for (const span of [0.06, 0.204, 1, 30.07, 800]) {
+      expect(bodyMarkerRadiusAu(EARTH_RADIUS_KM, span)).toBeLessThan(span / 5);
+    }
+  });
+
+  it('gives compact and wide systems the same apparent marker size', () => {
+    const apparent = (span: number) => bodyMarkerRadiusAu(EARTH_RADIUS_KM, span) / systemFramingDistanceAu(span);
+
+    expect(apparent(0.204)).toBeCloseTo(apparent(10), 6);
+  });
+
+  it('still renders a bigger body as a bigger marker', () => {
+    const jupiter = bodyMarkerRadiusAu(69911, SOLAR_SPAN_AU);
+    const pluto = bodyMarkerRadiusAu(1188, SOLAR_SPAN_AU);
+
+    expect(jupiter).toBeGreaterThan(pluto);
+  });
+
+  it('falls back to the smallest marker for a body with no known radius', () => {
+    const unknown = bodyMarkerRadiusAu(undefined, SOLAR_SPAN_AU);
+    const pluto = bodyMarkerRadiusAu(1188, SOLAR_SPAN_AU);
+
+    expect(unknown).toBeGreaterThan(0);
+    expect(unknown).toBeLessThanOrEqual(pluto);
+  });
+
+  it('treats a missing span as the reference scale rather than collapsing to zero', () => {
+    for (const span of [0, -5, Number.NaN]) {
+      expect(bodyMarkerRadiusAu(EARTH_RADIUS_KM, span)).toBeGreaterThan(0);
+    }
+  });
+
+  it('leaves the solar system essentially as it was before scaling', () => {
+    // The constants were tuned at this span, so the scale factor here is ~1.
+    expect(bodyMarkerRadiusAu(EARTH_RADIUS_KM, SOLAR_SPAN_AU)).toBeCloseTo(0.09, 2);
+  });
+});