Iron's Spells: Light Pollution

1.2.0

Questions, bug reports and suggestions: https://discord.gg/adKfbRDn6V

Nine new spells

• Gargantua — a black hole built from the Kerr geometry rather than drawn as a dark ball with a ring around it. Light is bent by integrating the photon geodesic, so the disk's far side is genuinely lensed into arcs over and under the shadow while the near side crosses as a knife-thin bar, and terrain, sky and your other spells' light bend around it too. The proportions are the published Interstellar figures: the shadow is 2.6 times the horizon, the disk stops at the innermost stable circular orbit, and at roughly 4500 K there is no blue in it anywhere. It arrives at full size, hangs flat above the ground, swallows other spell lights one at a time, and detonates at criticality.
• Cosmic Horseshoe — the gravitational lens SDSS J1148+1930, whose arc the discovery paper measures at about 300 degrees; the missing sixty are what give it its name. The arc is not drawn but solved for, by inverting the lens map at every pixel, so the ring lands where the map is singular, the arc is thin because lensing stretches tangentially and not radially, each star-forming knot appears more than once, and a faint counter-image sits opposite the gap — none of it painted in. Unlike the other lenses here it does not swallow: magnification diverges at the Einstein radius, so the ring is the dangerous part and the interior is somewhere to stand.
• Microquasar — SS 433, whose disk precesses, so the ejecta are drawn out into a corkscrew: every blob keeps the direction it left with while the disk turns on under it. The helix has been imaged in radio, and the standard kinematic model reproduces it from a 160-day precession, a 20 degree cone and a jet speed of 0.26c. The two jets do not match — relativistic beaming makes the one coming toward you brighter and bluer and the one going away dimmer and redder, from the Doppler factor cubed. It is the only spell here dodged by timing rather than distance: the jets sweep, so a safe radius does not stay safe.
• Helix Nebula — NGC 7293, the Eye of God. An expanding shell of cometary knots, each a globule whose star-facing side is being boiled off, leaving a bright head and a tail streaming radially away; about 40,000 have been counted in the real object. Two nested rings seen at an inclination make the eye, and they are different colours because they are different shells — blue-green in doubly ionised oxygen inside, red in hydrogen and nitrogen outside. The hazard travels: distance buys time, not safety, and what matters is when the shell arrives.
• Magnetar — SGR 1806-20, whose 2004 giant flare is the most powerful on record and ionised Earth's upper atmosphere from fifty thousand light years away. Closed dipole loops thread out from the poles, built from r = r0 sin²θ so they are the curves a dipole actually makes, and they wind tighter and shift from cold violet toward white-hot as the field loads. Only the lines discharge — the gaps between them are safe, which makes it the one spell where where you stand matters more than how far away you are. Then the magnetosphere rearranges itself all at once.
• Tidal Disruption — a star pulled apart, and the star is the subject rather than the hole: the tidal field stretches it into one enormously long thin stream that wraps back around and lashes. The flare when the bound debris returns follows the t^(-5/3) fallback law that identifies these events, so the light curve is computed from the physics rather than eased by hand.
• Quasar Jet — one needle out of the nucleus, because at these speeds beaming makes the counter-jet invisible. Straight, not precessing, and the knots racing along it move at the apparent speed relativistic geometry gives: about six times light speed at a Lorentz factor of 10 and 17 degrees, the figure actually tracked for M87. Only the knots hit, so the beam is a matter of timing rather than distance, and it ends in a terminal hotspot inside a diffuse lobe.
• Wolf-Rayet Pinwheel — two hot stars whose colliding winds condense dust into an Archimedean spiral, imaged for real with aperture masking on Keck. Constant pitch, empty space between the arms and dust colours rather than a hot disk, so it cannot be mistaken for a third accretion disk. It rotates rigidly, which means the safe gaps travel: a gap is only safe until the next arm reaches it.
• Crab Nebula — a hollow cage of filaments over a void, with a synchrotron wind nebula inside it driven by the pulsar. The two components are shaded as the different materials they are: sharp knotted line emission in red and green, and a smooth structureless blue-white glow. Unlike the World Tree it is hollow, so it is a trap rather than a radius — outside is safe, the filaments sting, the interior pulses, and leaving means crossing the cage again.

Rendering

• The new effects' strands are real tube geometry rather than camera-facing ribbons. A ribbon has no cross-section, never hides itself, and collapses to nothing wherever the curve happens to point at you — which is why they read as pictures pasted over the world instead of as objects. A tube is round from every angle, its near side occludes its far side, and the highlight moves when you do.
• Strands are shaded per fragment from a real geometric normal, and brighten toward the rim rather than falling off like a lit surface, because they are hot emitting material and not plastic pipe. An eight-sided tube no longer creases at every quad edge either.
• Every effect with something at its middle now draws it. Six of the seven had only their outer structure and nothing inside: jets emerging from empty air, field lines looping around a gap, a nebula with no star in it.
• Those central bodies are real spheres, not billboards — actual geometry with a true normal at every vertex, limb-darkened by the Eddington grey-atmosphere law so the edge sits at 0.4 of the middle, with a granulated surface that turns with the body. A flat quad has no limb, no rotation and no silhouette of its own, so it read as a white circle painted on the sky however carefully it was shaded.
• Gargantua's strongest lensing is finally visible. Rays bent far enough to leave the screen had no scene left to read and quietly faded back to whatever colour was already there, which meant the region just outside the photon ring — where light turns through the largest angles — bent nothing you could see. Those rays now look out at a volumetric star field along the direction gravity actually sent them. It is sampled by world direction, so it behaves as a fixed sky rather than sliding about with the camera, which is the only way lensed starlight reads as lensed. The ring tooltip style shows the same field, so the two agree by construction.
• Crab Nebula filaments are closed loops, so none of them has loose ends hanging in the middle of the shell. Closing them is not the same as making them circles — twenty-two great circles is a wireframe globe, which is the one thing the real remnant does not look like — so each loop weaves out of its own plane instead. The join is genuinely invisible rather than merely short: carrying a reference frame once around one of these loops turns it by as much as fifty degrees, and that turn is spread across every ring instead of being dumped into the closing segment.
• The visible rectangles and hard edges in the new effects are gone. They were not tiling artefacts. Raising the exposure left the falloffs ending well above zero at the quads' own boundaries, so what you could see was the edge of the quad itself.

Gargantua

• It pulls. Creatures are dragged toward it rather than only damaged at range, and projectiles are pulled too; inside the capture radius their motion is taken over outright rather than nudged, so they go in instead of sailing past.

Balance

• Every spell's damage is now a distinct figure. Five spells previously shared the same 30–34% finisher and eight sat between 4% and 6% per tick, which made most of the set feel interchangeable on paper. Totals are unchanged in aggregate — this spreads them out, it does not buff or nerf the mod — and the ladder now follows cooldown, from Silhouette's 3% a second up to Stargrave Singularity's 93% execution. Existing tooltips are updated to match in all three languages. Twenty-four spells, forty-nine damage figures, no two the same.

Fixes

• Fixed a startup crash on AMD graphics cards. Six shaders declared a function named noise3 or noise2, and those are reserved built-in names in the GLSL specification — the built-in returns a different type, so declaring one is an illegal overload. AMD's compiler declares those built-ins and NVIDIA's does not, which is why this only ever affected some machines. Constellation, Second Sun, Singularity, Sky Collapse and Eclipse Severance were all affected; the crash only ever named the first, because loading stopped there.
• A shader that fails to compile no longer takes the game down with it. One bad shader used to be an unrecoverable startup crash; now it is logged, that one effect is skipped, and everything else runs. Driver-specific GLSL differences cannot all be known in advance, so the cost of one has to be a missing effect rather than an unplayable game.
• Fixed effects leaking a shader colour into whatever drew next. Fourteen world renderers each carried their own copy of the same GL state snapshot, and the copies had drifted: seven put the shader colour back and seven did not. Since the central bodies set that colour's alpha as high as 2.0 to pick which layer to draw, anything rendering after one of the seven inherited it. There is now one snapshot, and it restores the colour that was actually there beforehand rather than assuming white.

Presentation

• Spell icons for all nine new spells, drawn from the same geometry the effects use.
• Every new spell has a _show command that stands one up for inspection with a matching _clear: /gargantua_show, /horseshoe_show, /quasar_show, /helix_show, /magnetar_show, /tde_show, /jet_show, /pinwheel_show and /crab_show. Operator-only, and they do no damage.
• The Simplified Chinese text for the Cosmic Horseshoe was written in the classical register, with the 分/釐/毫 fractions that belong to the Literary Chinese file. It now reads as modern Chinese with percentages, like the rest of zh_cn.
• Animated text effects are built in rather than depended on, ported from the author's own dynamic-text mod, so the spell names move without adding a second download. Its toggles live in their own config file.
• Tooltips for this mod's items are styled per spell: the name animates, and every line under it takes that spell's accent colour. The lines below the name are not ours — level, rarity, cast time, mana, cooldown and school all come from Iron's Spells in its own orange, blue, grey and red, which no language file here can reach — so half the box used to clash with the other half.
• Seven optional tooltip styles, all off by default and all switchable in game with /lightpollution frame <style>, or set tooltipStyle in the client config to keep one. Every style is tinted to the spell's own accent, so a tooltip looks like the spell it describes.
  • panel — a rounded panel behind the normal layout, which vanilla still fills in.
  • arcane — takes rendering over: glow rays radiating from behind the box, a centred title, a rule under it.
  • orbit — the spell's own icon drifting behind the panel with ghost copies trailing it.
  • astral — a drifting field of thirty-two points, turning marks at the corners, and a band of light travelling under the title.
  • ring — a tilted ring that passes through the tooltip, with a star field inside the band. The far half is drawn, then the panel, then the near half.
  • sigil — two counter-rotating triangular bands behind the panel, forming a six-pointed figure that never settles.
  • pinwheel — no panel at all: each line becomes a spoke of a slowly turning pinwheel, every glyph placed individually with its own tilt and a wave running along the line. Every style carries a highlight that travels around the outline rather than pulsing in place. Adapted from ArcaneVortex with its author's permission, credited in CREDITS.txt — nine separate renderers there, which shared a vocabulary and mostly differed in which pieces they used.
• Damage from these spells can float above what it hits, in that spell's own colour. Off by default — turn it on with /lightpollution damage on or set floatingDamage in the client config. Damage on one target is accumulated for half a second and shown once as a total: these spells tick rather than landing single hits, and the Crab Nebula alone would otherwise put around forty separate numbers on one target in a single cast.
• Four spells now announce their own turning point, which were all completely silent before: Gargantua's horizon closing, the magnetar's magnetosphere letting go, a tidal disruption's fallback peaking, and the Crab remnant coming apart.