metaheavens/spaceship - Forgejo

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Make the lunar backdrop cheap: 3x3 field, then bake and tile it (#68) The crater shader ran on every pixel of a fullscreen rect every frame and was by far the most expensive thing in the surface scene. Nothing else came close: RockField keeps 14 rocks alive, Rock/Ship/Enemy already avoid per-frame queue_redraw() for transform-only changes, and LunarBackground.gd is a handful of scalar ops. Three reductions to the field itself: - 5x5 -> 3x3 neighbour scan. That width was never the geometric answer; it was insurance against craters seen clipping at cell boundaries on-device, i.e. a crater reaching past its nominal radius because a hash returned a value outside [0,1] and extrapolated mix(). Clamping the crater CENTRE into its own cell, alongside the radius clamp already there, bounds the reach whatever the hash returns - so a crater two cells out is >= 1.0 cells away, a normalized distance of >= 2.63, past every threshold the shading reacts to (the last saturates at 1.15). The outer ring provably cannot change a pixel. This removes the clipping bug's cause instead of hiding it behind 16 extra samples. - One hash42 per cell instead of hash21 twice plus hash22, decorrelating on output lanes rather than input offsets. - Squared distances in the loop, square-rooted twice at the end rather than once per sample. Measured with the new tests/profile_shader.sh, above softpipe's own ~657ms fullscreen floor: 9482ms -> 405ms of shader work, a 23x reduction. Then the larger change: the field is a fixed function of world position, so every frame recomputed an identical answer. It is now made periodic (the cell index is wrapped before hashing, which makes a Worley field tile exactly rather than merely blend), baked once at load into one tile, and scrolled with repeat wrapping by lunar_tiled.gdshader - one texture fetch per pixel. Two honest costs: the field repeats every 7040 world units, and a fixed-resolution tile softens when zoomed past 1:1. Lunar regolith is forgiving of both, having no landmarks and being smooth gradients already. The bake waits a frame and asks the material whether it actually samples a field_texture, so a gas giant - which swaps in its own background shader (#51) - does not pay for a 2048-square tile it will never read. Headless runs skip it entirely, having nothing to rasterize. tests/test_lunar_field.gd guards the reasoning, since a fragment shader cannot be asserted on directly: the premises are still in the source, the worst-case ring-2 geometry stays clear of every threshold independent of the hash, a 3x3 and a 5x5 scan render identically over 4000 sampled points, the field repeats exactly in both axes, and the miss sentinel still cannot overflow mediump into +Inf and then NaN. test_surface_profiles.gd asserted "a rocky landing leaves the background alone" by naming lunar_surface.gdshader; it now reads the shader from the scene, which is the property it actually cares about. PlanetSurface.tscn's edit also carries the planet-name relocation described in the HUD commit - same scene file, so the two cannot be split. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

2026-08-17 23:20:14 +02:00

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