xfy
5fa2621e6a
The whole-file #import "file.wgsl" form (without ::) does not reliably bring functions into scope in naga_oil/Bevy 0.19 — the renderer was failing at runtime with 'no definition in scope for identifier: ray_direction' (and rot_x, deriv, etc.), producing a blank screen despite 'cargo build' passing (shaders aren't compile-checked at build time). Fix: add #define_import_path to each module file and import symbols explicitly via namespace::name (the canonical Bevy pattern from the shader_material_2d example). Verified the full shader pipeline compiles and runs at runtime with zero WGSL errors. This was a pre-existing bug masked by incomplete runtime verification in earlier tasks; it is NOT specific to Task 15's grid work. All earlier visual features (shadow, Doppler disk, Einstein halo, stars, planets, grid) now actually render.
52 lines
2.1 KiB
WebGPU Shading Language
52 lines
2.1 KiB
WebGPU Shading Language
// Flamm's paraboloid embedding: z(r) = 2*sqrt(Rs*(r - Rs)), opens DOWNWARD
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// (negative y in disk-local space). Dips below the disk toward the center —
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// the classic gravity-well visualization. Traced through curved spacetime, so
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// grid lines near the hole bend dramatically.
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#define_import_path singularity::grid
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fn flamm_depth(r: f32) -> f32 {
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if (r <= uniforms.rs) { return 0.0; }
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return -2.0 * sqrt(uniforms.rs * (r - uniforms.rs));
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}
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// Returns additive grid color if the segment prev->cur crosses the Flamm
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// paraboloid surface; returns black otherwise. `prev`/`cur` are disk-local.
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fn grid_hit(prev: vec3<f32>, cur: vec3<f32>) -> vec3<f32> {
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// Sample the paraboloid at the segment endpoints; if the segment crosses it,
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// find an approximate crossing by sampling.
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let r0 = length(vec2<f32>(prev.x, prev.z));
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let r1 = length(vec2<f32>(cur.x, cur.z));
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let z0_surf = flamm_depth(r0);
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let z1_surf = flamm_depth(r1);
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// Did the ray's y cross the surface y between endpoints?
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if ((prev.y - z0_surf) * (cur.y - z1_surf) > 0.0) {
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return vec3<f32>(0.0);
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}
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// Crossing: linear-search for the crossing point.
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var hit = vec3<f32>(0.0);
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var found = false;
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for (var s: i32 = 0; s < 8; s = s + 1) {
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let f = f32(s + 1) / 8.0;
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let p = mix(prev, cur, vec3<f32>(f));
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let r = length(vec2<f32>(p.x, p.z));
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let surf = flamm_depth(r);
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if (abs(p.y - surf) < 0.3) {
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hit = p;
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found = true;
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break;
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}
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}
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if (!found) { return vec3<f32>(0.0); }
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// Polar grid pattern from (r, phi).
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let r = length(vec2<f32>(hit.x, hit.z));
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let phi = atan2(hit.z, hit.x);
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let ring = smoothstep(0.06, 0.0, abs(fract(r * uniforms.grid_density * 0.5) - 0.5));
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let spoke = smoothstep(0.04, 0.0, abs(fract(phi * 6.0 / 6.283185) - 0.5));
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let grid = max(ring, spoke);
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// Fade with depth so the grid reads as "below" the hole.
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let fade = smoothstep(-15.0, -1.0, hit.y);
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let col = vec3<f32>(0.15, 0.3, 0.6) * grid * fade;
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return col * 0.5; // additive, low intensity
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}
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