24 lines
1.1 KiB
WebGPU Shading Language
24 lines
1.1 KiB
WebGPU Shading Language
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// RTVolume any-hit shader (runs in TRACE on every candidate sphere hit,
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// because the geometry is registered non-opaque). Punches a spherical
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// checkerboard of holes: for half the cells it returns RT_ANYHIT_IGNORE,
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// so the ray passes straight through and the background / spheres behind
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// show through. Returning RT_ANYHIT_ACCEPT keeps the hit. This is the
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// visible proof the any-hit path runs — with it the spheres are perforated,
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// without it they would be solid.
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fn anyhit_main(ray: RayDesc, hit: HitInfo, payload: ptr<function, Payload>) -> u32 {
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// Object-space hit point on the unit sphere → its normal/direction.
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let posObj = hit.objectRayOrigin + hit.objectRayDirection * hit.t;
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let n = normalize(posObj);
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let PI = 3.14159265;
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let longitude = atan2(n.z, n.x); // [-PI, PI]
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let latitude = asin(clamp(n.y, -1.0, 1.0)); // [-PI/2, PI/2]
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let cu = i32(floor((longitude + PI) / PI * 6.0));
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let cv = i32(floor((latitude + PI * 0.5) / PI * 6.0));
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if (((cu + cv) & 1) == 0) {
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return RT_ANYHIT_IGNORE; // cut-out cell — see through
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}
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return RT_ANYHIT_ACCEPT;
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}
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