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CultMath GLSL: regenerate on the merge (cultmath_iv_frustum_ball)

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Regeneration alone (CULTMATH_WRITE_GLSL=1) on Yggdrasil at 8be32a2e: the
lowering of r3's widened iv_frustum_ball, 15 lines. The fixture does not
change. Full suite 286/286 green.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
This commit is contained in:
Meta Vens 2026-10-03 13:36:09 +02:00
commit 7fc91d60aa
1 changed files with 15 additions and 0 deletions
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15
packages/cultmath/shaders/CultMath.glsl
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@ -712,6 +712,21 @@ vec2 cultmath_iv_fbm_ball(vec3 centre, float radius, int octaves, float lacunari
return sum;
}
// A ball (xyz centre, w radius) enclosing every point of every ray of a screen tile over the depth segment
// [z0, z1], warped by at most warp. Camera frame: pinhole at the origin looking down +z, ray (m z, z).
// footprintPerDepth = N / (sqrt(2) f) for an N x N tile at focal length f. The radius is widened by
// (|c|_1 + radius) 2^-20, which covers the ball's own float32 rounding. Derivation in math.Interval.cs.
vec4 cultmath_iv_frustum_ball(vec2 centreSlope, float z0, float z1, float footprintPerDepth, float warp)
{
float zm = (z0 + z1) * 0.5;
float axis = sqrt(centreSlope.x * centreSlope.x + centreSlope.y * centreSlope.y + 1.0);
float cx = centreSlope.x * zm;
float cy = centreSlope.y * zm;
float radius = (z1 - z0) * 0.5 * axis + z1 * footprintPerDepth + warp;
radius += (abs(cx) + abs(cy) + abs(zm) + radius) * 9.5367431640625e-7;
return vec4(cx, cy, zm, radius);
}