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precision problem, take 2 (partially) #9

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Dec 19, 2021
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precision problem, take 2 (partially) #9

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11 changes: 9 additions & 2 deletions src/shader.frag
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,7 @@ uniform sampler2D uTexture;
// const float twoPiOnPhi = kTau/kPhi;
// const float phiMinusOne = kPhi-1.;
// const float r = .8;
// const float by2P32 = 1./4294967296.;

const float sqrt5 = 2.23606797749979;
const float PI = 3.141592653589793;
Expand All @@ -36,6 +37,7 @@ const float byLogPhiPlusOne = 0.7202100452062783;
const float twoPiOnPhi = 3.8832220774509327;
const float phiMinusOne = .618033988749895;
const float r = .8;
const float by2P32 = 2.3283064365386963e-10;

float byDots = 1./dots;

Expand Down Expand Up @@ -72,8 +74,13 @@ vec3 nearestFibonacciLattice(vec3 p, out float m) {
float idx = dot(f, c + o);
if (idx > dots) continue;

float v = idx / kPhi;
float theta = (v - floor(v/3000.)*3000.)*kTau;
// float v = idx / kPhi;
// float theta = fract(v) * kTau;

int iFracV = int(idx) * 2654435769; // signed be like nearest-to-zero fmod
float fracV = float(iFracV) * by2P32;
float theta = fracV * kTau;

float cosphi = 1. - 2. * idx * byDots;
float sinphi = sqrt(1. - cosphi * cosphi);
vec3 sample = vec3(cos(theta) * sinphi, sin(theta) * sinphi, cosphi);
Expand Down