ПР @coding_with_kangaroo
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Прогаем с кенгурой Тут в соседнем чате скинули статью про настроечные таблицы и я вспомнил, что давно когда-то пробовал их использовать для реверсинжинирига цветокоррекций и эффектов, но они справлялись не очень (не для того их делали), поэтому пришлось сделать свою. Из минусов…
struct AstigCtx {
float2 e_r; // radial unit in uv metric
float2 e_t; // tangential unit (perp)
float s_r; // radial scale
float s_t; // tangential scale
float rhoN; // normalized field height (0 center .. 1 edge)
};
inline AstigCtx astigSetup(float2 uv, constant Parameters& P) {
AstigCtx C;
float ar = P.invSize.y / P.invSize.x; // width/height
float2 oc = P.opticalCenter;
float2 df = uv - oc;
float2 dfIso = float2(df.x * ar, df.y);
float rhoN = clamp(length(dfIso) * 2.0f, 0.0f, 1.0f);
float2 rIso = (length(dfIso) > 1e-6f) ? normalize(dfIso) : float2(1.0f, 0.0f);
float2 e_r = normalize(float2(rIso.x / ar, rIso.y));
float2 e_t = float2(-e_r.y, e_r.x);
float mag = fabs(P.astigK) * (rhoN * rhoN);
float a = 1.0f + mag;
float s_r = (P.astigK >= 0.0f) ? (1.0f / a) : a;
float s_t = (P.astigK >= 0.0f) ? a : (1.0f / a);
C.e_r = e_r;
C.e_t = e_t;
C.s_r = s_r;
C.s_t = s_t;
C.rhoN = rhoN;
return C;
}
inline float2 comaApply(float2 d, AstigCtx C, float comaK) {
if (fabs(comaK) < 1e-6f) return d;
// Project onto radial/tangential axes
float dr = dot(d, C.e_r);
float dt = dot(d, C.e_t);
// Magnitude grows ~ rho^3 across the field (third-order behavior)
float mag = comaK * (C.rhoN * C.rhoN * C.rhoN);
// Quadratic skew in pupil coordinates → "comet" shape in image PSF
float2 delta = ( (dr*dr - 0.5f*dt*dt) * C.e_r
+ (dr*dt) * C.e_t );
return d + mag * delta;
}
struct AstigCtx {
float2 e_r;
float2 e_t;
float s_r;
float s_t;
};
struct Parameters {
float2 invSize;
float2 opticalCenter;
float astigK;
};
inline AstigCtx astigSetup(float2 uv, Parameters params) {
AstigCtx C;
float ar = params.invSize.y / params.invSize.x;
float2 df = uv - params.opticalCenter;
float2 dfIso= float2(df.x * ar, df.y);
float rhoN = clamp(length(dfIso) * 2.0f, 0.0f, 1.0f);
float2 rIso = (length(dfIso) > 1e-6f) ? normalize(dfIso) : float2(1.0f, 0.0f);
C.e_r = normalize(float2(rIso.x / ar, rIso.y));
C.e_t = float2(-C.e_r.y, C.e_r.x);
float mag = fabs(params.astigK) * (rhoN * rhoN);
float a = 1.0f + mag;
C.s_r = (params.astigK >= 0.0f) ? (1.0f / a) : a;
C.s_t = (params.astigK >= 0.0f) ? a : (1.0f / a);
return C;
}
inline float2 astigApply(float2 d, AstigCtx C) {
float dr = dot(d, C.e_r);
float dt = dot(d, C.e_t);
return dr * C.s_r * C.e_r + dt * C.s_t * C.e_t;
}
// Regular n-gon aperture test (inscribed in unit circle). blades<3 → circle (always inside).
inline bool insideAperture(float2 d, int blades) {
if (blades < 3) return true; // circle
float N = float(blades);
// polar angle
float a = atan2(d.y, d.x);
// sector size and half-sector
float sector = 2.0f * M_PI_F / N;
float halfSec = 0.5f * sector;
// wrap angle to [0, sector)
float m = fmod(a + M_PI_F, sector);
if (m < 0.0f) m += sector;
// offset to nearest edge normal (in [-half, half])
float delta = m - halfSec;
// allowed radius along this direction for polygon with circumradius=1
float rAllowed = cos(M_PI_F / N) / max(cos(delta), 1e-4f);
float r = length(d);
return r <= rAllowed;
}
