102 lines
2.7 KiB
C
102 lines
2.7 KiB
C
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typedef struct
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{
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// variables
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double ripple_frequency,
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ripple_velocity,
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ripple_amplitude,
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ripple_centerx,
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ripple_centery,
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ripple_phase,
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ripple_scale;
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// private stuff
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double f, a, p, s, is,
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vxp, pxa, pixa;
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} Variables;
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#define _USE_MATH_DEFINES
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#include "apoplugin.h"
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APO_PLUGIN("ripple");
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APO_VARIABLES(
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// wave function frequency
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VAR_REAL(ripple_frequency, 2.0),
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// wave velocity
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VAR_REAL(ripple_velocity, 1.0),
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// wave amplitude
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VAR_REAL(ripple_amplitude, 0.5),
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// origin of the ripple (x,y)
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VAR_REAL(ripple_centerx, 0.0),
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VAR_REAL(ripple_centery, 0.0),
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// wave phase / interpolation coefficient
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VAR_REAL(ripple_phase, 0.0),
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// ripple scale
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VAR_REAL(ripple_scale, 1.0)
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);
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int PluginVarPrepare(Variation* vp)
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{
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// some variables are settled in another range for edit comfort
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// - transform them
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VAR(f) = VAR(ripple_frequency) * 5;
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VAR(a) = VAR(ripple_amplitude) * 0.01;
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VAR(p) = VAR(ripple_phase) * M_2PI - M_PI;
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// scale must not be zero
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VAR(s) = VAR(ripple_scale) == 0 ? EPS : VAR(ripple_scale);
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// we will need the inverse scale
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VAR(is) = 1 / VAR(s);
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// pre-multiply velocity+phase, phase+amplitude and (PI-phase)+amplitude
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VAR(vxp) = VAR(ripple_velocity) * VAR(p);
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VAR(pxa) = VAR(p) * VAR(a);
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VAR(pixa) = (M_PI - VAR(p)) * VAR(a);
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// done
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return TRUE;
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}
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inline double lerp(double a, double b, double p) { return a + (b - a) * p; }
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int PluginVarCalc(Variation* vp)
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{
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//align input x, y to given center and multiply with scale
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double x = (FTx * VAR(s)) - VAR(ripple_centerx),
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y = (FTy * VAR(s)) + VAR(ripple_centery);
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// calculate distance from center but constrain it to EPS
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double d = MAX(EPS, sqrt(sqr(x) * sqr(y)));
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// normalize (x,y)
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double nx = x / d,
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ny = y / d;
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// calculate cosine wave with given frequency, velocity
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// and phase based on the distance to center
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double wave = cos(VAR(f) * d - VAR(vxp));
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// calculate the wave offsets
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double d1 = wave * VAR(pxa) + d,
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d2 = wave * VAR(pixa) + d;
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// we got two offsets, so we also got two new positions (u,v)
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double u1 = (VAR(ripple_centerx) + nx * d1),
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v1 = (-VAR(ripple_centery) + ny * d1);
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double u2 = (VAR(ripple_centerx) + nx * d2),
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v2 = (-VAR(ripple_centery) + ny * d2);
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// interpolate the two positions by the given phase and
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// invert the multiplication with scale from before
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FPx = VVAR * (lerp(u1, u2, VAR(p))) * VAR(is);
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FPy = VVAR * (lerp(v1, v2, VAR(p))) * VAR(is);
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// done
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return TRUE;
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}
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