90 lines
2.7 KiB
C
90 lines
2.7 KiB
C
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/*
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Apophysis Plugin
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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typedef struct
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{
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double barycentroid_a, barycentroid_b, barycentroid_c, barycentroid_d;
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double a, b, c, d;
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} Variables;
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#include "apoplugin.h"
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APO_PLUGIN("barycentroid");
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APO_VARIABLES(
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VAR_REAL(barycentroid_a, 1.0),
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VAR_REAL(barycentroid_b, 0.0),
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VAR_REAL(barycentroid_c, 0.0),
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VAR_REAL(barycentroid_d, 1.0)
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);
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int PluginVarPrepare(Variation* vp)
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{
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// alias
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VAR(a) = VAR(barycentroid_a);
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VAR(b) = VAR(barycentroid_b);
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VAR(c) = VAR(barycentroid_c);
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VAR(d) = VAR(barycentroid_d);
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return TRUE;
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}
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inline double sgn(double v) { return v < 0 ? -1 : v > 0 ? 1 : 0; }
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int PluginVarCalc(Variation* vp)
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{
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// helpers
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/* The code is supposed to be fast and you all can read it so I dont
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create those aliases for readability in actual code:
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v0x = VAR(a)
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v0y = VAR(b)
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v1x = VAR(c)
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v1y = VAR(d)
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v2x = FTx
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v2y = FTy
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*/
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// compute dot products
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double dot00 = VAR(a) * VAR(a) + VAR(b) * VAR(b); // v0 * v0
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double dot01 = VAR(a) * VAR(c) + VAR(b) * VAR(d); // v0 * v1
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double dot02 = VAR(a) * FTx + VAR(b) * FTy; // v0 * v2
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double dot11 = VAR(c) * VAR(c) + VAR(d) * VAR(d); // v1 * v1
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double dot12 = VAR(c) * FTx + VAR(d) * FTy; // v1 * v2
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// compute inverse denomiator
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double invDenom = 1 / (dot00 * dot11 - dot01 * dot01);
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/* now we can pull [u,v] as the barycentric coordinates of the point
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P in the triangle [A, B, C]
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*/
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double u = (dot11 * dot02 - dot01 * dot12) * invDenom;
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double v = (dot00 * dot12 - dot01 * dot02) * invDenom;
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// now combine with input
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double um = sqrt(sqr(u) + sqr(FTx)) * sgn(u);
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double vm = sqrt(sqr(v) + sqr(FTy)) * sgn(v);
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FPx += VVAR * um;
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FPy += VVAR * vm;
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FPz += VVAR * FTz; // just pass
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return TRUE;
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}
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