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24 lines
881 B
C++
24 lines
881 B
C++
#include "CatmullRom.h"
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USING_NS_BF;
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PointF Beefy::CatmullRomEvaluate(PointF &p0, PointF &p1, PointF &p2, PointF &p3, float tension, float t)
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{
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float t2 = t * t;
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float t3 = t2 * t;
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/*
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* Formula: s(-ttt + 2tt - t)P1 + s(-ttt + tt)P2 + (2ttt - 3tt + 1)P2 + s(ttt - 2tt + t)P3 + (-2ttt + 3tt)P3 + s(ttt - tt)P4
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*/
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float s = (1 - tension) / 2;
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float b1 = s * ((-t3 + (2 * t2)) - t); // s(-t3 + 2 t2 - t)P1
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float b2 = s * (-t3 + t2) + (2 * t3 - 3 * t2 + 1); // s(-t3 + t2)P2 + (2 t3 - 3 t2 + 1)P2
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float b3 = s * (t3 - 2 * t2 + t) + (-2 * t3 + 3 * t2); // s(t3 - 2 t2 + t)P3 + (-2 t3 + 3 t2)P3
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float b4 = s * (t3 - t2); // s(t3 - t2)P4
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float x = (p0.x*b1 + p1.x*b2 + p2.x*b3 + p3.x*b4);
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float y = (p0.y*b1 + p1.y*b2 + p2.y*b3 + p3.y*b4);
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return PointF(x,y);
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}
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