50 lines
1.5 KiB
C
50 lines
1.5 KiB
C
/******************************************************************************
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Plush Version 1.2
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spline.c
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n-th Dimensional Spline Interpolator
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Copyright (c) 1996-2000, Justin Frankel
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******************************************************************************/
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#include "plush.h"
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void plSplineGetPoint(pl_Spline *s, pl_Float frame, pl_Float *out) {
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pl_sInt32 i, i_1, i0, i1, i2;
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pl_Float time1,time2,time3;
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pl_Float t1,t2,t3,t4,u1,u2,u3,u4,v1,v2,v3;
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pl_Float a,b,c,d;
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pl_Float *keys = s->keys;
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a = (1-s->tens)*(1+s->cont)*(1+s->bias);
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b = (1-s->tens)*(1-s->cont)*(1-s->bias);
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c = (1-s->tens)*(1-s->cont)*(1+s->bias);
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d = (1-s->tens)*(1+s->cont)*(1-s->bias);
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v1 = t1 = -a / 2.0; u1 = a;
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u2 = (-6-2*a+2*b+c)/2.0; v2 = (a-b)/2.0; t2 = (4+a-b-c) / 2.0;
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t3 = (-4+b+c-d) / 2.0;
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u3 = (6-2*b-c+d)/2.0;
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v3 = b/2.0;
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t4 = d/2.0; u4 = -t4;
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i0 = (pl_uInt) frame;
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i_1 = i0 - 1;
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while (i_1 < 0) i_1 += s->numKeys;
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i1 = i0 + 1;
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while (i1 >= s->numKeys) i1 -= s->numKeys;
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i2 = i0 + 2;
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while (i2 >= s->numKeys) i2 -= s->numKeys;
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time1 = frame - (pl_Float) ((pl_uInt) frame);
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time2 = time1*time1;
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time3 = time2*time1;
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i0 *= s->keyWidth;
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i1 *= s->keyWidth;
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i2 *= s->keyWidth;
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i_1 *= s->keyWidth;
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for (i = 0; i < s->keyWidth; i ++) {
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a = t1*keys[i+i_1]+t2*keys[i+i0]+t3*keys[i+i1]+t4*keys[i+i2];
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b = u1*keys[i+i_1]+u2*keys[i+i0]+u3*keys[i+i1]+u4*keys[i+i2];
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c = v1*keys[i+i_1]+v2*keys[i+i0]+v3*keys[i+i1];
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*out++ = a*time3 + b*time2 + c*time1 + keys[i+i0];
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}
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}
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