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annotate src/dmcurves.c @ 984:0ba1ec9b8608

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Comment cleanups.
author Matti Hamalainen <ccr@tnsp.org>
date Fri, 27 Feb 2015 18:12:20 +0200
parents fecf3967abee
children 7df95aefb9c6
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1 /*
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2 * DMLib
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3 * -- Curve and spline functions
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4 * Programmed and designed by Matti 'ccr' Hamalainen
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5 * (C) Copyright 2015 Tecnic Software productions (TNSP)
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6 */
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7 #include "dmcurves.h"
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8
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9
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10 void dmLerpInit(DMLerpContext *ctx, DMFloat start, DMFloat end, DMFloat nsteps)
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11 {
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12 ctx->start = start;
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13 ctx->end = end;
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14 ctx->nsteps = nsteps;
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15 }
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16
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17
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18 DMFloat dmCatmullRom(const DMFloat t, const DMFloat p0, const DMFloat p1, const DMFloat p2, const DMFloat p3)
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19 {
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20 const DMFloat q = t * t;
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21 return (
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22 (2 * p1) +
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23 (-p0 + p2) * t +
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24 (2 * p0 - 5 * p1 + 4 * p2 - p3) * q +
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25 ( -p0 + 3 * p1 - 3 * p2 + p3) * q * t
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26 ) * 0.5f;
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27 }
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28
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29
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30 static inline const DMVector *dmSplineGetPoint(const DMVector *points, const int npoints, const int n)
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31 {
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32 return (n < 0) ? &points[0] : ((n < npoints) ? &points[n] : &points[npoints - 1]);
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33 }
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34
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35
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36 int dmBSplineGenerate(DMVector *dst, const int ndst, const DMVector *points, const int npoints, const int slod)
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37 {
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38 int cv, j;
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39 DMVector *curr = dst;
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40
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41 for (cv = -3, j = 0; j != npoints + 1 && j < ndst; j++, cv++, curr++)
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42 {
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43 // for each section of curve, draw 'lod' number of divisions
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44 int i;
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45 for (i = 0; i != slod; i++)
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46 {
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47 const float t = (float) i / slod;
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48 const float it = 1.0f - t;
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49
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50 // Calculate blending functions for cubic bspline
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51 const float t2 = t * t;
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52 const float t3 = t2 * t;
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53 const float b0 = it * it * it / 6.0f;
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54 const float b1 = ( 3*t3 - 6*t2 + 4) / 6.0f;
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55 const float b2 = (-3*t3 + 3*t2 + 3*t + 1) / 6.0f;
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56 const float b3 = t3 / 6.0f;
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57
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58 // Calculate coordinates of the curve point
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59 curr->x = b0 * dmSplineGetPoint(points, npoints, cv + 0)->x +
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60 b1 * dmSplineGetPoint(points, npoints, cv + 1)->x +
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61 b2 * dmSplineGetPoint(points, npoints, cv + 2)->x +
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62 b3 * dmSplineGetPoint(points, npoints, cv + 3)->x;
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63
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64 curr->y = b0 * dmSplineGetPoint(points, npoints, cv + 0)->y +
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65 b1 * dmSplineGetPoint(points, npoints, cv + 1)->y +
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66 b2 * dmSplineGetPoint(points, npoints, cv + 2)->y +
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67 b3 * dmSplineGetPoint(points, npoints, cv + 3)->y;
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68
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69 curr->z = b0 * dmSplineGetPoint(points, npoints, cv + 0)->z +
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70 b1 * dmSplineGetPoint(points, npoints, cv + 1)->z +
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71 b2 * dmSplineGetPoint(points, npoints, cv + 2)->z +
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72 b3 * dmSplineGetPoint(points, npoints, cv + 3)->z;
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73 }
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74 }
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75
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76 return (j == ndst) ? DMERR_OK : DMERR_BOUNDS;
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77 }
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78
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79
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80 int dmBSplineGenerateAlloc(DMVector **dst, int *ndst, const DMVector *points, const int npoints, const int slod)
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81 {
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82 if (ndst == NULL || dst == NULL)
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83 return DMERR_NULLPTR;
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84
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85 if ((*ndst = dmBSplineGetNPoints(npoints, slod)) <= 0)
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86 return DMERR_INVALID_DATA;
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87
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88 if ((*dst = dmCalloc(*ndst, sizeof(DMVector))) == NULL)
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89 return DMERR_MALLOC;
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90
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91 return dmBSplineGenerate(*dst, *ndst, points, npoints, slod);
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92 }