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comparison src/dmcurves.c @ 976:1b439304ff3c

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Add new module dmcurves, that will contain functions for spline generation etc and the LERP functions. Move LERP functions from dmlib.h to dmcurves.h.
author Matti Hamalainen <ccr@tnsp.org>
date Fri, 27 Feb 2015 16:16:59 +0200
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children fecf3967abee
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975:139b801f8d1c 976:1b439304ff3c
1 /*
2 * DMLib
3 * -- Curve and spline functions
4 * Programmed and designed by Matti 'ccr' Hamalainen
5 * (C) Copyright 2015 Tecnic Software productions (TNSP)
6 */
7 #include "dmcurves.h"
8
9
10 static inline const DMVector *dmSplineGetPoint(const DMVector *points, const int npoints, const int n)
11 {
12 return (n < 0) ? &points[0] : ((n < npoints) ? &points[n] : &points[npoints - 1]);
13 }
14
15
16 int dmBSplineGenerate(DMVector *dst, const int ndst, const DMVector *points, const int npoints, const int slod)
17 {
18 int cv, j;
19 DMVector *curr = dst;
20
21 for (cv = -3, j = 0; j != npoints + 1 && j < ndst; j++, cv++, curr++)
22 {
23 // for each section of curve, draw 'lod' number of divisions
24 int i;
25 for (i = 0; i != slod; i++)
26 {
27 // use the parametric time value 0.0 to 1.0 for this curve segment
28 const float t = (float) i / slod;
29
30 // inverse value of 't'
31 const float it = 1.0f - t;
32
33 // calculate blending functions for cubic bspline
34 const float t2 = t * t;
35 const float t3 = t2 * t;
36 const float b0 = it * it * it / 6.0f;
37 const float b1 = ( 3*t3 - 6*t2 + 4) / 6.0f;
38 const float b2 = (-3*t3 + 3*t2 + 3*t + 1) / 6.0f;
39 const float b3 = t3 / 6.0f;
40
41 // calculate the x,y and z of the curve point
42 curr->x = b0 * dmSplineGetPoint(points, npoints, cv + 0)->x +
43 b1 * dmSplineGetPoint(points, npoints, cv + 1)->x +
44 b2 * dmSplineGetPoint(points, npoints, cv + 2)->x +
45 b3 * dmSplineGetPoint(points, npoints, cv + 3)->x;
46
47 curr->y = b0 * dmSplineGetPoint(points, npoints, cv + 0)->y +
48 b1 * dmSplineGetPoint(points, npoints, cv + 1)->y +
49 b2 * dmSplineGetPoint(points, npoints, cv + 2)->y +
50 b3 * dmSplineGetPoint(points, npoints, cv + 3)->y;
51
52 curr->z = b0 * dmSplineGetPoint(points, npoints, cv + 0)->z +
53 b1 * dmSplineGetPoint(points, npoints, cv + 1)->z +
54 b2 * dmSplineGetPoint(points, npoints, cv + 2)->z +
55 b3 * dmSplineGetPoint(points, npoints, cv + 3)->z;
56 }
57 }
58
59 return (j == ndst) ? DMERR_OK : DMERR_BOUNDS;
60 }
61
62
63 int dmBSplineGenerateAlloc(DMVector **dst, int *ndst, const DMVector *points, const int npoints, const int slod)
64 {
65 if (ndst == NULL || dst == NULL)
66 return DMERR_NULLPTR;
67
68 if ((*ndst = dmBSplineGetNPoints(npoints, slod)) <= 0)
69 return DMERR_INVALID_DATA;
70
71 if ((*dst = dmCalloc(*ndst, sizeof(DMVector))) == NULL)
72 return DMERR_MALLOC;
73
74 return dmBSplineGenerate(*dst, *ndst, points, npoints, slod);
75 }