ft2-clone

Fasttracker 2 clone
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ft2_cubic_spline.c (1922B)

      1 // 4-point cubic Hermite spline (Catmull-Rom) interpolation LUT generator
      2 
      3 #include <stdint.h>
      4 #include <stdbool.h>
      5 #include <stdlib.h>
      6 #include "ft2_cubic_spline.h"
      7 #include "../ft2_video.h" // showErrorMsgBox()
      8 
      9 float *fCubicSplineLUT = NULL; // globalized
     10 
     11 bool setupCubicSplineTable(void)
     12 {
     13 	fCubicSplineLUT = (float *)malloc(CUBIC_SPLINE_WIDTH * CUBIC_SPLINE_PHASES * sizeof (float));
     14 	if (fCubicSplineLUT == NULL)
     15 	{
     16 		showErrorMsgBox("Not enough memory!");
     17 		return false;
     18 	}
     19 
     20 	float *fPtr = fCubicSplineLUT;
     21 	for (int32_t i = 0; i < CUBIC_SPLINE_PHASES; i++)
     22 	{
     23 		const double x1 = i * (1.0 / CUBIC_SPLINE_PHASES);
     24 		const double x2 = x1 * x1; // x^2
     25 		const double x3 = x2 * x1; // x^3
     26 
     27 		double t1 = (-0.5 * x3) + ( 1.0 * x2) + (-0.5 * x1);
     28 		double t2 = ( 1.5 * x3) + (-2.5 * x2) + 1.0;
     29 		double t3 = (-1.5 * x3) + ( 2.0 * x2) + ( 0.5 * x1);
     30 		double t4 = ( 0.5 * x3) + (-0.5 * x2);
     31 
     32 		*fPtr++ = (float)t1;
     33 		*fPtr++ = (float)t2;
     34 		*fPtr++ = (float)t3;
     35 		*fPtr++ = (float)t4;
     36 	}
     37 
     38 	/*
     39 	// 6-point Cubic Hermite (Catmull-Rom)
     40 	for (int32_t i = 0; i < CUBIC_SPLINE_PHASES; i++)
     41 	{
     42 		const double x1 = i * (1.0 / CUBIC_SPLINE_PHASES);
     43 		const double x2 = x1 * x1; // x^2
     44 		const double x3 = x2 * x1; // x^3
     45 
     46 		double t1 = ( (1.0/12.0) * x3) + (-(1.0/ 6.0) * x2) + ( (1.0/12.0) * x1);
     47 		double t2 = (-(7.0/12.0) * x3) + ( (5.0/ 4.0) * x2) + (-(2.0/ 3.0) * x1);
     48 		double t3 = ( (4.0/ 3.0) * x3) + (-(7.0/ 3.0) * x2) + 1.0;
     49 		double t4 = (-(4.0/ 3.0) * x3) + ( (5.0/ 3.0) * x2) + ( (2.0/ 3.0) * x1);
     50 		double t5 = ( (7.0/12.0) * x3) + (-(1.0/ 2.0) * x2) + (-(1.0/12.0) * x1);
     51 		double t6 = (-(1.0/12.0) * x3) + ( (1.0/12.0) * x2);
     52 
     53 		*fPtr++ = (float)t1;
     54 		*fPtr++ = (float)t2;
     55 		*fPtr++ = (float)t3;
     56 		*fPtr++ = (float)t4;
     57 		*fPtr++ = (float)t5;
     58 		*fPtr++ = (float)t6;
     59 	}
     60 	*/
     61 
     62 	return true;
     63 }
     64 
     65 void freeCubicSplineTable(void)
     66 {
     67 	if (fCubicSplineLUT != NULL)
     68 	{
     69 		free(fCubicSplineLUT);
     70 		fCubicSplineLUT = NULL;
     71 	}
     72 }