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rubberduckycooly
GitHub Repository: rubberduckycooly/Sonic-1-2-2013-Decompilation
 Path: blob/main/RSDKv4/Math.cpp
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#include "RetroEngine.hpp"

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#include <math.h>

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#include <time.h>

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int sinM7LookupTable[0x200];

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int cosM7LookupTable[0x200];

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int sin512LookupTable[0x200];

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int cos512LookupTable[0x200];

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int sin256LookupTable[0x100];

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int cos256LookupTable[0x100];

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byte arcTan256LookupTable[0x100 * 0x100];

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void CalculateTrigAngles()

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{

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    srand(time(NULL));

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    for (int i = 0; i < 0x200; ++i) {

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        sinM7LookupTable[i] = (sin((i / 256.0) * M_PI) * 4096.0);

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        cosM7LookupTable[i] = (cos((i / 256.0) * M_PI) * 4096.0);

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    }

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    cosM7LookupTable[0x00]  = 0x1000;

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    cosM7LookupTable[0x80]  = 0;

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    cosM7LookupTable[0x100] = -0x1000;

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    cosM7LookupTable[0x180] = 0;

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    sinM7LookupTable[0x00]  = 0;

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    sinM7LookupTable[0x80]  = 0x1000;

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    sinM7LookupTable[0x100] = 0;

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    sinM7LookupTable[0x180] = -0x1000;

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    for (int i = 0; i < 0x200; ++i) {

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        sin512LookupTable[i] = (sinf((i / 256.0) * M_PI) * 512.0);

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        cos512LookupTable[i] = (cosf((i / 256.0) * M_PI) * 512.0);

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    }

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    cos512LookupTable[0x00]  = 0x200;

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    cos512LookupTable[0x80]  = 0;

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    cos512LookupTable[0x100] = -0x200;

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    cos512LookupTable[0x180] = 0;

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    sin512LookupTable[0x00]  = 0;

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    sin512LookupTable[0x80]  = 0x200;

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    sin512LookupTable[0x100] = 0;

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    sin512LookupTable[0x180] = -0x200;

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    for (int i = 0; i < 0x100; i++) {

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        sin256LookupTable[i] = (sin512LookupTable[i * 2] >> 1);

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        cos256LookupTable[i] = (cos512LookupTable[i * 2] >> 1);

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    }

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    for (int Y = 0; Y < 0x100; ++Y) {

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        byte *atan = (byte *)&arcTan256LookupTable[Y];

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        for (int X = 0; X < 0x100; ++X) {

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            float angle = atan2f(Y, X);

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            *atan       = (angle * 40.743664f);

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            atan += 0x100;

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        }

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    }

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}

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byte ArcTanLookup(int X, int Y)

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{

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    int x = 0;

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    int y = 0;

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    x = abs(X);

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    y = abs(Y);

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    if (x <= y) {

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        while (y > 0xFF) {

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            x >>= 4;

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            y >>= 4;

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        }

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    }

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    else {

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        while (x > 0xFF) {

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            x >>= 4;

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            y >>= 4;

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        }

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    }

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    if (X <= 0) {

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        if (Y <= 0)

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            return arcTan256LookupTable[(x << 8) + y] + -0x80;

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        else

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            return -0x80 - arcTan256LookupTable[(x << 8) + y];

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    }

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    else if (Y <= 0)

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        return -arcTan256LookupTable[(x << 8) + y];

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    else

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        return arcTan256LookupTable[(x << 8) + y];

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}

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