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Added a Matrix Inverse Function (#14)

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This commit is contained in:
Thompson Lee 2016-07-31 07:20:36 -04:00 committed by fincs
parent ab534333b2
commit d7d5ba28a1
2 changed files with 131 additions and 0 deletions
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3
include/c3d/maths.h
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@ -2,6 +2,7 @@
#include "types.h"
#include <string.h>
#include <math.h>
#include <float.h>
// See http://tauday.com/tau-manifesto
//#define M_TAU 6.28318530717958647693
@ -62,6 +63,8 @@ static inline void Mtx_Copy(C3D_Mtx* out, const C3D_Mtx* in)
void Mtx_Identity(C3D_Mtx* out);
void Mtx_Multiply(C3D_Mtx* out, const C3D_Mtx* a, const C3D_Mtx* b);
bool Mtx_Inverse(C3D_Mtx* out);
void Mtx_Translate(C3D_Mtx* mtx, float x, float y, float z);
void Mtx_Scale(C3D_Mtx* mtx, float x, float y, float z);
void Mtx_RotateX(C3D_Mtx* mtx, float angle, bool bRightSide);

128
source/maths/mtx_inverse.c Normal file
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@ -0,0 +1,128 @@
#include <c3d/maths.h>
bool Mtx_Inverse(C3D_Mtx* out)
{
float inv[16], det;
int i;
inv[0] = out->m[5] * out->m[10] * out->m[15] -
out->m[5] * out->m[11] * out->m[14] -
out->m[9] * out->m[6] * out->m[15] +
out->m[9] * out->m[7] * out->m[14] +
out->m[13] * out->m[6] * out->m[11] -
out->m[13] * out->m[7] * out->m[10];
inv[4] = -out->m[4] * out->m[10] * out->m[15] +
out->m[4] * out->m[11] * out->m[14] +
out->m[8] * out->m[6] * out->m[15] -
out->m[8] * out->m[7] * out->m[14] -
out->m[12] * out->m[6] * out->m[11] +
out->m[12] * out->m[7] * out->m[10];
inv[8] = out->m[4] * out->m[9] * out->m[15] -
out->m[4] * out->m[11] * out->m[13] -
out->m[8] * out->m[5] * out->m[15] +
out->m[8] * out->m[7] * out->m[13] +
out->m[12] * out->m[5] * out->m[11] -
out->m[12] * out->m[7] * out->m[9];
inv[12] = -out->m[4] * out->m[9] * out->m[14] +
out->m[4] * out->m[10] * out->m[13] +
out->m[8] * out->m[5] * out->m[14] -
out->m[8] * out->m[6] * out->m[13] -
out->m[12] * out->m[5] * out->m[10] +
out->m[12] * out->m[6] * out->m[9];
det = out->m[0] * inv[0] + out->m[1] * inv[4] + out->m[2] * inv[8] + out->m[3] * inv[12];
if (fabsf(det) < FLT_EPSILON)
return false;
inv[1] = -out->m[1] * out->m[10] * out->m[15] +
out->m[1] * out->m[11] * out->m[14] +
out->m[9] * out->m[2] * out->m[15] -
out->m[9] * out->m[3] * out->m[14] -
out->m[13] * out->m[2] * out->m[11] +
out->m[13] * out->m[3] * out->m[10];
inv[5] = out->m[0] * out->m[10] * out->m[15] -
out->m[0] * out->m[11] * out->m[14] -
out->m[8] * out->m[2] * out->m[15] +
out->m[8] * out->m[3] * out->m[14] +
out->m[12] * out->m[2] * out->m[11] -
out->m[12] * out->m[3] * out->m[10];
inv[9] = -out->m[0] * out->m[9] * out->m[15] +
out->m[0] * out->m[11] * out->m[13] +
out->m[8] * out->m[1] * out->m[15] -
out->m[8] * out->m[3] * out->m[13] -
out->m[12] * out->m[1] * out->m[11] +
out->m[12] * out->m[3] * out->m[9];
inv[13] = out->m[0] * out->m[9] * out->m[14] -
out->m[0] * out->m[10] * out->m[13] -
out->m[8] * out->m[1] * out->m[14] +
out->m[8] * out->m[2] * out->m[13] +
out->m[12] * out->m[1] * out->m[10] -
out->m[12] * out->m[2] * out->m[9];
inv[2] = out->m[1] * out->m[6] * out->m[15] -
out->m[1] * out->m[7] * out->m[14] -
out->m[5] * out->m[2] * out->m[15] +
out->m[5] * out->m[3] * out->m[14] +
out->m[13] * out->m[2] * out->m[7] -
out->m[13] * out->m[3] * out->m[6];
inv[6] = -out->m[0] * out->m[6] * out->m[15] +
out->m[0] * out->m[7] * out->m[14] +
out->m[4] * out->m[2] * out->m[15] -
out->m[4] * out->m[3] * out->m[14] -
out->m[12] * out->m[2] * out->m[7] +
out->m[12] * out->m[3] * out->m[6];
inv[10] = out->m[0] * out->m[5] * out->m[15] -
out->m[0] * out->m[7] * out->m[13] -
out->m[4] * out->m[1] * out->m[15] +
out->m[4] * out->m[3] * out->m[13] +
out->m[12] * out->m[1] * out->m[7] -
out->m[12] * out->m[3] * out->m[5];
inv[14] = -out->m[0] * out->m[5] * out->m[14] +
out->m[0] * out->m[6] * out->m[13] +
out->m[4] * out->m[1] * out->m[14] -
out->m[4] * out->m[2] * out->m[13] -
out->m[12] * out->m[1] * out->m[6] +
out->m[12] * out->m[2] * out->m[5];
inv[3] = -out->m[1] * out->m[6] * out->m[11] +
out->m[1] * out->m[7] * out->m[10] +
out->m[5] * out->m[2] * out->m[11] -
out->m[5] * out->m[3] * out->m[10] -
out->m[9] * out->m[2] * out->m[7] +
out->m[9] * out->m[3] * out->m[6];
inv[7] = out->m[0] * out->m[6] * out->m[11] -
out->m[0] * out->m[7] * out->m[10] -
out->m[4] * out->m[2] * out->m[11] +
out->m[4] * out->m[3] * out->m[10] +
out->m[8] * out->m[2] * out->m[7] -
out->m[8] * out->m[3] * out->m[6];
inv[11] = -out->m[0] * out->m[5] * out->m[11] +
out->m[0] * out->m[7] * out->m[9] +
out->m[4] * out->m[1] * out->m[11] -
out->m[4] * out->m[3] * out->m[9] -
out->m[8] * out->m[1] * out->m[7] +
out->m[8] * out->m[3] * out->m[5];
inv[15] = out->m[0] * out->m[5] * out->m[10] -
out->m[0] * out->m[6] * out->m[9] -
out->m[4] * out->m[1] * out->m[10] +
out->m[4] * out->m[2] * out->m[9] +
out->m[8] * out->m[1] * out->m[6] -
out->m[8] * out->m[2] * out->m[5];
det = 1.0 / det;
for (i = 0; i < 16; i++)
out->m[i] = inv[i] * det;
return true;
}