From 4f0f81bb30f33b8e5f72008c2cf2ef438d5283e6 Mon Sep 17 00:00:00 2001
From: Cedric BAIL <cedric@osg.samsung.com>
Date: Wed, 24 Jun 2015 16:56:26 +0200
Subject: [PATCH] eina: add eina_matrix4_determinant.

---
 src/lib/eina/eina_matrix.c | 30 ++++++++++++++++++++++++++++++
 src/lib/eina/eina_matrix.h | 13 +++++++++++++
 2 files changed, 43 insertions(+)

diff --git a/src/lib/eina/eina_matrix.c b/src/lib/eina/eina_matrix.c
index 6c96893927..2e994df758 100644
--- a/src/lib/eina/eina_matrix.c
+++ b/src/lib/eina/eina_matrix.c
@@ -693,3 +693,33 @@ eina_matrix3_matrix4_to(Eina_Matrix4 *m4, const Eina_Matrix3 *m3)
    MATRIX_WZ(m4) = 0;
    MATRIX_WW(m4) = MATRIX_ZZ(m3);
 }
+
+EAPI double
+eina_matrix4_determinant(const Eina_Matrix4 *m)
+{
+   return
+       MATRIX_XW(m) * MATRIX_YZ(m) * MATRIX_ZY(m) * MATRIX_WX(m)
+     - MATRIX_XZ(m) * MATRIX_YW(m) * MATRIX_ZY(m) * MATRIX_WX(m)
+     - MATRIX_XW(m) * MATRIX_YY(m) * MATRIX_ZZ(m) * MATRIX_WX(m)
+     + MATRIX_XY(m) * MATRIX_YW(m) * MATRIX_ZZ(m) * MATRIX_WX(m)
+     + MATRIX_XZ(m) * MATRIX_YY(m) * MATRIX_ZW(m) * MATRIX_WX(m)
+     - MATRIX_XY(m) * MATRIX_YZ(m) * MATRIX_ZW(m) * MATRIX_WX(m)
+     - MATRIX_XW(m) * MATRIX_YZ(m) * MATRIX_ZX(m) * MATRIX_WY(m)
+     + MATRIX_XZ(m) * MATRIX_YW(m) * MATRIX_ZX(m) * MATRIX_WY(m)
+     + MATRIX_XW(m) * MATRIX_YX(m) * MATRIX_ZZ(m) * MATRIX_WY(m)
+     - MATRIX_XX(m) * MATRIX_YW(m) * MATRIX_ZZ(m) * MATRIX_WY(m)
+     - MATRIX_XZ(m) * MATRIX_YX(m) * MATRIX_ZW(m) * MATRIX_WY(m)
+     + MATRIX_XX(m) * MATRIX_YZ(m) * MATRIX_ZW(m) * MATRIX_WY(m)
+     + MATRIX_XW(m) * MATRIX_YY(m) * MATRIX_ZX(m) * MATRIX_WZ(m)
+     - MATRIX_XY(m) * MATRIX_YW(m) * MATRIX_ZX(m) * MATRIX_WZ(m)
+     - MATRIX_XW(m) * MATRIX_YX(m) * MATRIX_ZY(m) * MATRIX_WZ(m)
+     + MATRIX_XX(m) * MATRIX_YW(m) * MATRIX_ZY(m) * MATRIX_WZ(m)
+     + MATRIX_XY(m) * MATRIX_YX(m) * MATRIX_ZW(m) * MATRIX_WZ(m)
+     - MATRIX_XX(m) * MATRIX_YY(m) * MATRIX_ZW(m) * MATRIX_WZ(m)
+     - MATRIX_XZ(m) * MATRIX_YY(m) * MATRIX_ZX(m) * MATRIX_WW(m)
+     + MATRIX_XY(m) * MATRIX_YZ(m) * MATRIX_ZX(m) * MATRIX_WW(m)
+     + MATRIX_XZ(m) * MATRIX_YX(m) * MATRIX_ZY(m) * MATRIX_WW(m)
+     - MATRIX_XX(m) * MATRIX_YZ(m) * MATRIX_ZY(m) * MATRIX_WW(m)
+     - MATRIX_XY(m) * MATRIX_YX(m) * MATRIX_ZZ(m) * MATRIX_WW(m)
+     + MATRIX_XX(m) * MATRIX_YY(m) * MATRIX_ZZ(m) * MATRIX_WW(m);
+}
diff --git a/src/lib/eina/eina_matrix.h b/src/lib/eina/eina_matrix.h
index 83fff16540..8dc7014037 100644
--- a/src/lib/eina/eina_matrix.h
+++ b/src/lib/eina/eina_matrix.h
@@ -511,6 +511,19 @@ EAPI void eina_matrix4_values_get(const Eina_Matrix4 *m,
                                   double *zx, double *zy, double *zz, double *zw,
                                   double *wx, double *wy, double *wz, double *ww);
 
+/**
+ * @brief Return the determinant of the given matrix.
+ *
+ * @param m The matrix.
+ * @return The determinant.
+ *
+ * This function returns the determinant of the matrix @p m. No check
+ * is done on @p m.
+ *
+ * @since 1.15
+ */
+EAPI double eina_matrix4_determinant(const Eina_Matrix4 *m);
+
 /**
  * @brief Convert an Eina_Matrix4 into an Eina_Matrix3.
  *