mat4 non-simd determinant

include/cglm-mat.h

@@ -124,4 +124,36 @@ glm_mat_transpose_self(mat4 m) {
 #endif
 }
 
+CGLM_INLINE
+float
+glm_mat4_det(mat4 mat) {
+  float a, b, c, d,
+        e, f, g, h,
+        i, j, k, l,
+        m, n, o, p
+  ;
+
+  float kp_ol, jp_nl, jo_nk,
+        jp_ml, io_mk, in_mj;
+
+  a = mat[0][0], b = mat[1][0], c = mat[2][0], d = mat[3][0],
+  e = mat[0][1], f = mat[1][1], g = mat[2][1], h = mat[3][1],
+  i = mat[0][2], j = mat[1][2], k = mat[2][2], l = mat[3][2],
+  m = mat[0][3], n = mat[1][3], o = mat[2][3], p = mat[3][3]
+  ;
+
+  kp_ol = k * p - o * l;
+  jp_nl = j * p - n * l;
+  jo_nk = j * o - n * k;
+  jp_ml = i * p - m * l;
+  io_mk = i * o - m * k;
+  in_mj = i * n - m * j;
+
+  return   a * (f * kp_ol - g * jp_nl + h * jo_nk)
+         - b * (e * kp_ol - g * jp_ml + h * io_mk)
+         + c * (e * jp_nl - f * jp_ml + h * in_mj)
+         - d * (e * jo_nk - f * io_mk + g * in_mj)
+  ;
+}
+
 #endif /* cglm_mat_h */