new function to test

sweet_math.h

@@ -35,6 +35,7 @@
 #define SWEET_PI        3.141592653589793238462643
 #define SWEET_2PI       6.283185307179586476925286
 #define SWEET_GOLDEN_RATIO 1.618033988749894848204586
+#define SWEET_EPSILON   0.00000001
 
 /** RadianToDegree */
 /** @param Radian as float or double */
@@ -51,6 +52,9 @@
 #define sweet_math_approx_equals(a, b, epsilon) \
                 (a <= (b+epsilon) && a >= (b-epsilon))
 
+#define sweet_math_approx_zero(a, epsilon) \
+                (a <= (epsilon) && a >= (epsilon))
+
 /** Invsqrt */
 /** @param x argument of square root as float */
 /** @return 1 over square root as float */

sweet_matrix.c

@@ -149,6 +149,66 @@ sweet_matrix_identity4 (void)
     return m;
 }
 
+
+mat2 
+sweet_matrix_ortho_transform2 (vec2 u, vec2 v)
+{
+    mat2 m;
+    m.v[0] = u.x;
+    m.v[3] = v.x;
+
+    m.v[2] = u.y;
+    m.v[3] = v.y;
+
+    return m;
+}
+
+mat3 
+sweet_matrix_ortho_transform3 (vec3 u, vec3 v, vec3 w)
+{
+    mat3 m;
+    m.v[0] = u.x;
+    m.v[1] = v.x;
+    m.v[2] = w.x;
+
+    m.v[3] = u.y;
+    m.v[4] = v.y;
+    m.v[5] = w.y;
+
+    m.v[6] = u.z;
+    m.v[7] = v.z;
+    m.v[8] = w.z;
+
+    return m;
+}
+
+mat4 
+sweet_matrix_ortho_transform4 (vec4 u, vec4 v, vec4 w, vec4 t)
+{
+    mat4 m;
+    m.v[0] = u.x;
+    m.v[1] = v.y;
+    m.v[2] = w.z;
+    m.v[3] = t.w;
+
+    m.v[4] = u.x;
+    m.v[5] = v.y;
+    m.v[6] = w.z;
+    m.v[7] = t.w;
+
+    m.v[8]  = u.x;
+    m.v[9]  = v.y;
+    m.v[10] = w.z;
+    m.v[11] = t.w;
+
+    m.v[12] = u.x;
+    m.v[13] = v.y;
+    m.v[14] = w.z;
+    m.v[15] = t.w;
+
+    return m;
+}
+
 mat4
 sweet_matrix_perspective (double fovy, double aspect, double z_near, double z_far)
 {

sweet_matrix.h

@@ -35,6 +35,14 @@ mat2 sweet_matrix_identity2 (void);
 mat3 sweet_matrix_identity3 (void);
 mat4 sweet_matrix_identity4 (void);
 
+/** Basis */
+/** Vectors must be orthogonal */
+/** @param u, v, w, t as vector of the new basis */
+/** @return transform matrix to the new basis */
+mat2 sweet_matrix_ortho_basis2 (vec2 u, vec2 v);
+mat3 sweet_matrix_ortho_basis3 (vec3 u, vec3 v, vec3 w);
+mat4 sweet_matrix_ortho_basis4 (vec4 u, vec4 v, vec4 w, vec4 t);
+
 /** Frustum */
 /** @param Right as flaot */
 /** @param Left as float */