Vector indexing function.

Could use a union to give direct array access. May implement later.

diff --git a/math3d.h b/math3d.h
index 465f7f5..0671d7b 100644 (file)
--- a/math3d.h
+++ b/math3d.h
@@ -235,7 +235,7 @@ static inline struct vec vsub2(struct vec a, struct vec b, struct vec c) {
 }
 
 //
-// conversion to/from raw float and double arrays.
+// conversion to/from raw float and double arrays; array-like access.
 //
 
 // load a vector from a double array.
@@ -254,6 +254,10 @@ static inline struct vec vloadf(float const *f) {
 static inline void vstoref(struct vec v, float *f) {
        f[0] = v.x; f[1] = v.y; f[2] = v.z;
 }
+// index a vector like a 3-element array.
+static inline float vindex(struct vec v, int i) {
+       return ((float const *)&v.x)[i];
+}
 
 
 // ---------------------------- 3x3 matrices ------------------------------

diff --git a/test.c b/test.c
index 1565737..626587a 100644 (file)
--- a/test.c
+++ b/test.c
@@ -59,6 +59,16 @@ do { \
 // tests - when adding new tests, make sure to add to test_fns array
 //
 
+void test_vec_basic()
+{
+       struct vec v = mkvec(1.0f, 2.0f, 3.0f);
+       assert(vindex(v, 0) == 1.0f);
+       assert(vindex(v, 1) == 2.0f);
+       assert(vindex(v, 2) == 3.0f);
+
+       printf("%s passed\n", __func__);
+}
+
 void test_mat_axisangle()
 {
        srand(0); // deterministic
@@ -147,6 +157,7 @@ void test_qvectovec()
 // micro test framework
 typedef void (*voidvoid_fn)(void);
 voidvoid_fn test_fns[] = {
+       test_vec_basic,
        test_mat_axisangle,
        test_quat_rpy_conversions,
        test_quat_mat_conversions,