Use Vector4 for quaternion

include/core/Quaternion.h

@@ -4,11 +4,10 @@
 #include "core/Vector.h"
 
 typedef struct {
-    Vector3 xyz;
-    float w;
+    Vector4 v;
 } Quaternion;
 
-#define UNIT_QUATERNION ((Quaternion){{{0.0f, 0.0f, 0.0f}}, 1.0f})
+#define UNIT_QUATERNION ((Quaternion){{{0.0f, 0.0f, 0.0f, 1.0f}}})
 
 Quaternion* axisAngleQ(Quaternion* q, const Vector3* axis, float angle);
 Quaternion* lerpQ(Quaternion* q, const Quaternion* a, float f,

src/Quaternion.c

@@ -4,29 +4,27 @@
 #include "core/ToString.h"
 
 Quaternion* axisAngleQ(Quaternion* q, const Vector3* axis, float angle) {
-    q->xyz = *axis;
-    normalize(&q->xyz);
+    q->v.xyz = *axis;
+    normalize(&q->v.xyz);
     angle *= 0.5f;
-    q->w = cosf(angle);
-    mulSet(&q->xyz, sinf(angle));
+    q->v.w = cosf(angle);
+    mulSet(&q->v.xyz, sinf(angle));
     return q;
 }
 
 Quaternion* lerpQ(Quaternion* q, const Quaternion* a, float f,
                   const Quaternion* b) {
-    add(&q->xyz, mul(&a->xyz, 1.0f - f), mul(&b->xyz, f));
-    q->w = a->w * (1.0f - f) + b->w * f;
-    float iLength = 1.0f / sqrtf(squareLength(&q->xyz) + q->w * q->w);
-    mulSet(&q->xyz, iLength);
-    q->w *= iLength;
+    add(&q->v, mul(&a->v, 1.0f - f), mul(&b->v, f));
+    float iLength = 1.0f / length(&q->v);
+    mulSet(&q->v, iLength);
     return q;
 }
 
 Quaternion* mulSetQ(Quaternion* q, const Quaternion* o) {
-    float dot = dot(&q->xyz, &o->xyz);
-    add(&q->xyz, mul(&o->xyz, q->w),
-        add(mul(&q->xyz, o->w), cross(&q->xyz, &o->xyz)));
-    q->w = q->w * o->w - dot;
+    float dot = dot(&q->v.xyz, &o->v.xyz);
+    add(&q->v.xyz, mul(&o->v.xyz, q->v.w),
+        add(mul(&q->v.xyz, o->v.w), cross(&q->v.xyz, &o->v.xyz)));
+    q->v.w = q->v.w * o->v.w - dot;
     return q;
 }
 
@@ -38,14 +36,14 @@ Quaternion* mulQ(Quaternion* q, const Quaternion* a, const Quaternion* b) {
 
 Vector3* mulQV3(Vector3* r, const Quaternion* q, const Vector3* v) {
     Vector3 qv;
-    add(&qv, mul(v, q->w), cross(&q->xyz, v));
-    add(r, mul(&q->xyz, dot(&q->xyz, v)),
-        sub(mul(&qv, q->w), cross(&qv, &q->xyz)));
+    add(&qv, mul(v, q->v.w), cross(&q->v.xyz, v));
+    add(r, mul(&q->v.xyz, dot(&q->v.xyz, v)),
+        sub(mul(&qv, q->v.w), cross(&qv, &q->v.xyz)));
     return r;
 }
 
 size_t toStringQ(const Quaternion* q, char* buffer, size_t n) {
     return toString(buffer, n, "(%.3f i + %.3f j + %.3f k + %.3f)",
-                    (double)q->xyz.x, (double)q->xyz.y, (double)q->xyz.z,
-                    (double)q->w);
+                    (double)q->v.x, (double)q->v.y, (double)q->v.z,
+                    (double)q->v.w);
 }