added PhysicsEntity trait describing an object containing a rigidbody, shape and transform

src/physics_entity.h

@@ -0,0 +1,33 @@
+#ifndef _fencer_collidable_h
+#define _fencer_collidable_h
+
+#include "vmath.h"
+#include "typeclass_helpers.h"
+
+#include "rigidbody.h"
+#include "shape.h"
+
+typedef struct {
+    RigidBody* (*const get_rigidbody)(void* self);
+    Shape* (*const get_shape)(void* self);
+    Transformable (*const as_transformable)(void* self);
+} IPhysicsEntity;
+
+typedef struct {
+    void* self;
+    IPhysicsEntity const* tc;
+} PhysicsEntity;
+
+#define impl_PhysicsEntity_for(T, get_rigidbody_f, get_shape_f)\
+static inline PhysicsEntity T##_as_PhysicsEntity(T* x) {\
+    TC_FN_TYPECHECK(RigidBody*, get_rigidbody_f, T* e);\
+    TC_FN_TYPECHECK(Shape*, get_shape_f, T* e);\
+    static IPhysicsEntity const tc = {\
+        .get_rigidbody =     (RigidBody*(*const)(void*))  get_transform_f,\
+        .get_shape =         (Shape*(*const)(void*))      get_shape_f,\
+        .as_transformable =  T##_as_Transformable\
+    };\
+    return (PhysicsEntity){.tc = &interface, .self = x};\
+}
+
+#endif // !_fencer_collidable_h