added sprite entity trait

src/sprite_entity.c

@@ -0,0 +1,8 @@
+#include "sprite_entity.h"
+#include "sprite.h"
+
+void sprite_entity_draw(SpriteEntity self) {
+    Sprite* sprite = self.tc->get_sprite(self.data);
+    Transform* transform = self.transformable->get_transform(self.data);
+    sprite_draw(sprite, *transform);
+}

src/sprite_entity.h

@@ -0,0 +1,29 @@
+#ifndef _fencer_sprite_entity_h
+#define _fencer_sprite_entity_h
+
+#include "typeclass_helpers.h"
+#include "sprite.h"
+
+typedef struct {
+    Sprite* (*const get_sprite)(void*);
+} ISpriteEntity;
+
+typedef struct {
+    void* data;
+    ISpriteEntity const* tc;
+    ITransformable const* transformable;
+} SpriteEntity;
+
+extern void sprite_entity_draw(SpriteEntity self);
+
+#define impl_SpriteEntity_for(T, get_sprite_f)\
+static inline SpriteEntity T##_as_SpriteEntity(T* x) {\
+    TC_FN_TYPECHECK(Sprite*, get_sprite_f, T*);\
+    static ISpriteEntity const tc = {\
+        .get_sprite = (Sprite*(*const)(void*)) get_sprite_f,\
+    };\
+    Transformable t = T##_as_Transformable(x);\
+    return (SpriteEntity){.tc = &tc, .transformable = t.tc, .data = x};\
+}
+
+#endif // !_fencer_sprite_entity_h