Create obj module for scene objects

include/obj.h

@@ -0,0 +1,35 @@
+#ifndef OBJ_H
+#define OBJ_H
+
+#include "ray.h"
+
+#define SPHERE(x, y, z, r) \
+	{ \
+		.intersect = intersect_sphere, \
+		.params = { \
+			.sphere = { .centre = { x, y, z }, .radius = r }, \
+		}, \
+	}
+
+typedef struct {
+	vec3_t point, normal;
+	double t;
+} hit_t;
+
+typedef struct {
+	vec3_t centre;
+	double radius;
+} sphere_params_t;
+
+typedef union {
+	sphere_params_t sphere;
+} obj_params_t;
+
+typedef struct {
+	bool (*intersect)(obj_params_t params, ray_t ray, hit_t *hit_out);
+	obj_params_t params;
+} obj_t;
+
+bool intersect_sphere(obj_params_t params, ray_t ray, hit_t *hit_out);
+
+#endif