+#ifndef BLANK_WORLD_BLOCK_HPP_
+#define BLANK_WORLD_BLOCK_HPP_
+
+#include <glm/glm.hpp>
+
+
+namespace blank {
+
+/// single 1x1x1 cube
+struct Block {
+
+ using Type = unsigned short;
+ using Pos = glm::vec3;
+
+ enum Face {
+ FACE_UP,
+ FACE_DOWN,
+ FACE_RIGHT,
+ FACE_LEFT,
+ FACE_FRONT,
+ FACE_BACK,
+ FACE_COUNT,
+ };
+ enum Turn {
+ TURN_NONE,
+ TURN_LEFT,
+ TURN_AROUND,
+ TURN_RIGHT,
+ TURN_COUNT,
+ };
+
+ static constexpr int ORIENT_COUNT = FACE_COUNT * TURN_COUNT;
+
+ Type type;
+ unsigned char orient;
+
+ constexpr explicit Block(Type type = 0, Face face = FACE_UP, Turn turn = TURN_NONE) noexcept
+ : type(type), orient(face * TURN_COUNT + turn) { }
+
+ const glm::mat4 &Transform() const noexcept { return orient2transform[orient]; }
+
+ Face GetFace() const noexcept { return Face(orient / TURN_COUNT); }
+ void SetFace(Face face) noexcept { orient = face * TURN_COUNT + GetTurn(); }
+ Turn GetTurn() const noexcept { return Turn(orient % TURN_COUNT); }
+ void SetTurn(Turn turn) noexcept { orient = GetFace() * TURN_COUNT + turn; }
+
+ Face OrientedFace(Face f) const noexcept { return orient2face[orient][f]; }
+
+ static Face Opposite(Face f) noexcept {
+ return Face(f ^ 1);
+ }
+
+ static int Axis(Face f) noexcept {
+ switch (f) {
+ case FACE_UP:
+ case FACE_DOWN:
+ return 1;
+ default:
+ case FACE_RIGHT:
+ case FACE_LEFT:
+ return 0;
+ case FACE_FRONT:
+ case FACE_BACK:
+ return 2;
+ }
+ }
+
+ static glm::tvec3<int> FaceNormal(Face face) noexcept {
+ return face2normal[face];
+ }
+
+ static Face NormalFace(const glm::vec3 &norm) noexcept {
+ const glm::vec3 anorm(abs(norm));
+ if (anorm.x > anorm.y) {
+ if (anorm.x > anorm.z) {
+ return norm.x > 0.0f ? FACE_RIGHT : FACE_LEFT;
+ } else {
+ return norm.z > 0.0f ? FACE_FRONT : FACE_BACK;
+ }
+ } else {
+ if (anorm.y > anorm.z) {
+ return norm.y > 0.0f ? FACE_UP : FACE_DOWN;
+ } else {
+ return norm.z > 0.0f ? FACE_FRONT : FACE_BACK;
+ }
+ }
+ }
+
+ struct FaceSet {
+
+ explicit FaceSet(unsigned char v = 0)
+ : value(v) { }
+
+ bool IsSet(Face f) const {
+ return value & Mask(f);
+ }
+ void Set(Face f) {
+ value |= Mask(f);
+ }
+ void Unset(Face f) {
+ value |= ~Mask(f);
+ }
+
+ void Clear() {
+ value = 0;
+ }
+ void Fill() {
+ value = Mask(FACE_COUNT) - 1;
+ }
+
+ bool Empty() const {
+ return value == 0;
+ }
+ bool All() const {
+ return value == Mask(FACE_COUNT) - 1;
+ }
+
+ unsigned char Mask(Face f) const {
+ return 1 << f;
+ }
+
+ unsigned char value;
+
+ };
+
+private:
+ static const glm::tvec3<int> face2normal[6];
+ static const glm::mat4 orient2transform[ORIENT_COUNT];
+ static const Face orient2face[ORIENT_COUNT][FACE_COUNT];
+
+};
+
+}
+
+#endif