Map File Format
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I just started experimented with tile based games and I am writing a level editor.
Right now I am just using a 2d array of integers to store the id of all the tiles.
That works great, but how do I store entitites like teleports to other maps (doors), enemies and other NPCs ?
There are two schools of thought on this:
1) Make the entities tiles themselves. Upside: easiest to implement. Downside: moving entities have issues as far as what is underneath them...nothing.
For example, teleporters. If you are using int''s (32-bits), use the low 16 bits for your item/tile ID, and use the high 16 bits for an X/Y destination.
2) Have a seperate data structure for entities. Upside: more flexible, can extend easily. Downside: added layer of complexity.
For example, create a linked list of entities. Every time you or another entity moves, check the positions of all of the entities in the linked list.
How would I store them? Personal preference: store the map in one file, entities in another, or use a PAK-style file format and combine them that way. I come from a testing background, and I''ve seen too many instances where when too much stuff was combined into a single file, and a change to one area had wide-ranging effects on others.
RomSteady - Able to leap off tall buildings in a single bound
1) Make the entities tiles themselves. Upside: easiest to implement. Downside: moving entities have issues as far as what is underneath them...nothing.
For example, teleporters. If you are using int''s (32-bits), use the low 16 bits for your item/tile ID, and use the high 16 bits for an X/Y destination.
2) Have a seperate data structure for entities. Upside: more flexible, can extend easily. Downside: added layer of complexity.
For example, create a linked list of entities. Every time you or another entity moves, check the positions of all of the entities in the linked list.
How would I store them? Personal preference: store the map in one file, entities in another, or use a PAK-style file format and combine them that way. I come from a testing background, and I''ve seen too many instances where when too much stuff was combined into a single file, and a change to one area had wide-ranging effects on others.
RomSteady - Able to leap off tall buildings in a single bound
You could have an identifier (byte) for each special type you want to safe
Then when you want to write the objects, just use something like
And when you want to read them:
I have NO idea if it works and it''s probably not a very good way to save objects.. At least it looks pretty ugly. But I just felt the urge to write something :D
enum Specials { ID_TELEPORT, ID_ENEMY, ID_NPC, NO_MORE_SPECIALS };class Teleport { //... char getType() const { return ID_TELEPORT; }}class Npc { //... char getType() const { return ID_NPC; }} Then when you want to write the objects, just use something like
template<typename T>void writeObject(const T& object) { writeByte(object.getType()); writeInt(sizeof(object)); //writes all bytes from the object, one by one writeAll(&object, sizeof(object));}//somewhere else:{ Teleport teleport1; Npc myNpc; writeObject(teleport1); writeObject(myNpc); //use a loop to write all the stuff from the editor :D writeByte(NO_MORE_SPECIALS);} And when you want to read them:
while(true) { char identifier = readByte(); if (identifier == NO_MORE_SPECIALS) break; int sizeOfNewObject = readInt(); void* memoryForNewObject = reinterpret_cast<void*>(new char[sizeOfNewObject]); //reads sizeOfNewObject amount of bytes one by one and stores them to memoryForNewObject readAll(memoryForNewObject, sizeOfNewObject); switch (identifier) { case ID_TELEPORT: addTeleport(reinterpret_cast<Teleport*>(memoryForNewObject)); break; case ID_NPC: addNPC(reinterpret_cast<Npc*>(memoryForNewObject)); break; }} I have NO idea if it works and it''s probably not a very good way to save objects.. At least it looks pretty ugly. But I just felt the urge to write something :D
Oh yah, I forgot to mention... If you want a safer method which needs more writing, try this:
And to read
That way you need to write writeMe() and readMe() functions for all object types.. But if your objects contain pointers, then you must do it this way.
class Teleport { //... void writeMe() { writeByte(ID_TELEPORT); writeInt(x); //x, y coordinates and so on writeInt(y); } void readMe() { readInt(x); readInt(y); }}//somewhere else{ teleport.writeMe(); writeByte(NO_MORE_SPECIALS);} And to read
while(true) { char identifier = readByte(); if (identifier == NO_MORE_SPECIALS) break; switch (identifier) { case ID_TELEPORT: Teleport* teleport = new Teleport(); teleport->readMe(); addTeleport(teleport); break; case ID_NPC: Npc* npc = new Npc(); npc->readMe(); addNpc(npc); break; }} That way you need to write writeMe() and readMe() functions for all object types.. But if your objects contain pointers, then you must do it this way.
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