The problems comes when Modules have to interact with other Modules. The solution seems to give each module a reference to the Engine in the constructor, but then, I have cyclic dependency.

The problem is not that modules need to interact with each other, it is how you have chosen to handle it.
Anything that should know about something else should know only about that something else. Handling off a bucket-load of miscellaneous pointers is just reshaping the same problem behind singletons and globals—you just want access to that global but you gain unwanted access to ten other systems.

Give out pointers when and where needed, and only give out the needed pointers.


L. Spiro

the most important thing is you must not depend on C++ books!

theres is not priciple like Object oriented..

It's just for convience that's all..

and it's come from MSI. not extremely depend on hardware situation...

I sujest conisder more coponent type hierachy..

every object stand basic concept of data...

in my own engine .. I use mesh . mesh is just mesh he doesn't have any parents. D3D device is also just device.

It's very depend on hardware and it's concept 3D engine designer cant abstract it's nature..

so ... we must admit we treat hardware and don't make any parent or abstract heirachy.

Object orient side is just by game programmer

3D engine programmer can use Object oriented method..Cause we dealing with hardware not human mind and processing

any help plz lets me know


I think good 3D engine is ... simple. easy to use. enough performance. that's all..

so you must divide concept as simple as.. make it as singlton and keep them as independent. don't save data already DirectX or OpenGL contain. minimize wrapping API(It's usless if don't you making real big comercial 3D engine)

and save your effort for making 3D engine as possible as

I hope it help you.

so you must divide concept as simple as.. make it as singlton

Before anyone jumps on that to turn this into yet another singleton thread, read these first, and then start a new discussion about it if there's something not already covered by the other 100 discussions on that pattern.

Assuming I'm fully understanding your issue, the "extern" keyword should help you out.

After the Engine class declaration I just do
[source lang="cpp"]extern Engine engine;[/source]
Now you can reference the engine, and all of the modules it contains from anywhere. I had pretty much the same issue you had when making my first engine in C++. extern made my life way easier.

The problem with [font=courier new,courier,monospace]class Engine[/font] or [font=courier new,courier,monospace]class Module[/font] (e.g. [font=courier new,courier,monospace]Renderer[/font] or [font=courier new,courier,monospace]Physics[/font] or [font=courier new,courier,monospace]Audio[/font]) is that those classes have waayyy too many responsibilities, so much so that you're not really using "OO" design any more.

When you've got such big classes, it does become very tempting to just make a single global instance that every other part of the code can connect to, because you've never broken it up enough in the first place in order to create sensible, small connections.

For example a scenegraph that contains nodes that needs to use the engine renderer? Where/How would you pass the render instance to the nodes?

"Scene graph" is a very vague term that refers to a lot of different designs, so I'll pretend we've got:
struct Node { std::vector<Node*> children; virtual void DoRendering(); void Traverse(); };
void Node::Traverse()
{
for( int i=0, end=children.size(); i!=end; ++i )
children->Traverse();
DoRendering();
}In this case, all you need to do is change [font=courier new,courier,monospace]DoRendering[/font] and [font=courier new,courier,monospace]Traverse[/font] so they take a single argument -- [font=courier new,courier,monospace]Renderer& renderer[/font].

However, as above, having a single massive class called [font=courier new,courier,monospace]Renderer[/font] might not be a good idea. I personally like to keep the "renderer" (whatever that is) and the "scene" seperate, so they don't need to communicate. Instead you ask the scene to give you a list of objects that need to be draw (and after that you don't need the scene at all). Then you can do whatever you need to with that list and a graphics device, in order to draw them.
struct Renderable { Mesh* mesh; std::vector<RenderState*> states; DrawCall draw; }
std::vector<Renderable*> renderables;
scene.Traverse( renderables ); // find all visible objects, put them into the above vector
std::sort( renderables.begin(), renderables.end(), someOptimisationCondition );//sort by depth/material/etc if required
for( int i=0, end=renderables.size(); i!=end; ++i )
{
Renderable& r = renderables;
device.Submit( r.draw, r.mesh, r.states );//issue the D3D/GL commands to draw this object
}

OO is a Tool that makes it easier to write and maintain complex systems

That's why it and ideas like SOLID and separation of concerns were invented
These guidelines weren't invented to impress teachers (who, in my experience, aren't often good programmers); they were invented so that large projects could be easily managed and reasoned about.

I have a class called Config that reads configurations from a LUA file. Almost all other module uses it, so now my solution is to pass it a reference in the constructor, witch seems right now.[/quote]That's a decent solution, but if you wanted to break it up more, so that there isn't this single "Config" entity that forges links between your entire code-base, you can break it up too, e.g.
/* foo.h */ class FooConfig { /* just foo stuff */ };
/* bar.h */ class BarConfig { /* just bar stuff */ };
/* config.h */ class FooConfig; class BarConfig;
class GlobalConfig { public: const FooConfig& GetFooConfig(); const BarConfig& GetBarConfig(); };
//cpp
#include all 3
int main()
{
GlobalConfig& cfg = ...;
Foo foo( cfg.GetFooConfig() );
Bar bar( cfg.GetBarConfig() );
}Now foo/bar don't have to have any connection between them at all, and instead at the next layer up in the code-base, the global-config composes them together into a useful whole.

Another matter of global access is a Log file that I have.[/quote]The "log file" example is always one that sparks a lot of discussion when it comes to globals/singletons/param-passing, and how best to deal with it...
Personally, I like to treat it specifically as an exception to the rule, because I don't see it so much as part of your application, but instead it's a part of the environment in which you're building your application. Things that form a part of your coding environment are ok to break the rules, because they're you're foundations and walls that need to be everywhere, holding up your code.
e.g. the connection to your IDE's debugger, or [font=courier new,courier,monospace]malloc[/font]/[font=courier new,courier,monospace]new[/font] or the call-stack, or the currently executing thread, are all 'environmental' features, like a debugging log. Every single bit of your code needs to run inside the environment created by these features.