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Cherub

OpenGL OpenGL Game Programming

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Cherub    122
Hi, This question is for those who read this book: in the SimpEngine, described in the book, what do I need to do to separate the models from the terrain? Because if I don''t draw the terrain, the models aren''t drawn.... Thanks

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noisecrime    817
Hi Cherub,

Well it sounds like you''ll need to read the book again.
The reason why disabling the terrain, disables all other models is in there.

Its all to do with nodes and objects.
The concept of the simplengine is that every 3D object/model is dervived from the node/object base classes.

This allows for all objects to be linked together in a heirachy, the idea being to simplify the code for generating 3D worlds.

In this case the terrain is the root node, the player and enemy models are attached to it. So when calling Terrain draw function, its actually calling the object ondraw function. This function draws the model (terrain), then checks if there are any child nodes (players and enemies), if true it passes on the draw command to these children, who in turn will pass the command to thier children (e.g player - missile would be obvious one, but i''ve not got as far as checking if thats true).

If you want to disable the terrain from drawing then I would simply do

void CTerrain::OnDraw(CCamera *camera)
{
return;

// Rest of original function code
int z, x;
...

}

However if you do this all the models will be black!
This is because for some odd reason a number of important openGL states are set in the terrain on draw, which actually apply to the drawing off all models. So instead of adding the ''return'' at the start of the above function, place it after all the openGL states have been set.

This should achieve what you asked, however please note its hard to find the enemies without the terrain as you have no visual reference to allow you to search - you just have to move around randomly until you find one. You should still see your rockets firing though.

Finally if you make a debug build make sure you include the models folder and all the sound/bitmap files into the debug folder, otherwise the engine what be able to find them (although it doesn''t crash if it doesn''t find them - you just don''t see any models)

Hope this helps

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GalaxyQuest    122
Simple solution:
Create 2 root nodes:
One for the terrain as it''s own node.
One which is for all your objects.

An advanced solution might be:
Use a root node for terrain.
Use a quadtree structure, which has a root node in each quadtree section. Then, as you run through your quadtree for visible quadtree sections, you render the root object nodes as well.

Hope you get it.

- john

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