Woooowwwwww!!, Ron .. too big list of questions .... , I hope doug will answer all ..... even i want to know the answers of these questions... and i think the near plane means.. than for a camera there is a area of the view which is a area covered by two planes.. one the near plane and the other is the far plane... both of these combine and say what is the viewing area of the camera..... and near plane is the nearest place a camera can see anything before this will not be seen by the camera... Doug i think i'm correct.. please rectify me if i'm not.....

and doug and ron , if u guys don't mind.. can i also add one more question to Ron's list....

When we say the reasons for the transparent polygons is because of the reasons what doug has given... fine... but doug tell me I have a block or a map entity in my level .. which i go near i don't see what is there beyond it.. but i can just simply walk through that object..... why is it ??? where is the collision detected ???
Please help me.... there is a major problem... I have a small wall like blocks kept at the edges of clif like mountain so that my player don't fall of the mountain ... but the problem of this walk through blocks.. my player can happly walk through it and fall of the clif... don't u think it looks bad !!! Please help me.....

With regards,
Sac