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Prt-2- .x File Format
Well its one thing to create a simple mesh....its just an array of x, y and z
coordinates....
Bones! Now thats an advanced topic we'd like to know more about....so
hold on to your hat where going in...
Bones....bones....bones....its not as tough as it sounds....you have a
body...which has an arm connected to it...you move the body, and the arm moves
with it....just keep that simple image in your head :) Bones in the .x
file format use the 'Frame' template
Now you'll need a lot of coffee and patience to grasp frame's...and bones...
as its a tricky one
Lets have a look at the formal definition:
Frame Aframe { // The frame name is
chosen for convenience.
FrameTransformMatrix {
...transform data...
}
[ Meshes ] and/or [ More frames]
}
Dear god...its looks horrible....if like me your looking at that definition
above crying...don't worry....stay carm...its not that bad....it will all become
clear in time :)
What we'll do is create 2 mesh's....two cubes and call them cubeA and cubeB....and
we'll make cubeA the body and cubeB a sort of arm..if you can picture that...
[NOTE]
We can embed our mesh's...our cubes in this case inside the 'Frame' or bones
if you want to call it them....or you can use references...where you declare
your Mesh earlier...then inside the Frame just use a reference like {CubeA} and
it refers to cubeA
Frame CubeFrame {
FrameTransformMatrix {
1.000000, 0.000000, 0.000000, 0.000000,
0.000000, 1.000000, 0.000000, 0.000000,
0.000000, 0.000000, 1.000000, 0.000000,
0.000000, 0.000000, 0.000000, 1.000000;;
}
{CubeA} // You
could have the mesh inline, but this
// uses an object reference instead.... problems problems problems....read
below
}
Now if you look above, you'll see that the FrameTranformMatrix is a identity
matrix...has 1's going across it...from top left to bottom
right.....anything applied to an identity matrix stays the same....so if we
multipy all of our Mesh CubeA values by an identity matrix it does nothing...but
on the other hand, we could put another matrix in there and have it scale or
move our CubeA...so keep that in mind.
[NOTE]
Now I've discovered that a number of .x file loaders
and viewers have a problem using the reference method...and always export
inline... So if possible always use the inline method....so if possible
put your Mesh's inline
For those who are keen on exploring and learning the various 3D file formats,
and excellent applications is 3D Exploration, which can be downloaded as
shareware, and allows you to view nearly all 3D file formats....a definite must
on your journey of adventure.
Nested Frames....this is where we use our Frame's as bones...and actually
achieve something new and exciting
Frame CubeFrameA { FrameTransformMatrix {
1.000000, 0.000000, 0.000000, 0.000000,
0.000000, 1.000000, 0.000000, 0.000000,
0.000000, 0.000000, 1.000000, 0.000000,
0.000000, 0.000000, 0.000000, 1.000000;;
}
Frame CubeFrameB{
FrameTransformMatrix {
1.000000, 0.000000, 0.000000, 0.000000,
0.000000, 1.000000, 0.000000, 0.000000,
0.000000, 0.000000, 1.000000, 0.000000,
0.000000, 0.000000, 0.000000, 1.000000;;
}
{CubeB}
}
{CubeA}
}
Now if we move CubeA, CubeB should follow...but if we only move CubeB then
CubeA won't follow.......notice that CubeFrameB is inside CubeFrameA...this
means its a child...
Its also tricky to picture in your head ...especially when your new to
matrix's and things...but the Matrix used on A has to be used on B as
well...think of it as a waterfall effect....the water trickles down the
stream...never goes up the stream ;)
I'll show you the whole thing...the whole piece of code....lets call it
bonecube.x
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xof
0303txt 0032
Header {
1;
0;
1;
}
// use comments to seperate out the parts-------------
Mesh
CubeA {
8; // 8 vertices
1.000000;1.000000;-1.000000;, // vertex 0
-1.000000;1.000000;-1.000000;, // vertex 1
-1.000000;1.000000;1.000000;, // etc...
1.000000;1.000000;1.000000;,
1.000000;-1.000000;-1.000000;,
-1.000000;-1.000000;-1.000000;,
-1.000000;-1.000000;1.000000;,
1.000000;-1.000000;1.000000;;
12; // 12 faces
3;0,1,2;, // face 0 has 3 vertices
3;0,2,3;, // etc...
3;0,4,5;,
3;0,5,1;,
3;1,5,6;,
3;1,6,2;,
3;2,6,7;,
3;2,7,3;,
3;3,7,4;,
3;3,4,0;,
3;4,7,6;,
3;4,6,5;;
}
//-----------------------------------------------------
Mesh
CubeB {
8;
// 8 vertices
1.000000;1.000000;-1.000000;, // vertex 0
-1.000000;1.000000;-1.000000;, // vertex 1
-1.000000;1.000000;1.000000;, // etc...
1.000000;1.000000;1.000000;,
1.000000;-1.000000;-1.000000;,
-1.000000;-1.000000;-1.000000;,
-1.000000;-1.000000;1.000000;,
1.000000;-1.000000;1.000000;;
12; // 12 faces
3;0,1,2;, // face 0 has 3 vertices
3;0,2,3;, // etc...
3;0,4,5;,
3;0,5,1;,
3;1,5,6;,
3;1,6,2;,
3;2,6,7;,
3;2,7,3;,
3;3,7,4;,
3;3,4,0;,
3;4,7,6;,
3;4,6,5;;
}
//Bone structure stuff is here------------------------
Frame
CubeFrameA {
FrameTransformMatrix {
1.000000,
0.000000, 0.000000, 0.000000,
0.000000,
1.000000, 0.000000, 0.000000,
0.000000,
0.000000, 1.000000, 0.000000,
0.000000,
0.000000, 0.000000, 1.000000;;
}
Frame
CubeFrameB{
FrameTransformMatrix {
1.000000, 0.000000, 0.000000, 0.000000,
0.000000, 1.000000, 0.000000, 0.000000,
0.000000, 0.000000, 1.000000, 0.000000,
0.000000, 0.000000, 0.000000, 1.000000;;
}
{CubeB}
}
{CubeA}
}
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Or if you use inline....so you put the mesh's inside the frame....it would
look like this:
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xof
0303txt 0032
Header {
1;
0;
1;
}
Frame
CubeFrameA {
FrameTransformMatrix {
1.000000,
0.000000, 0.000000, 0.000000,
0.000000,
1.000000, 0.000000, 0.000000,
0.000000,
0.000000, 1.000000, 0.000000,
0.000000,
0.000000, 0.000000, 1.000000;;
}
Frame
CubeFrameB{
FrameTransformMatrix {
1.000000, 0.000000, 0.000000, 0.000000,
0.000000, 1.000000, 0.000000, 0.000000,
0.000000, 0.000000, 1.000000, 0.000000,
0.000000, 0.000000, 0.000000, 1.000000;;
}
Mesh
CubeB {
8;
// 8 vertices
1.000000;1.000000;-1.000000;, // vertex 0
-1.000000;1.000000;-1.000000;, // vertex 1
-1.000000;1.000000;1.000000;, // etc...
1.000000;1.000000;1.000000;,
1.000000;-1.000000;-1.000000;,
-1.000000;-1.000000;-1.000000;,
-1.000000;-1.000000;1.000000;,
1.000000;-1.000000;1.000000;;
12; // 12 faces
3;0,1,2;, // face 0 has 3 vertices
3;0,2,3;, // etc...
3;0,4,5;,
3;0,5,1;,
3;1,5,6;,
3;1,6,2;,
3;2,6,7;,
3;2,7,3;,
3;3,7,4;,
3;3,4,0;,
3;4,7,6;,
3;4,6,5;;
}
}
Mesh
CubeA {
8; // 8 vertices
1.000000;1.000000;-1.000000;, // vertex 0
-1.000000;1.000000;-1.000000;, // vertex 1
-1.000000;1.000000;1.000000;, // etc...
1.000000;1.000000;1.000000;,
1.000000;-1.000000;-1.000000;,
-1.000000;-1.000000;-1.000000;,
-1.000000;-1.000000;1.000000;,
1.000000;-1.000000;1.000000;;
12; // 12 faces
3;0,1,2;, // face 0 has 3 vertices
3;0,2,3;, // etc...
3;0,4,5;,
3;0,5,1;,
3;1,5,6;,
3;1,6,2;,
3;2,6,7;,
3;2,7,3;,
3;3,7,4;,
3;3,4,0;,
3;4,7,6;,
3;4,6,5;;
}
} |
Well it may seem like a lot of work at first...but its truly not until you
start applying it to some small time projects that you'll drewl with amazment.....
for example you could have two parts .....lets say a tank...body and a gun...and
you could rotate the tank and the gun would rotate as well...but then you could
rotate the gun on its own......
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