I'm not sure what all the parts are called, please excuse my lack of knowledge on these items... I will refer to them by their colours on this image.
Back to the plan:
I have chosen the pivot points for the remaining objects (pink with white cross) at points where rotation will occur - usually at joints or bearings.
The new objects:
Red - an object fixed to the wheel
- no need for great detail here as it will be covered by a dark texture.
I will create a basic cube, resize it to 0.1,0.2,0.2, extrude the top
face by 0.3 and rotate the whole object in the X axis by -17 degrees (from
the plan)
To position it, drag the group containing the object onto the Wheels2
group and change the Y and Z positions to -0.35, 0.00. Then by constraining
the Z axis motion, drag with the mouse until it touches the piston rod
bearing.
Finally, to fix it into position, drag the new object out of the group
and into the Wheels2 group itself.
Orange - This rod behaves a bit like the driving rod from the piston.
To build this, I did a copy and paste of the wheel link rod onto the
scene. Then copied the rear bearing and pasted this onto the new Rod -
then set it's position to 0,0,0 and dragged the bearing into the same group
as the rod.
Selecting each object and running the Optimize operation removed the
textures I had applied to the original object (makes it easier to work
on)
I then scaled the rod to 1.43 long, and reduced it's width to 0.05.
I also scaled the bearing object size down slightly.
This moved the rod away from the pivot, so by selecting two diagonal
points on the end of the rod and by running the shift centre on selection
plugin, the position was restored.
Next I selected all the *edges* on the other end (away from the bearing)
and used the Y axis on the edit control (bottom right) to reduce the end
height by about 60% to give the rod some taper.
Now from the plan we can see this group needs to be a child object
of the wheel at Y = 0, Z = -0.1 (the group was also given a more meaningful
name)
Once again, by constraining Z axis movement, I use the mouse to position
the bearing against the Red object.
You should now be able to duplicate (using copy and paste) both the Red and Orange objects on the left side of the loco - you may need to use the Flip object operation on the orange rod so that it faces outward correctly. Also note the quartering affects the positions and that the rod on the Left must also be a child of the Wheels2 group on the right and not the Wheel group on the left (just to add to the confusion)
Now for the fun part - we can (and need to) animate all these parts before doing the rest.
Starting with the easiest...
Press Start and... Oh dear it missed!
This was where I realised the Engineer plugin builds objects slightly
above zero to stop the wheels sinking into the rails so my calculation
of the cylinder position was low - easlily adjusted by dragging the Cylinder
group up with the right mouse button so the piston is correctly centred.
Remember to press the Animate button again before you do anything else, or you will be left in animation mode and anything you do will apply to animation and not the original model. (the cause of many hiccups with models)
Yellow - The pivot for this object is attached to the main frame, so the object should be in a child group of the main group.
Starting with a cube scaled to 0.05, 0.30, 0.13 - I shift the pivot
point to the top face with the Shift centre plugin.
Select the top face again, this time switch to "edit using object coordinates"
on the top toolbar. As you move the mouse over the red bar on the edit
control, it should change to a plain cross.
Now drag slightly so the face rotates a few degrees.
Set the extrude operation to 0.15 with 0.0 bevel, and extrude the top
face.
Repeat the process after rotating the new top face a little more. Finally
I also rotated the bottom face of the object slightly for a more correct
shape.
The new object group was dragged into position just touching the end of the Orange object and the position (1.22, 1.48, 1.50) compared with the values obtained from the plan (not far out)
I copied and pasted this object back into the main group again and set the new group position to -1.22, 1.48 1.5 for the left side object (and renamed the new group to RevLeft)
Due to the quartering, this new object on the left needs to be rotated
slightly. This is done in a similar way to the rotation we did with the
top face, except this time with the whole object selected.
In Detail:

The way unoptimized levels of detail work in 3D canvas is that any object
not in the main group is removed over 700m - for this reason, I tend to
keep small static parts in a group (or two groups split by which ACE file
they use) - usually this division is above and below the footplate (I usually
call these groups UnderBits and TopBits)
A copy of this rod is placed in the same position on the Left side - and the object on the left was moved into the same "UnderBits" group.
Blue - This piece pivots on a point attached to the body, so it needs to be in a child group of the main object.
It is a cube resized to 0.03, 0.8, 0.055 with the bottom end extruded
by 0.02 and shrunk by 50% in the same way as the red object - to give a
rounded end. The pivot point is then shifted to the centre of the top face
(which I also made slightly wider as the plan shows the rod is not parallel)
The group is placed under the Main group, given some meaningful name
and positioned according to the plan.
Purple - This is a cube scaled to
about 0.03, 0.055, 0.6 and the centre shifted to the front end.
This objects animation is directly linked to the blue object so it
needs to be a child group of the blue objects group. This new child group
can be positioned exactly at 0, -0.79, 0
You should end up with an L shape like this:
Now, by using the "Edit using object coordinates" orientation mode,
rotate the Blue and Purple objects, by dragging the mouse over the axes
of the Edit control, in turn until they line up with the connection coming
out from the piston:
This is only a small change on the right side, but a bit more of a change on the left - it usually takes a few movements of each till the purple object lines up OK.
Once you have the Blue and Purple rods on the left side as well, we are ready to complete the animation manually.
On the Animation Toolbar, turn on Animation mode (press the Animate button)
Now get a close look at the yellow object on the right side:
Don't worry too much about small errors in positions with these animations, they all get smoothed out when running.
Now cull those hidden faces again! (and re-optimize each object you do this to) - Using the count triangles plugin, I can see I'm still only at 2388 polygons.
At this point I'll start mentioning some bits about texturing - I have
updated the texture slightly to fit in the bearing ends and the colour
and lining for the Cylinder - note these do not need to be the same shape
as the plan, you can stretch textures, though be careful if you are adding
noise (later lesson) as this will stretch too.
All the currently un textured parts will be at least grey so the first thing I do is select a small area of texture (in this case a few pixels square from the centre of the con rod) and use the fill tool on everything.
When applying a texture to a whole object you can preview the way in
which the texture will be applied by switching to the "Highlight selection
showing operation direction" mode - it gets a bit confusing so I tend to
switch the mode off after finding the correct orientation
This basically shows how a square texture will be applied according to which of the 5 orientation modes is selected - if you switch orientation mode, the square texture pattern changes accordingly.
The Default orientation mode "snaps" to right angles.
Screen orientation basically overlays the square on the screen
viewport - you just adjust the model to the viewport.
World orientation is always fixed.
Object orientation is similar to world, but is affected by object
rotation.
Face orientation - not quite sure about this one yet.
The bearing objects are still isolated so I can use the fill tool to
give them the circular pattern on the front face (using default orientation)
Filling is actually good for efficiency as a point on the model need
only be represented once - if you paint each face separately, a single
point needs to be represented by more than one "vertex" - which includes
the texture coordinate.
I want a similar (but more central circle) for the piston object - for
this I adjust the texture cropping and just select the single square face
in the middle and press the "Apply Material" Object Operation button on
the left (don't use the paintbrush button on the right - this tends to
muck up the object normals giving odd lighting effects)
For the tapered rods, I crop the texture, select "Edit using face orientation" (seems to produce the mapping to what I want), then select the outer face and use the "Apply Material" Operation on each one.
This then needs a slight adjustment on each to taper the texture - select
the face you want to adjust, then press the
UV Edit operation (the
one with the red grid on it) - a window pops up and you can use this to
zoom in and adjust texture points. By squaring up the mapping, the texture
will taper with the face.
For the cylinder texture, I selected the faces I wanted to cover, but
could not find an exact orientation match.
I applied the material with the default mode, then selected the "Operation Adjust Tool" (two round arrows) on the right toolbar and selected the cylinder object. Then by dragging on the red axis of the edit control (as if you are rotating an object) the texture was aligned correctly.
I added a few other slight texture updates and exported to MSTS...
NOW BEFORE YOU RUN IT IN THE SIM!!!
We are now using 16 frame animation so you must edit the S file and change the line (near the end of the file):
or your wheels will rotate at half speed.animation ( 16 30to
animation ( 16 60
Poetry in motion....
| Posted: 08 Jan 2003 22:51 Post subject: | |
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| Decapod,
If you, or anyone else, want to know about locomotive valve gears go to:- look for the Windows version.
regards
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