Australian MSTS @ Steam4me Tutorials A Coach made with Gmax - Page 13

A Coach made with Gmax - Page 13

by Richard Osborne

BUILDING HINTS & TIPS

Now that you've built some stock using the most simple techniques it's time to find a few more goodies in the Gmax treasure chest. You'll find now that the Help File isn't quite as impenetrable as it was. Like all good CAD programs Gmax can use snaps. If you wish to make a point exactly meet another the program will find the target point. Obviously you have to guide it & constrain it, I always set the range to be quite near & work in close. If you set the range too high it'll join to the wrong point & be a pain to correct (remember to set your undo level high). Right-click on the snap icon to see the options screens. Span to 'Vertex' & 'Endpoint' are going to be the most useful; snap to 'Pivot' will be useful for animating loco valvegear. 'Options' lets you set colour, size & strength of the snap. Snap can be turned on & off with Keyboard S.

Grab the point you wish to move, the 'Snap' symbol will appear. For some reason the cruciform 'Move' symbol hasn't shown in these screenies.

Drag the point nearer to the target; the 'Snap' symbol will find the target. Finger off the button & the point will snap across - magic & no measuring. We could have used this moving all those points on the coach ends.

It's very useful to be able to change the viewport configuration. If you put the mouse over the viewport title & right-click you'll have a menu. Most useful are 'Views' to change the view type & 'Configure'. The first screen echoes the changes you can make with F2, F3 & F4; click 'Layout' to change the variety of windows. Sometimes you'll only want 2 or 3.

As with other programs you can drag the borders to give more options; 1 large window, 3 small on the left.... You can also have the same view in more than 1 window - 4 perspective views, solid, wireframe, solid with wireframe showing....

It's so, so easy to get carried away with the detail parts. Handrails, vents & buffers can have more polygons than the coach itself.

It's easiest here to start with a cylinder in top view; remember .025m is 1in. Grip an imaginary rail & measure it. There's always a bit of license in any form of modelling - too big it looks silly, too small & there's no point having it.

In point mode pull & push cross sections into approximate position. Both ends will turn 90 degrees in side view.

Go in close, change to 'Rotate' mode & twist each group to halve the angle. Rotate the ends into the body. When you're happy with it clone, mirror & join. 220 polygons!!

I mentioned lit interiors early in the tutorial & forgot to come back to them. I'm not entirely convinced by them, at night they're fine giving the impression that there might be someone in the coaches. By day the interiors are still lit - they should be darker relative to the ambient light. The effect can be seen with the default LNER coaches. Try it; it can always be changed later if you don't like it.

The list of lighting palette conditions work in Gmax. As before the texture state must have an unique name. That 'Texture Level' window alters the opacity of the texture. It's not of much value to us unless we're making ghost trains. You could use it during modelling - you'd see through the sides at the interior. Turn it back up during exporting to MSTS.

One of the best features of TSM is the ability to store parts; it keeps them neatly tucked away for reuse for other projects or if you make an error. Sadly Gmax doesn't do this, it tells you you can save an individual part as 'Save Selected' but look at t hat part in 'Explorer' - it's huge!! Gmax saves that part as a scene, all the background info, colours, preferences etc. are included. There is a way to store parts though.. Under the 'File' menu you'll see 'Merge'. Try this on a blank screen. Press 'Merge', a screen appears. It'll open at the path you've specified for 'Scenes'. All fairly normal highlight & pick.

Now a 700 boiler is the same as a T9 boiler, nearly the same as an L12 boiler. A few stretches and pulls makes all the difference.

BIG WARNING!!!! Merged parts will have texture information with them. Gmax will alias textures used in a project back to their original directory. You MUST have texture & model files in the same directory. If not your .s file will be full of alias information. Your exported model might work on your computer but wouldn't have a hope of working on mine.

Re-texture parts to the file in your project directory. Look at the model in Shape View & press 'Edit', 'Textures'. SView will list the texture files used - one of its most useful features. Gmax will hang on to textures like a limpet!! Even one polygon unchanged will call for the original texture file. If you find files you didn't expect untick the others to isolate the parts with original textures.

The Material Editor will still be full of useless information. Make sure your project is saved. Open a new screen & merge your project to it - all the parts you still need. Rename the project; I'll jump from 700_10 to 30339_1, something significantly different.

Going back to our saving parts problem it's evident you could have a scene just for parts, though there's not as much need for it as you'd suppose. Merging from other projects is quick & foolproof. One thing though - give your parts sensible names. I once downloaded a sample aircraft model - excellent except for the naming of parts, it had box.1.1.1.1.1.1.1.1.1.1.1.1.1.1.1.1. as well as box.1.1.1.1.1.1.1.1.1.1.1.1.1.1.1. - not very easy to tell apart!

Now that we've added so many parts & polygons it's time to think about losing them. LoD is a way of modelling so that you have literally 3 models, 1 which shows close-to, 1 for mid-distance & 1 for the distance. You can have more than 3, some of the KUJU models have 6 levels. Look at the GP38 in SView, you can see the differences of LoD. I think that particular model is overdone, there's not that much improvement to frame rate if you have a decent graphics card. I've a sneaky feeling that some designers get carried away when the LoD manager is open.

The principle is simple enough, start with the most detailed model & remove polygons for more distant views. Gmax insists that you remove polygons from parts; you can't delete parts! Even if the part has only a couple of polygons it must be there.

There's no rule about distances, I'd suggest looking at the model in SView & changing the viewing distance. When a part becomes too small to see it needn't be there. Viewing MSTS in 2 or 3 view seems to show trains at about 150m. I'll set distances here at 100m, 250m & 1500m. TSM sets the default at 2000m. I have my version of MSTS set to 1500m visibility, it's rare in Britain to have much better.

Messing about with the LoD manager is an open invitation for Gmax to crash. Start with a freshly saved file & turn autosave off. You could join smaller parts together, bulkheads together, bufferstocks to bufferheads, handrails to steps etc. More polygons per part.

The first level is simple enough - just set the distance to 100m. As before the alpha sorting must be specified. Now press the large + again & set the distance to the next level, 250m. Take a part which you know will not be seen, the buffers for example. Highlight buffers on the Lod Manager list, 'Polygon' mode then lassoe a bunch of polygons.

Press 'Delete' & OK to 'Delete Vertices'.

At this 250m level I'd also trim the couplings, axleboxes, handrails, seats etc.

Add another Lod level at 1500m, trim more of the buffers - I've left only the heads at the guard's end, wheelrims, vents, anything else which might be trimmed. I'm reluctant to omit things like bulkheads, you can see them at this distance. Corridor connections should be kept or you'll see a gap between coaches. You could alter polygons, the corridor connection could be pulled up to height. Don't try to re-map the polygon!!

When you export this time you'll see the progress bar several times as each level is written. This might hurt but you must still go into 'Operations' & 'Remove Lod information from MAX scene'. Gmax will crash if you don't. Although it would be good to have a practice run or two normally LoD is going to be your last operation, don't get involved until you're ready for final export.


 

End of page 13
20 Oct 2004