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LEARNING VRHOTWIRE’S
SCRIPTING LANGUAGE:VRNACULAR


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version 1.0












SCRIPTING WITH VRNACULAR
 
 

          In the beginning there is the panorama.

You finally figure out how to make a nice one, and put it on the web.

You make a few, perhaps many. Then you want to add more features
to your movie. Your client has some ideas...

But you're a photographer, not a programmer!
At first you're happy using vrhotwires 'tools' menu items to generate  scripts for you.
But code that's generated automatically has limitations.

You want a more custom look and feel to your movie.
Handcrafted in every detail...

After a while you start looking at those auto-generated scripts made by the tools and trying to understand them. (by going to 'script window' under views (command r)) You notice that if you set the preference to not
write out scripts using macros you get a lot more detail!


and then you start trying to change the odd thing...

you learn how the 'script to movie' buton works...

Now you want control over this scripting thing!

That brings you to learning VRNacular.

There's another document in this folder that acts like a dictionary of VRNacular,
here we walk you through the scripting process...

Hope you find it easy!
 
 
A First Script

The Menus 








A first script 
 
 
Open vrhotwires
 
drag your vr movie  onto the white window to open it.
 
Press 'command R' or choose 'script' from under the views window.
 
Copy and paste this script into that window:.

Under the Node Number: 1
 

On Idle
            SetPanAngle 3 delta
end

 
 
  Now press the 'script to movie' button. 

erty  
Your movie should be autopanning. (if it isn't make sure it has a qtvr track. If not, update it to qtvr 2.0 using deliVRator from vrtools.com)

Now, do you know how to speed it up? Make it spin faster?

Make this the script: (change the 3 to a 7)
 

On Idle
            SetPanAngle 7 delta
end

Press "Script to movie" to see the increase in speed of panning.



 
If you press the "Movie To Script" button you'll get...

On Idle
            QTVRSetPanAngle 7 delta
end

This is because the real call is QTVRSetPanAngle but a few commands can be typed in using abbreviated names... like SetPanAngle SetTiltAngle SetVar etc.


If the middle line was shortened to read:
SetPanAngle 7
the movie would go to 7 degrees and stay there.

But we've said 'delta' which means
'add 7 to the existing pan angle'.

By increasing the delta we make the pan faster.
and how do I make it go the other way?

On Idle
            SetPanAngle -3 delta
end



Hey, it doesn't work right. The movie stops panning when it gets to zero!!
 

That's because qtvr doesn't want negative numbers. You need to make it wrap.

Try this instead:

On Idle
            SetPanAngle neg3 delta wrap min=0 max=360
end
 

Hmm, min and max huh? so does that mean I can make it just go half way and then start again from zero?

On Idle
            SetPanAngle neg3 delta wrap min=0 max=180
end

cool....


Now what do all these popup menus do?

Now what if I just want to look at the script of one hotspot or sprite? 




THE MENUS

The menus in vrhotwires make scripting easy. Or at least they take most of 
the type-ing out of the process. 

Most of the time just working left to right will get you a script. 



fghj

if you chose the On Mousedown Hotspot
from the first and the menus above you'll get

On MouseDown Hotspot ?

             QTVRSetPanAngle ?
end


wherever there's a ? you have to fill in a value.

what we're looking for is a complete script that looks like

On MouseDown Hotspot 3

             QTVRSetPanAngle 99
end

You can use the third menu for operands

perhaps you want to say

QTVRSetPanAngle theTiltAngle

you could choose your operand from here.

wert



DESIGN GOALS:



 To write a real script we'll have to do some design

Let's start by writing down what we want our movie to do:
 
 
 "I want my movie to pan when I press a button at the bottom"

"I want my movie to play the sound of the dog barking three times, then pan over to the bad guy, and play the linear transition of the bad guy doing a flip"

"I have a pano  of a park, and I want a girl riding a  bike to ride through a couple times every minute"
 

With that as our basis, we can derive a script that will do what we're trying to achieve.

Eventually scripting languages might evolve that allow you to use descriptions like these... for now we' ll focus on translating these goals in spoken english into the VRnacular language....
 

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Now what's this other window here?

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SCRIPT SYNTAX WINDOW
 
 

The window on your right when you are scripting is the script syntax document. 


Whenever you choose and action in the popup in the scripting window, 

it's definition and an example of it's use will show up in the script syntax window!  

This is very handy.

 

 If you read through the script syntax or look at the popups in the script window 

you'll notice the language is really broken into actions, operands, and operators.

Those three words, 'actions,operands and operators' scared me a bit when I first started wiring, along with another 'expression'.

Here's a quick glossary:

action:   Something your movie does, like panning, or moving a sprite.

trigger: a way to trigger an action like On MouseDown. the Idle trigger just does the action over and over...

operand: a special number qt knows, like the current pan angle, or the current time, or the value of a variable.

operator: one of the math symbols like + - * /

expression: a 'phrase' in vrnacular. like variable[1]+variable[2] it is usually made up of the grammar: operand-operator-operand    a gotch in vrnacular is that expressions can't have spaces in them. 


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You'll notice that 'SetPanAngle' isn't on the list of Actions.

The official list is strictly based on apple code. We find it easier to have a standard version that way.

But we also allow for synonyms. That is, an easier way of typing something in:

For example, instead of saying

SpriteTrackSetVariable you can just say

setvar

When the script writes out it will say

SpriteTrackSetVariable but it makes it easier to type in. Also, the original vrhotwires language used SetPanAngle, so we accept it...

(did you know you can add your own synonyms! see the synonyms folder for more info. That kind writes out the way you set it too! )


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 Solving for goal 1:

 "I want my movie to pan when I press a button at the bottom"

Let's just use the watermark tool to add the sprite right now, as the interface is still changing...
Add the sprite...

Now, first let's try these sprite click things:

copy this script:
 

On MouseDown Sprite 1

      SetPanAngle 99

end
 

hmm that seems to work pretty well. When I click on the sprite, I pan to 99. When I click again, nothing happens because I'm already at 99.

If I press command 'h' and look at the realtime info in vrhotwires, I can see I'm at 99.

But my sprite is a little arrow. I wanted it to pan while the little arrow is clicked. Then when I release the mouse it can stop panning.

Well this calls for a variable!
 

On MouseDown Sprite 1

           SpriteTrackSetVariable 1 1 tracktype=sprite
end

On MouseUp Sprite 1

           SpriteTrackSetVariable 1 0 tracktype=sprite
end

On Idle
       if variable[1]=1
                 setpanangle 3 delta
       endif

end
 

You don't have to define vaiables in VRNaclular before you use them.

Here, we toggle the value of variable 1 when the mouse is clicked or not clicked.

Then on idle, we check to see what the variable is set to before we decide to pan.
 
 

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EXPRESSIONS
 

I remember when I was a kid and I used some new phrase I learned at school my father would say 'what an odd expression' .
Well expressions are kind of phrases in vrnacular too.
 

The script syntax doc gives a list of actions...
        and each of those actions has paramaters.
                    So far we've only handed in constants(numbers) as paramaters (like in our SetPanAngle 3 call)
                     But anywhere that takes a number can take an expression too!

Try this one:
 

On Idle
      SetPanAngle thePanAngle+1
end

This should get your pano spinning too!

And thePanAngle is an operand.   You used an operand !

Operands can be thought of as reserved values. Imagine that quicktime has this great big room full of cubbyholes where it keeps certain values. Like the current date, or the current pan angle, or a sprite's position...

There's a list of operands in the script syntax document.

Important: In vrnacular 1.0 you cannot have any space in your expressions.

ie: you must say    SetPanAngle theMovieTime+37    and not   SetPanAngle theMovieTime + 37

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VARIATIONS ON GOAL 1
 

so what are some variations on this panning we've been doing when we click our sprite?

Well, wherever we've used pan we can replace it with FieldOfView.  This turns our button into a zoom button:

On MouseDown Sprite 1

           SpriteTrackSetVariable 1 1 tracktype=sprite
end

On MouseUp Sprite 1

           SpriteTrackSetVariable 1 0 tracktype=sprite
end

On Idle
       if variable[1]=1
                 QTVRSetFieldOfView 1 delta
       endif

end
 

And what about something with the sprite, let's give it a down state and up state...
When we click it, we'll make it shrink to 7/10ths of it's usual size...
 

On MouseDown Sprite 1

           SpriteTrackSetVariable 1 1 tracktype=sprite
           SpriteScale 0.7 0.7 tracktype=sprite spriteindex=1

end

On MouseUp Sprite 1

           SpriteTrackSetVariable 1 0 tracktype=sprite
           SpriteScale 1  1  tracktype=sprite spriteindex=1
end

Note that vrnacular seems to not like just .7 right now, but prefers if you enter 0.7

Or we could move it a bit when we click down:

On MouseDown Sprite 1

           SpriteTrackSetVariable 1 1 tracktype=sprite
           SpriteTranslate 5 5 false tracktype=sprite spriteindex=1

end

On MouseUp Sprite 1

           SpriteTrackSetVariable 1 0 tracktype=sprite
           SpriteTranslate neg5  neg5 false  tracktype=sprite spriteindex=1
end
 

Hmm... that one doesn't look too good, the track is too small.
You can resize your track from the movie info window.

We'll come back to sprite motion...
 

although you might want to try:

On Idle

            SpriteRotate 5 tracktype=sprite spriteindex=1

end

just to see that crazy spinning....
 
 
 

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There are over 100 wired actions and dozens of operands and operators... learning to script is a fairly long and complex task. But vrhotwires gives you a special advantage in that you can analyze the script of any existing wired movie.