Snapping, autoPlace and the mouse

[martynd]

Hi all,

i had problems with just trying to take a point in screen space and get a snapped point back in world space, for use in tools, until i stumbled across the autoPlace command which looked like it would solve all my problems!
So i knocked up this little test:

draggerContext
	-pressCommand "sampleContextPress"
	-cursor       "hand"
	sampleContext;

global proc sampleContextPress()
{
	float $pressPosition[] = `draggerContext -query -anchorPoint sampleContext`;
	print ("Press: " + $pressPosition[0] + " " + $pressPosition[1] + " " + $pressPosition[2] + "n");
string $sphere[] = `sphere`;
float $position[] = `autoPlace -um`;
move -relative $position[0] $position[1] $position[2] $sphere[0];
}

setToolTo sampleContext;

Thas makes a sphere and moves it using autoPlace, based on where you click. The problem you will find tho is that it doesnt work! the spheres end up offset.
This offset is the vector from the top left of the desktop to the top left of the main 3d window. So autoPlace basically takes mouse coordinates in desktop space.
I cant find any way of accounting for this in MEL or the api.

Does anyone have any ideas? tools like the polyCreateFace must do this properly?

[martynd]

No ideas? Can anyone try this and tell me if it does the same thing on their computers? or on any other OS than Windows??
M.

[daniels]

I could reproduce the behaviour on Maya 5.01 onWindows XP. The offset is as you described.

Workaround suggestion:
I would recommend to move the cursor before calling autoPlace. So autoPlace will use the correct cursor position for its calculation. Then move the cursor back after calling autoPlace.

Required Plugins:
Use the Maya API to create a MEL command that calculates the offset (using the position of the window under the cursor... GetCursoPos(), WindowFromPoint(), GetWindowRect() should do the trick on Windows) and returns it.
Use the Maya API to create a MEL command that allows to move the cursor on screen (absolute or relative, maybe also show/hide it).

Daniel

PS:
Please read you private messages. I'm facing the same problem with MPx3dModelView as you had.

[shelly]

Hi guys,
did you solve the problem?I'm having the same problems with the mouse..moreover I'm new at programming in Maya and I'm getting a bit confused...but this looks like a bug to me...if you notice autoplace only returns 2 values, $position[1] is always 0 even if you click random in persp..so that all the spheres created have y=0 no matter where the mouse was...
in top view where it's ok if y is 0 when you use autoplace it does not create the object in the mouse position anyway...now..trying to avoid the offset using the camera window is a good idea..Did you succed with the c++ api that you mentioned?I'm very curious..
cheers

[joojaa]

Its not a bug, ts a feature the ground plane (the visible grid) is the default working plane on any perspective views. You can offcourse makeany new plane or any other shape if you make a object live... The default setting makes placing thing on ground easier.

[shelly]

I see..but point is the autoPlace command help says that autoPlace places an object on the coordinates 0,0,0..in the center of the view...it has a flag that is -um wich means 'use mouse' wich should place the object where the mouse is....
according to help:

-um/useMouse Use the current mouse position rather than the centre of the active view.

so one would expect that the object is placed where you click, wich is I think what MartinD expected from command when he wrote this lines
"
string $sphere[] = sphere;
float $position[] = autoPlace -um;
move -relative $position[0] $position[1] $position[2] $sphere[0];

"
...if one axis is always set to zero becouse autoPlace -um always returns 2 coordinates as if it worked on a 2d enviroment..this is the bug to me ... you'll never get the correct placement of the object...do you get my point? be patient as I told you I'm new at this...

[joojaa]

But you cant define a 3d point by clicking on a flat viewport unless you do conclusions like this! Since the object can be at any distance in 3d. You click on 2d projection! so theres no telling how deep in that direction you want to come.

If you think its a bug then sure it might be tought of one. But id see a random depth placemant as even more annoying. A computer cant conjure info it doesent have.

[shelly]

I solved it like this anyway ))

draggerContext
-pressCommand "sampleContextPress"
-sp "world"
-cursor "hand"
sampleContext;

global proc sampleContextPress()
{
float $pressPosition[] = draggerContext -query -anchorPoint sampleContext4;
print ("Press: " + $pressPosition[0] + " " + $pressPosition[1] + " " + $pressPosition[2] + "n");
string $sphere[] = sphere;

move -relative $pressPosition[0] $pressPosition[1] $pressPosition[2] $sphere[0];

}

setToolTo sampleContext4;

[shelly]

I mean problem was that draggerContext by default takes screen coordinates in anchorPoint...with the flag -sp "world" you tell it to use world coordinates...i think autoPlace does the same...if you use autoPlace with camera window full screen it works fine...

cheers )) and thank you a lot for you help:))

[curiouskit]

Just a random note on this. The return value of the query for this will be in centimeters, if you the end user use anything but centimeters you will need to do a conversion before this will work as expected.