Game Development Community

Object IDs and Picking -- How do I know what I clicked

by Matthew "Ashteth" Kee · in Torque Game Builder · 03/06/2005 (11:48 am) · 1 replies

I presume that picking in Torque works someting like it does in OpenGL. Looking at the manual, if I use the function:

fxSceneGraph2D::pickPoint()

It should return a list of object IDs beneath a given point. My question is: How do I convert an object ID back into an object, or alternatively can I set the object ID of something myself so that I know what I got back?
NextNext Thread
PrevPrevious Thread
More from Torque Game Builder


Associate Melv May
#1
03/06/2005 (11:58 am)
The good thing is that you don't need to do any conversion at all. Here's how it works...

If you create an object like this...
%obj = new fxStaticSprite2D();
...you can do this...
echo( %obj.getId() );

This is will return the objects internal ID that's used by T2D. Assuming this number is "1234", you can still do stuff like this...
1234.setPosition( "10 20" );
1234.setSize( 40 );
... which is cool. What this means that the object-IDs that the pick-routines return (as do other functions), can be used directly so I can do this...
// Pick a point.
%pickList = myScene.pickPoint("5 10");

// Get Pick Count.
%pickCount = getWordCount(%pickList) 

// Finish if we didn't pick anything.
if ( %pickCount == 0 ) return;

for ( %n = 0; %n < %pickCount; %n++ )
{
    // Fetch Object.
    %obj = getWord( %pickList, %n );
    // Dump where object is actually positioned.
    echo( "We picked object whose position is" SPC %obj.getPosition() );
}

... and we can do this because "%obj" contains the ID and it can be used as the object itself!

One thing to add is that the picking routines use the collision-polygon which defaults to the same size as the bounding-box. It does this because it uses the same swept-polygon system to pick a point, area or line.

- Melv.