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Index › Programming Questions & Help › Syntax Questions › getting coords from matrix stack transform
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getting coords from matrix stack transform? (Read 513 times)
ehrenk
getting coords from matrix stack transform?
May 22nd, 2008, 6:42am  
Hi there, my first post im rather new to processing and matrices.

Is there a way to get the new location of a point from a matrix stack ?
in the case of rotating a 2d polygon.

pushMatrix();
translate(center.x,center.y);
rotate(spin);
// looking for some way to store the transformed XY or XYZ coordinate here

for (int i=0; i<list.size(); i++) {
point pxy = (point) list.get(i);
pxy[i].x= transformed x;
pxy[i].y= transformed y;
}
popMatrix();

Or would one have to re-solve for this. Would seem to be unnecessary since the matrix stack should contain the information because it has solved the transform.
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« Last Edit: May 22nd, 2008, 8:47am by ehrenk »  
 
JohnG
Re: getting coords from matrix stack transform?
Reply #1 - May 22nd, 2008, 9:41am  
I think http://processing.org/reference/screenX_.html (and screenY) are just what you're looking for, they'll tell you where about on screen a certain x/y/z coordinate will appear.
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ehrenk
Re: getting coords from matrix stack transform?
Reply #2 - May 22nd, 2008, 10:36am  
Sweet thnx john. silly me.
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Manic
Re: getting coords from matrix stack transform?
Reply #3 - May 22nd, 2008, 1:11pm  
what a handy command!

does it take account of camera transformations too?
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WWW  
JohnG
Re: getting coords from matrix stack transform?
Reply #4 - May 22nd, 2008, 1:19pm  
It'll tell you were an x/y/z point will appear on screen given all the current transformations, both camera and scene.
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sw01
Re: getting coords from matrix stack transform?
Reply #5 - May 22nd, 2008, 4:22pm  
Crikes, that just saved me tons of time!  But the question is...is screenZ() about the projected image, or I should know something about my otherwise 2D monitor? Smiley
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JohnG
Re: getting coords from matrix stack transform?
Reply #6 - May 22nd, 2008, 4:44pm  
screenZ() gives the z-buffer value I think.
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