Processing 1.0 - Processing Discourse - finding whether a mouse is over an image

We closed this forum 18 June 2010. It has served us well since 2005 as the ALPHA forum did before it from 2002 to 2005. New discussions are ongoing at the new URL http://forum.processing.org. You'll need to sign up and get a new user account. We're sorry about that inconvenience, but we think it's better in the long run. The content on this forum will remain online.

Index › Programming Questions & Help › Programs › finding whether a mouse is over an image

‹ Previous Topic | Next Topic ›

Pages: 1

finding whether a mouse is over an image (Read 1002 times)

dbokser YaBB Newbies Offline Posts: 4	finding whether a mouse is over an image Jan 27^th, 2008, 3:02am I'm trying to find out whether a mouse cursor (or any point) is over an image, but I'm having trouble since the image is rotating around. I can't just use if(x > corner1x && x < corner2x && y > corner1y && y < corner2y). How do I compensate for the rotation?

antiplastik YaBB Moderator Offline Posts: 699 France	Re: finding whether a mouse is over an image Reply #1 - Jan 27^th, 2008, 9:57am I guess you'll have to calculate the equation of each vertex, to determine either the cursor is inside or out. But I think 2D-picking could help, too. http://www.processinghacks.com/hacks/picking

mflux

Re: finding whether a mouse is over an image
Reply #2 - Jan 27^th, 2008, 11:44am

If you're rotating a rect and you know the coordinates of its corners (say... you've rotated the points mathematically or did screenX/Y to get the coordinates back) you can use point-in-triangle detection to figure out if the mouse is inside the space.

Try looking up sedgewick's point in triangle routine, there are many solutions out there. Think of a rotated rect as two triangles and you should be fine.

Portfolio

eskimoblood Senior Member Offline Posts: 341	Re: finding whether a mouse is over an image Reply #3 - Jan 27^th, 2008, 2:41pm If you able to calculate the coordinates of the corners you can use the awt.Polygon class to check: http://www.processinghacks.com/hacks/using-awt-s-polygon-class-to-test-for-insideness
	Andreas Köberle {eskimoblood}

dbokser YaBB Newbies Offline Posts: 4	Re: finding whether a mouse is over an image Reply #4 - Jan 28^th, 2008, 12:13am Thanks for the responses! How would I go about finding the position of the corners in world space? I'm using translate() and rotate() to move the image around.

mflux Senior Member Offline Posts: 388	Re: finding whether a mouse is over an image Reply #5 - Jan 28^th, 2008, 9:40am I would try screenX and screenY.
	Portfolio

dbokser YaBB Newbies Offline Posts: 4	Re: finding whether a mouse is over an image Reply #6 - Jan 29^th, 2008, 1:00am It worked! Thanks for all the help!

dbokser YaBB Newbies Offline Posts: 4	Re: finding whether a mouse is over an image Reply #7 - Jan 29^th, 2008, 5:35am Here's a small applet with an algorithm to find whether a point is in a triangle. http://www.davidbokser.com/private/pointInTriangle.pde

Pages: 1

‹ Previous Topic | Next Topic ›