Re: Polygon geometry - any suggestions?
Thanks I'll test it - whatever it does :) ___ use-revolution mailing list use-revolution@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-revolution
Polygon geometry - any suggestions?
I am working with maps and geo-tagging media files - as part of this I need to work out if a point is within an area - simplest case a polygon, but this could be a simple volume - that is a polygon extruded to the ground. The coordinates are latitude and longitude in degrees - with heights in metres - so a 3D point looks like: -0.1055509873752101,51.56310290997875,23 and a simple volume based on a polygon (23 metres high) extruded to the ground looks like this: -0.1055509873752101,51.56310290997875,23 -0.1057556880140851,51.56295803562467,23 -0.1056108205764588,51.56284448695596,23 -0.1055509873752101,51.56310290997875,23 The question is how to determine if a point is within this polygon / volume. What approach to take? has anyone done this before in Rev? Ideally there would be a simple algorithm - but so far I can't find one - so a basic hack would be to translate the geometry to screen based pixels and construct Rev polygons and then use the built in within(object, point) function? Not the fastest and definitely hacky - any suggestions regarding a better way? ___ use-revolution mailing list use-revolution@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-revolution
Re: Polygon geometry - any suggestions?
Don't know if this would work out for you, but you can have a simple image that you check the color of pixels to tell where you are. I used that method in this thing I did: http://staff.funnygarbage.com/colin/track/track.mov The stack is here: http://staff.funnygarbage.com/colin/track.rev.zip Once we did a golf game, where you had to hit the ball onto various greens (using perspective 3D), and by checking the color of the pixel you landed on it was possible to know whether you were on a green, and on which one, even if the areas were broken up into multiple strange shaped blobs. ___ use-revolution mailing list use-revolution@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-revolution
Re: Polygon geometry - any suggestions?
Interesting idea - would be more flexible and powerful too. Still I'd rather do simple text based geometry as eventually this should be a CGI? This is the only one I've found so far - does my head in to look at it :) - Within Polygon Algorithmhttp://www.ecse.rpi.edu/Homepages/wrf/Research/Short_Notes/pnpoly.html#The%20Method ___ use-revolution mailing list use-revolution@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-revolution
Polygon geometry - any suggestions?
Hello David, I use the following function (sorry, but I forgot, who created it) function ptInPoly p, pts put false into inside put item 1 of p into xt put item 2 of p into yt put item 1 of line 1 of pts into xOld put item 2 of line 1 of pts into yOld repeat with i = 2 to the number of lines in pts put item 1 of line i of pts into xNew put item 2 of line i of pts into yNew if (xNew xOld) then --flip put xOld into x1 put xNew into x2 put yOld into y1 put yNew into y2 else put xNew into x1 put xOld into x2 put yNew into y1 put yOld into y2 end if if (xNew xt) = (xt = xOld) and ((yt-y1)*(x2-x1)) ((y2- y1)*(xt-x1)) then put not inside into inside put xNew into xOld put yNew into yOld end repeat return inside end ptInPoly From: David Bovill [EMAIL PROTECTED] Subject: Polygon geometry - any suggestions? .. I am working with maps and geo-tagging media files - as part of this I need to work out if a point is within an area - simplest case a polygon, but this could be a simple volume - that is a polygon extruded to the ground. Richard ___ use-revolution mailing list use-revolution@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-revolution
polygon geometry
One thing that might help is that if you have a point P that you know is in the polygon, then For any other point Q in the polygon, the segment PQ will cross the polygon(boundary) an even number of times and for any point Q outside the polygon the segment PQ will cross the boundary an odd number of times. A special case of that is that if it is a convex polygon (P could be the loc) then PQ will not cross the boundary at all if Q is inside and PQ will cross exactly once if Q is outside. Hope this helps, - Mick PS you might have to consider PQ running along one of the boundary segments if P is not chosen so as to avoid that On May 16, 2008, at 1:00 PM, [EMAIL PROTECTED] wrote: Message: 14 Date: Fri, 16 May 2008 11:35:39 +0100 From: David Bovill [EMAIL PROTECTED] Subject: Polygon geometry - any suggestions? To: How to use Revolution use-revolution@lists.runrev.com Message-ID: [EMAIL PROTECTED] Content-Type: text/plain; charset=ISO-8859-1 I am working with maps and geo-tagging media files - as part of this I need to work out if a point is within an area - simplest case a polygon, but this could be a simple volume - that is a polygon extruded to the ground. The coordinates are latitude and longitude in degrees - with heights in metres - so a 3D point looks like: -0.1055509873752101,51.56310290997875,23 and a simple volume based on a polygon (23 metres high) extruded to the ground looks like this: -0.1055509873752101,51.56310290997875,23 -0.1057556880140851,51.56295803562467,23 -0.1056108205764588,51.56284448695596,23 -0.1055509873752101,51.56310290997875,23 The question is how to determine if a point is within this polygon / volume. What approach to take? has anyone done this before in Rev? Ideally there would be a simple algorithm - but so far I can't find one - so a basic hack would be to translate the geometry to screen based pixels and construct Rev polygons and then use the built in within(object, point) function? Not the fastest and definitely hacky - any suggestions regarding a better way? ___ use-revolution mailing list use-revolution@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-revolution
