Re: [osg-users] Beginners pain...
And you do of course know about the following tools: http://playerstage.sourceforge.net/index.php?src=gazebo http://www.pyrorobotics.org/?page=The_20Pyrobot_20Simulator They are Robot simulation environments, I think most of them use ODE. I know there are a few more, but I couldnt recall the names of them right now... /Anders On 11/16/06, antoine.rennuit <[EMAIL PROTECTED]> wrote: Hi Harald (and others), I am very much involved in physics engines for games and virtual reality, and as far as I know all physics engines come with optimized collision detection (optimization is a key feature because it is really greedy). I don't know exactely what you mean by "simulation" but if it is dynamical simulation you should have a look at http://www.ode.org/ which is the best free dynamical simulator I know - though it is far behind its commercial counterparts. It includes proper collision detection and polyarticulated rigid bodies dynamics. Another point: in most well written applications, physics (for the simulation of your robot) and rendering are isolated layers. Different functions, different packages... That makes sense and is worth keeping for general understanding of the architecture. Antoine. > Hi Marco, > > On 11/16/06, Marco Jez wrote: > > There is a good article on GameDev.net that explains how to do collision > > detection between ellipsoids and polygons. I've used it to implement > > viewer-world collision detection and it works fine: > > > > http://www.gamedev.net/reference/articles/article1026.asp > > > > The ray-polygon intersection test performed by osgUtil::IntersectVisitor is > > not enough for this kind of collision detection (unless you can model the > > collider as a point rather than as an ellipsoid). > > Heh heh, neat little trick with transforming a sphere to ellipsoid. > All we need now is an EllipsoidIntersector ;-) > > > When the project I'm working on is finished I'll be able to release my CD > > code as open source. > > Oooh what a tease. I very much look forward to that day. > > Any chance of it being a Christmas present? > > Or fat free alternative to an Easter egg ;-) > > Good luck with the project, > Robert. > ___ > osg-users mailing list > osg-users@openscenegraph.net > http://openscenegraph.net/mailman/listinfo/osg-users > http://www.openscenegraph.org/ Accédez au courrier électronique de La Poste sur www.laposte.net ou sur 3615 LAPOSTENET (0,34€ TTC /mn) 1 Giga de stockage gratuit – Antispam et antivirus intégrés ___ osg-users mailing list osg-users@openscenegraph.net http://openscenegraph.net/mailman/listinfo/osg-users http://www.openscenegraph.org/ -- Anders Backman Email:[EMAIL PROTECTED] HPC2N/VRlab Phone:+46 (0)90-786 9936 Umea university Cellular: +46 (0)70-392 64 67 S-901 87 UMEA SWEDEN Fax: +46 90-786 6126 http://www.cs.umu.se/~andersb ___ osg-users mailing list osg-users@openscenegraph.net http://openscenegraph.net/mailman/listinfo/osg-users http://www.openscenegraph.org/
Re: [osg-users] Beginners pain...
Hi Harald (and others), I am very much involved in physics engines for games and virtual reality, and as far as I know all physics engines come with optimized collision detection (optimization is a key feature because it is really greedy). I don't know exactely what you mean by "simulation" but if it is dynamical simulation you should have a look at http://www.ode.org/ which is the best free dynamical simulator I know - though it is far behind its commercial counterparts. It includes proper collision detection and polyarticulated rigid bodies dynamics. Another point: in most well written applications, physics (for the simulation of your robot) and rendering are isolated layers. Different functions, different packages... That makes sense and is worth keeping for general understanding of the architecture. Antoine. > Hi Marco, > > On 11/16/06, Marco Jez wrote: > > There is a good article on GameDev.net that explains how to do collision > > detection between ellipsoids and polygons. I've used it to implement > > viewer-world collision detection and it works fine: > > > > http://www.gamedev.net/reference/articles/article1026.asp > > > > The ray-polygon intersection test performed by osgUtil::IntersectVisitor is > > not enough for this kind of collision detection (unless you can model the > > collider as a point rather than as an ellipsoid). > > Heh heh, neat little trick with transforming a sphere to ellipsoid. > All we need now is an EllipsoidIntersector ;-) > > > When the project I'm working on is finished I'll be able to release my CD > > code as open source. > > Oooh what a tease. I very much look forward to that day. > > Any chance of it being a Christmas present? > > Or fat free alternative to an Easter egg ;-) > > Good luck with the project, > Robert. > ___ > osg-users mailing list > osg-users@openscenegraph.net > http://openscenegraph.net/mailman/listinfo/osg-users > http://www.openscenegraph.org/ Accédez au courrier électronique de La Poste sur www.laposte.net ou sur 3615 LAPOSTENET (0,34 TTC /mn) 1 Giga de stockage gratuit Antispam et antivirus intégrés ___ osg-users mailing list osg-users@openscenegraph.net http://openscenegraph.net/mailman/listinfo/osg-users http://www.openscenegraph.org/
Re: [osg-users] Beginners pain...
Hi Robert, Oooh what a tease. I very much look forward to that day. Any chance of it being a Christmas present? Actually, yes. The project, although expected to end this month, won't probably be completed before Jan 2007, but the collision detection code is just a single file and it shouldn't require heavy refactoring in order to be detached from the project's source tree. Good luck with the project, Thank you, Marco ___ osg-users mailing list osg-users@openscenegraph.net http://openscenegraph.net/mailman/listinfo/osg-users http://www.openscenegraph.org/
Re: [osg-users] Beginners pain...
Hi Marco, On 11/16/06, Marco Jez <[EMAIL PROTECTED]> wrote: There is a good article on GameDev.net that explains how to do collision detection between ellipsoids and polygons. I've used it to implement viewer-world collision detection and it works fine: http://www.gamedev.net/reference/articles/article1026.asp The ray-polygon intersection test performed by osgUtil::IntersectVisitor is not enough for this kind of collision detection (unless you can model the collider as a point rather than as an ellipsoid). Heh heh, neat little trick with transforming a sphere to ellipsoid. All we need now is an EllipsoidIntersector ;-) When the project I'm working on is finished I'll be able to release my CD code as open source. Oooh what a tease. I very much look forward to that day. Any chance of it being a Christmas present? Or fat free alternative to an Easter egg ;-) Good luck with the project, Robert. ___ osg-users mailing list osg-users@openscenegraph.net http://openscenegraph.net/mailman/listinfo/osg-users http://www.openscenegraph.org/
Re: [osg-users] Beginners pain...
Hi Harald and Andreas, Simple collision detection is easy: You can do that with an intersect-visitor and test if a given beam intersects something. This way you could simulate a sensor that looks at exactly one direction. There are more sophisticated methods, but others will have to comment on that. There is a good article on GameDev.net that explains how to do collision detection between ellipsoids and polygons. I've used it to implement viewer-world collision detection and it works fine: http://www.gamedev.net/reference/articles/article1026.asp The ray-polygon intersection test performed by osgUtil::IntersectVisitor is not enough for this kind of collision detection (unless you can model the collider as a point rather than as an ellipsoid). When the project I'm working on is finished I'll be able to release my CD code as open source. Cheers, Marco ___ osg-users mailing list osg-users@openscenegraph.net http://openscenegraph.net/mailman/listinfo/osg-users http://www.openscenegraph.org/
Re: [osg-users] Beginners pain...
Hi Harald, I'll add a little, but since Andreas hasalready answer most of your questions better than I could I just add a few extras. On 11/16/06, harald graef <[EMAIL PROTECTED]> wrote: - how can I do collision detection? You have a variety of options, in OSG-1.2 you'll find the osgUtil::IntersectVisitor & PickVisitor that both support line segment intersections with the scene. In the CVS version of the OSG I have began working on a more general purpose class for doing intersection testing, which you'll find in osgUtil/IntersectionVisitor. This visitor allows you to attach generic Intersector objects, and these may take the form of LineSegmentIntersector, PolytopeIntersector or IntersectorGroup. By the end of the both their will be a PlaneIntersector too. The PolytopeIntersector doesn't yet support fine grained intersections with triangles and lines yet but this will come in time for OSG-1.3. There are also 3rd party specialist collision detection libraries that you could search for and integrate with the OSG. Depending on your needs this might be the route you'd want to go done. Have a search through the mailing list archives to see some options. This is a crucial point. Putting some sensors to the virtual robot and gainig - are there invisible objects? A sensor detection-field can simply be modeled as mesh, which is invisible. Actions are only taken, when the detection-field-mesh collides with something. The way to do this is to create a polygon mesh (in the form of an osg::Geometry) and make its parents NodeMask with a mask that the cull traversal doesn't pass so its not seen. But have the intesection traversal accept this mask. This way you get the intersections but don't see the object. Robert. ___ osg-users mailing list osg-users@openscenegraph.net http://openscenegraph.net/mailman/listinfo/osg-users http://www.openscenegraph.org/
Re: [osg-users] Beginners pain...
Hi, I can only answer parts of your questions and hope others will chime in. harald graef schrieb: Hi osg-users, I intend to write a simulator for my robot projects (http://home.arcor.de/harald.graef). Fumbling around with the code since some time it was not possible to solve the "virtual world problem". Since now I used th Crystal Space Engine, but it is more intended as a gaming engine - very powerfull, but very complicated. Even when you are not new to software development. To come to the question: OSG looks a lot more compatible to my understanding of programming, but - how can I do collision detection? This is a crucial point. Putting some sensors to the virtual robot and gainig information about the things in front of it is one of the core questions. I didn't find any example for CD. Simple collision detection is easy: You can do that with an intersect-visitor and test if a given beam intersects something. This way you could simulate a sensor that looks at exactly one direction. There are more sophisticated methods, but others will have to comment on that. Maybe (if your sensors work exactly in one direction) what I said is already enough for you. - are there invisible objects? A sensor detection-field can simply be modeled as mesh, which is invisible. Actions are only taken, when the detection-field-mesh collides with something. You can set alpha to zero to make things invisible or set the node-mask to zero. If you set alpha to zero, things are still pickable, if you set the node-mask to zero an intersect-visitor will not find it. I don´t understand your detection-field mesh well enough to tell you which to use. - Does OSG run on weak hardware? If ever, I finish this simulator, I want to give it to the robo-builder community. I'm afraid, that many of this people do work with older computers. I'm not very familiar with Open GL - is hardware acceleration a really need (sorry for that question)? As my customers are schools I can tell you the following: OSG runs quite well on weak hardware as long as there is an hardware-accelerated graphics-card. My application even runs on a pentium mmx 233 MHz with a frame-rate of about 10 Hz. If you don´t have hardware-acceleration you can still use it (not well, of course) if you have a fast processor: I develop the linux-port of my application in vmware which has no hardware-accelleration. This runs about 10 Hz or so, too. If you keep your app simple you will get the needed 60 Hz easily with a 500 MHz processor and a 32 mb graphics-adapter. But be aware of the fact that _all_ openGL applications will crash badly if the openGL driver is crappy. I had to change some GraphicsAdapters (buy new ones for about 15 Euro) at my school and advise other customers to do so, too. I researched about a year ago which library to use for my project and never ever regretted to have chosen OpenSceneGraph. It is extremly well designed. At first I was a bit sceptical because of the lack of documentation, but I found that the design is so well that most of the time you don´t need any documentation. The examples and the source and the help on this list are usually better that most documentation for other projects. You will certainly be able to do the collision detection you need, though maybe not "out of the box". Regards, Andreas Thanks a lot. Suggestions about robot-simulation, or the difference between a solder iron and a computer keyboard are very welcome. Harald __ "Ein Herz für Kinder" - Ihre Spende hilft! Aktion: www.deutschlandsegelt.de Unser Dankeschön: Ihr Name auf dem Segel der 1. deutschen America's Cup-Yacht! ___ osg-users mailing list osg-users@openscenegraph.net http://openscenegraph.net/mailman/listinfo/osg-users http://www.openscenegraph.org/ ___ osg-users mailing list osg-users@openscenegraph.net http://openscenegraph.net/mailman/listinfo/osg-users http://www.openscenegraph.org/
[osg-users] Beginners pain...
Hi osg-users, I intend to write a simulator for my robot projects (http://home.arcor.de/harald.graef). Fumbling around with the code since some time it was not possible to solve the "virtual world problem". Since now I used th Crystal Space Engine, but it is more intended as a gaming engine - very powerfull, but very complicated. Even when you are not new to software development. To come to the question: OSG looks a lot more compatible to my understanding of programming, but - how can I do collision detection? This is a crucial point. Putting some sensors to the virtual robot and gainig information about the things in front of it is one of the core questions. I didn't find any example for CD. - are there invisible objects? A sensor detection-field can simply be modeled as mesh, which is invisible. Actions are only taken, when the detection-field-mesh collides with something. - Does OSG run on weak hardware? If ever, I finish this simulator, I want to give it to the robo-builder community. I'm afraid, that many of this people do work with older computers. I'm not very familiar with Open GL - is hardware acceleration a really need (sorry for that question)? Thanks a lot. Suggestions about robot-simulation, or the difference between a solder iron and a computer keyboard are very welcome. Harald __ "Ein Herz für Kinder" - Ihre Spende hilft! Aktion: www.deutschlandsegelt.de Unser Dankeschön: Ihr Name auf dem Segel der 1. deutschen America's Cup-Yacht! ___ osg-users mailing list osg-users@openscenegraph.net http://openscenegraph.net/mailman/listinfo/osg-users http://www.openscenegraph.org/
