This is very very possible. Objectives and problems you have to overcome to meet this goal:
- Use Quaternions to break Gimbal Locking (happens with Matrix and Euler Angles). You can download a nice set of Quaternion functions from Ogre Engine (free download) and with some slight tweaks they will work on Source. Quaternions are basically an Up Direction (vector), and an Angle (float). There is a function called "Slerp" that will let you smoothly orient between 2 quaternions. There are multiple ways to create Quaternions using Matrices or Vectors. - You'll have to keep a new vector that saves your "gravity direction". If you want to orient automatically you'll need to constantly trace downwards along your gravity direction and based on the new Ground Normal, allow orientation or not. - Source uses AABB which means your player box will never rotate, ever. This causes a problem with your origin. When you rotate onto a wall, your origin will be much closer to the ground than before. Simply hack around this by adjusting your RenderOrigin up X units off the ground (when you are on it of course). - Jumping was one of the bigger problems I first encountered. This is better suited for orientations based on events, if you want automatic orientation based on the ground the player is on, you'll need to have multiple traces of different lengths to make sure you maintain the correct orientation. You can also trigger going to a default gravity if you are in the air too long or the ground your over is to complicated or is orienting too fast. - You'll have to orient your models correctly. Models use Euler Angles for orientation, so if you use Quaternions, you'll have to convert to Matrix and then to Euler Angles. Not such a biggy, but Euler angles were never meant for 6 degrees of freedom usage. If you want to use them, only use them in the local world space where everything is oriented at (0,0,1). Then convert to world space. - Wall collision is another big problem you will encounter. Since you won't have the luxury of using the players bounding box for tracing, you'll have to be accurate with line traces. I constantly found myself getting knocked off the ground because of odd terrain. Stairs is another wall collision problem you have to face. This requires more line traces going in your movement direction starting from the top of your player model to the middle and so on. You have to make sure you can actually move forward if not you'll get yourself stuck in the terrain. - Other Entities is the last problem. So far you've only managed the players. Now you have to manage all other entity objects. You'll have to follow the same basic principles as the player orientation depending on what your entities do. Physics entities have to all orient based on the same gravity direction, if you want each one to have it's own orientation, you'll need to work with the physics interface. This requires managing the angular velocity and linear velocity. This is more complicated, and if you can pull off the player orientation, you should be able to figure a way to do this. On Wed, Oct 14, 2009 at 3:21 PM, Adam "amckern" McKern <[email protected]>wrote: > Its possible, but very hard to get going - though i did not change the > view, i did make it so that your movement is dependent on shooting weapons > in a ZeroG environment > > http://www.nigredostudios.com/prime/screenshots/zerog0002.jpg > > -------- > Owner Nigredo Studios http://www.nigredostudios.com > > --- On Thu, 15/10/09, Tony Paloma <[email protected]> wrote: > > From: Tony Paloma <[email protected]> > Subject: Re: [hlcoders] Arbitrary Gravity Direction > To: "'Discussion of Half-Life Programming'" < > [email protected]> > Received: Thursday, 15 October, 2009, 4:08 AM > > IPhysicsEnvironment has a function called SetGravity that takes a Vector. > You can use it to set an arbitrary direction for gravity, but it will work > for VPhysics objects only. I didn't check if this information was in that > thread you posted. Sorry if it was. > > If you have an instance of VPHYSICS_INTERFACE_VERSION, you can get the > environment by: > pPhysics->GetActiveEnvironmentByIndex(0); > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of > [email protected] > Sent: Wednesday, October 14, 2009 6:39 AM > To: [email protected] > Subject: Re: [hlcoders] Arbitrary Gravity Direction > > See this thread for a discussion and partial implementation of arbitrary > gravity direction. > http://forums.steampowered.com/forums/showthread.php?t=778484 > > I never got it working entirely right, and gave up on it anyway :) > And it never did props. > > -- > This message was sent on behalf of [email protected] at openSubscriber.com > > http://www.opensubscriber.com/message/[email protected]/129248 > 43.html<http://www.opensubscriber.com/message/[email protected]/129248%0A43.html> > > _______________________________________________ > To unsubscribe, edit your list preferences, or view the list archives, > please visit: > http://list.valvesoftware.com/mailman/listinfo/hlcoders > > _______________________________________________ > To unsubscribe, edit your list preferences, or view the list archives, > please visit: > http://list.valvesoftware.com/mailman/listinfo/hlcoders > > > > > > > __________________________________________________________________________________ > Get more done like never before with Yahoo!7 Mail. > Learn more: http://au.overview.mail.yahoo.com/ > _______________________________________________ > To unsubscribe, edit your list preferences, or view the list archives, > please visit: > http://list.valvesoftware.com/mailman/listinfo/hlcoders > > _______________________________________________ To unsubscribe, edit your list preferences, or view the list archives, please visit: http://list.valvesoftware.com/mailman/listinfo/hlcoders
