   Porting old game from Glide to OpenGL
  GreetingsA few folks are working on aquiring a code to an old glide based flight sim.  We have a strategy on most aspects of the game which can be improved, but one area needs special attention:  it was ported to Glude (3DFX) in the last months before its release..only to have the 3DFX Glide-based Voodoo cards get cancelled within two years as the company was bought up by NVIDIA, who killed Glide.  Emulators are OK for really strong computers, but for "re-marketing", the average computer makes or breaks the acceptance of an updated version of the sim.This is a really "dummy" question, but here goes:  who knows how, or knows someone who knows how and could port the sim from Glide to OpenGL??ThanksSwampfox   
  There are driver wrappers that are *supposed* to work seamlessly to translate glide to opengl, but if you are working from source, it would probably be best to replace the glide calls with calls to opengl.One of the better Glide Wrappers;  First, Glide was not "killed" by nvidia. Those guys just bought 3dfx. Market saw to it that OpenGL and DirectX were becoming the major APIs for (3D) graphics while Glide could not succeed against them for various reasons.Second, porting a game from one code to another should be fairly straightforward. Just look at all code concerned with rendering and rewrite those code lines to use a different API instead. After all, all graphic APIs are quite similiar in how they ffed 3D data to the graphics card. Last but not least you have the advantage that Glide did not have such a long life cycle. Hence the API is not as comprehensive as OpenGL with all its extensions or Direct3D with its guaranteed feature set. This should help porting it alot [smile]   ;  Waterwalker, thanks for the excellent feedback.  I had spoken with a mid-level person at NVIDIA when they acquired 3DFX.  He was explicit when he told me to post in the forums that the Voodoo cards were not going to be manufactured, and that GLIDE would not be licensed out or used by them.  I assumed that they acquired 3DFX to insure that they wouldn’t be competition and that no one else would save them and become competition – even if NVIDIA probably had nothing to worry about due to, as you noted, other things.I had just read an overview of API which indicated, also as you have effectively noted, that GLIDE isn’t that far from OpenGL, especially as it relates to the issue of this game and as you insightfully noted, Glide did not get a chance to go too far down the development road before going off the cliff (paraphrasing).   That is good news for the direction I am taking, which I suspect you know.Recognizing that without the code in front of you, a tight answer is impossible, is it possible to ballpark a guess as to what a 1998 DOS-based flight sim ported to GLIDE might cost in man-hours to get the code converted to OpenGL??  Even a deliberately fat, 2X or 3X guess would be extremely valuable coming from an experienced programmer – in helping to build that part of a plan.  We have a handle on going to more modern terrain and object graphics, flight modeling, etc.  This porting aspect is super important to a go/no-go on further pursuit of redeveloping this sim.  Any help you can offer would be greatly appreciated.Vikato, the strategy of this game’s revival and development considers that the core demographic is likely to be a guy between ages 30-60, and won’t be someone, on the average, to have a dual-core high end computer.  Many will, but the sweet spot is not likely to support the wrapper strategy sufficiently to solve the Glide problem.  If the cross over to OpenGL can fit a model, the better way is a comprehensive DVD install without the requirement to go to fast computers.  I deliberately fly on a second mid-range speed box to stay in touch with that reality.  Thanks for the link.   ;  would you be willing to hire a consultant to take on the conversion process?   ;  Hi ibebrettThe answer is yes.  But as I mentioned, the effort towards acquiring the code is the first order of business.  A few hours on the clock with a talented programmer would likely be very useful in gaining a realistic projection for project costs.  It is tricky at this stage, as a number of things have to be stitched together at a first level until other elements come into focus.  I prefer to move forward on this working with individual programmers rather than a house.  But as you can understand, that has its pitfalls.   ;  If you ask for my humble opinion I would trash all the old code and start from scratch. Just use the old DOS code to have a look at how the actual flight model (read: physics of the aircrafts simulated) are handled. Then extract those algorithms and implement new, clean C++ classes (assuming you are looking at old C code [smile]) for the flight model. Meanwhile carefully choose graphics algorithms for rendering large terrains from high as well as from low altitude (there are even some tech docs about how they did that in MS FS around the web) and then start implementing your graphics system based around the terrain algorithm. I see no point in trying to port DOS based code using the Glide API. Today you will encounter totally different bottlenecks than you did with DOS and Glide. There is just no point in digging through heavily optimized assembler routines and fast squareroot hacks because any current compiler will produce code at least as fast as those cryptic code lines. Similarly current graphics cards have completely different bottlenecks.So my advice without any pay is to just strip algorithmic information from the old DOS code for the physics of flight. But trash everything else and start that from scratch. - it will be done in less time- it will be cleaner code- it will be easier to maintain and understand for you- it will be cheaper- ...   ;  I remember writing some Glide code years ago for a competition (didn't even enter in the end) and it'll probably be fairly simple to port to OpenGL as long as it's quite cleanly written. Glide looked a lot like a subset of OpenGL 1.0 but had a few quirks. Nothing that someone wouldn't be able to get around.However Waterwalkers suggestions of a complete re-write are good too. Unless you want it to look hopelessly outdated by todays standards you're going to want to rewrite the renderer and it's better to do that cleanly than to try to twist and contort the old one into doing what you want.Andy   ;  S! WaterWalker and NineYearCycleWW - your input is most appreciated and effective.  In my role, the key is finding the economic value between the cost of developing a new sim on a modern platform (very appealing) and fixing the 5-6 problem areas of the old game at a much lower (assumed, but not yet confirmed) cost, for a re-release.  If, as NYCycle indicates, there is hope that with elbow grease, two glitches (most likely input errors) can be fixed, the porting managed (I do suspect that the API difference may be slim since it was originally designed for OpenGL, and changed at the last minute - doh!), and some heavily funded by not utilized functions brought to life and some other goodies addressed, it being an old game won't prevent a strong sale with income justifying the investment and effort - assuming that the elbow grease delivers (at this level of my layman's knowledge, a big risk on the details - but that can change with a hands-on assessment of the code - still to be completed).  The original game is robust in its Single Player and unique Multi..and the flight modeling engine has been utilized by a friend to produce a remarkable realism far beyond the original game's FM design - took him four years because he didn't have the full code, and had to work around the error I mentioned above to insure accuracy.  NYCycle...if all other aspects could be managed, the eye candy, due to a leak of a piece of code years ago, became quite respectable.  But if we could go from 256 colors to millions, and boost the detail by about 125%, that would definitely hit the target market.  The strength of the sim will be the FM/DM.In response to a question - I intend to handle the next stage feasibility study, which started with this excellent exchange.  After that, if it looks viable, an interesting party would become involved.In all, I feel confident from the responses that I have come to the right place to find quality programming, without going to a house.I have learned so much from you guys, and I hope to talk to you privately soon.RegardsSwampfox   ;  You're welcome. I would love to see a good FS around again :)   