cloudraven - Developer IT

Deterministic replay in a modern game

- by cloudraven

I am doing a study in modern games graphics, and as part of the study it would be really helpful to be able to replay a sequence in the game multiple times. For example, recording a series of inputs to get the exact video sequences, but being able to replay them in different computers or different graphics configurations. I want to do this study with a couple of existing commercial games with sophisticated graphics (something released in the last 1 or 2 years if possible). I was thinking on hooking with detours or something similar, calls to time() or srand() to fix all pseudo-number generated results. It would be ideal to have a general solution that works with any game. Since admittedly that is pretty ambitious, I would be happy just having 2 or 3 games in which it is known that I can get deterministic output for a given input. In the end, I will be comparing video output, so I want to avoid noise generated by differences on each execution caused by non-determinism. Any sugestions?

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Using glReadBuffer returns black image instead of the actual image only on Intel cards

- by cloudraven

I have this piece of code glReadBuffer( GL_FRONT ); glReadPixels( 0, 0, width, height, GL_RGB, GL_UNSIGNED_BYTE, buffer ); Which works just perfectly in all the Nvidia and AMD GPUs I have tried, but it fails in almost every single Intel built-in video that I have tried. It actually works in a very old 945GME, but fails in all the others. Instead of getting a screenshot I am actually getting a black screen. If it helps, I am working with the Doom3 Engine, and that code is derived from the built-in screen capture code. By the way, even with the original game I cannot do screen capture on those intel devices anyway. My guess is that they are not implementing the standard correctly or something. Is there a workaround for this?

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Using glReadBuffer/glReadPixels returns black image instead of the actual image only on Intel cards

- by cloudraven

I have this piece of code glReadBuffer( GL_FRONT ); glReadPixels( 0, 0, width, height, GL_RGB, GL_UNSIGNED_BYTE, buffer ); Which works just perfectly in all the Nvidia and AMD GPUs I have tried, but it fails in almost every single Intel built-in video that I have tried. It actually works in a very old 945GME, but fails in all the others. Instead of getting a screenshot I am actually getting a black screen. If it helps, I am working with the Doom3 Engine, and that code is derived from the built-in screen capture code. By the way, even with the original game I cannot do screen capture on those intel devices anyway. My guess is that they are not implementing the standard correctly or something. Is there a workaround for this?

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How to capture the screen in DirectX 9 to a raw bitmap in memory without using D3DXSaveSurfaceToFile

- by cloudraven

I know that in OpenGL I can do something like this glReadBuffer( GL_FRONT ); glReadPixels( 0, 0, _width, _height, GL_RGB, GL_UNSIGNED_BYTE, _buffer ); And its pretty fast, I get the raw bitmap in _buffer. When I try to do this in DirectX. Assuming that I have a D3DDevice object I can do something like this if (SUCCEEDED(D3DDevice->GetBackBuffer(0, 0, D3DBACKBUFFER_TYPE_MONO, &pBackbuffer))) { HResult hr = D3DXSaveSurfaceToFileA(filename, D3DXIFF_BMP, pBackbuffer, NULL, NULL); But D3DXSaveSurfaceToFile is pretty slow, and I don't need to write the capture to disk anyway, so I was wondering if there was a faster way to do this

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record and replay directinput events

- by cloudraven

I am trying to build a record and replay system for a couple of games. I was wondering if I can make a general replay engine using directinput rather than doing an specific implementation for each game. Recording DirectInput events doesn't seem to be that much of a problem, but I don't know if there is a way to play them back. My question is, is there a way to feed DirectInput events from a log and make DirectInput believe that they came from mouse/joystick/keyboard? I assume it is unlikely, but if there is a way I would be interested in learning about it.

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Is there any guarantee about the graphical output of different GPUs in DirectX?

- by cloudraven

Let's say that I run the same game in two different computers with different GPUs. If for example they are both certified for DirectX 10. Is there a guarantee that the output for a given program (game) is going to be the same regardless the manufacturer or model of the GPU? I am assuming the configurable settings are exactly the same in both cases. I heard that it is not the case for DirectX 9 and older, but that it is true for DirectX 10. If someone could provide a source confirming or denying it, it would be great. Also what is the guarantee offered. Will the output be exactly the same or just perceptually the same to the human eye?

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In Protobuf-net how can I pass an array of type object with objects of different types inside, knowi

- by cloudraven

I am trying to migrate existing code that uses XmlSerializer to protobuf-net due to the increased performance it offers, however I am having problems with this specific case. I have an object[] that includes parameters that are going to be sent to a remote host (sort of a custom mini rpc facility). I know the set of types from which these parameters can be, but I cannot tell in advance in which order they are going to be sent. I have three constraints. The first is that I am running in Compact Framework, so I need something that works there. Second, as I mentioned performance is a big concern (on the serializing side) so I would rather avoid using a lot of reflection there if possible. And the most important is that I care about the order in which this parameters were sent. Using XmlSerializer it was easy just adding XmlInclude, but for fields there is nothing equivalent as far as I know in Protobuf-net. So, is there a way to do this? Here is a simplified example. [Serializable] [XmlInclude(typeof(MyType1)), XmlInclude(typeof(MyType2)), XmlInclude(typeof(MyType3)) public class Message() { public object[] parameters; public Message(object[] parms) { parameters = parms; } } Message m = new Message(new object[] {MyType1(), 33, "test", new MyType3(), new MyType3()}); MemoryStream ms = new MemoryStream(); XmlSerializer xml = new XmlSerializer(typeof(Message)); xml.Serialize(ms,xml); That will just work with XmlSerializer, but if I try to convert it to protobuf-net I will get a "No default encoding for Object" message. The best I came up with is to use generics and [ProtoInclude] as seen in this example. Since I can have different object types within the array this doesn't quite make it. I added a generic List for each potential type and a property with [ProtoIgnore] with type object[] to add them and get them. I have to use reflection when adding them (to know in which array to put each item) which is not desirable and I still can't preserve the ordering as I just extract all the items on each list one by one and put them into a new object[] array on the property get. I wonder if there is a way to accomplish this?

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Protocol buffer deserialization and a dynamically loaded DLL in Compact Framework

- by cloudraven

I saw a question related to this on the full framework here. Since it seems to have stayed unresolved for quite a while and this is for the compact framework, I though it would be better to create a new question for it. I want to deserialize types for which I am loading assemblies dynamically (with Assembly.LoadFrom) and I am getting a "Unable to identify known-type for ProtoIncludeAttribute" error. In the related question I mentioned, it was hinted that hooking AppDomain.AssemblyResolve event would help solving the problem. It makes sense for the full framework, but that event is not available in the CF. I wonder if there is a way to do this with CF. The structures I am using look a lot like this and all the classes required for deserialization are loaded from the same Assembly. If the assembly is referenced instead of dynamically loaded it works fine, but fails if done dynamically.

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merging two tables, while applying aggregates on the duplicates (max,min and sum)

- by cloudraven

I have a table (let's call it log) with a few millions of records. Among the fields I have Id, Count, FirstHit, LastHit. Id - The record id Count - number of times this Id has been reported FirstHit - earliest timestamp with which this Id was reported LastHit - latest timestamp with which this Id was reported This table only has one record for any given Id Everyday I get into another table (let's call it feed) with around half a million records with these fields among many others: Id Timestamp - Entry date and time. This table can have many records for the same id What I want to do is to update log in the following way. Count - log count value, plus the count() of records for that id found in feed FirstHit - the earliest of the current value in log or the minimum value in feed for that id LastHit - the latest of the current value in log or the maximum value in feed for that id. It should be noticed that many of the ids in feed are already in log. The simple thing that worked is to create a temporary table and insert into it the union of both as in Select Id, Min(Timestamp) As FirstHit, MAX(Timestamp) as LastHit, Count(*) as Count FROM feed GROUP BY Id UNION ALL Select Id, FirstHit,LastHit,Count FROM log; From that temporary table I do a select that aggregates Min(firsthit), max(lasthit) and sum(Count) Select Id, Min(FirstHit),Max(LastHit),Sum(Count) FROM @temp GROUP BY Id; and that gives me the end result. I could then delete everything from log and replace it with everything with temp, or craft an update for the common records and insert the new ones. However, I think both are highly inefficient. Is there a more efficient way of doing this. Perhaps doing the update in place in the log table?

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