Thanks Josh. I've added the updated article to VDC: http://developer.valvesoftware.com/wiki/Think() .
I know there is a DATADESC macro to define a Think function, DEFINE_THINKFUNC. I'm not sure of what it gains you, however, and from what I've been able to tell everything works fine without it.
I'd guess that it prevents an entity from changing its mind about something every time a saved game is loaded. It's a good enough theory to be going on with.
You mention ClientThink at the beginning of the document, and then again at the end. I'd put them together.
There's actually a link down to the ClientThink heading in the HTML version. That's the best way of doing it: you don't want to less useful stuff pushing down the core information, but you do want people who need to perform a special task to be aware that the page will be useful to them.
Are you sure the Think function is called automatically at Spawn?
Yes. :-) Think is the logic_auto of entities.
I'd mention that passing 0 (some code samples I've seen use NULL) to SetNextThink will prevent a Think function from being fired again.
Good tip, I'll add that.
The code samples and explanations are perfect for how to use the Think functions and how they're based on time. Also, the more advanced example regarding the gun is a great way of showing how those functions can be expanded into something more detailed, that's not necessarily "AI". In other words, it's another use of the Think functions.
What code samples? Josh Rehm wrote:
-- [ Picked text/plain from multipart/alternative ] Some good info. I learned a bit from it. I am by no means a professional (anything), so take my comments with a grain of salt! This is all just my own little opinion. I can't speak for everyone, but to me it would seem like anyone who understands basic programming concepts, functions, and methods (member functions), should be able to realize they can call functions from anywhere (inside Think functions). I'd recommend picking a target audience that allows you to focus on explaining the purpose of the Think functions, how to use them, and write as if you're talking to them. Organize the document in such a way where it states its assumptions about the reader's knowledge, where the reader can find information about those assumptions (if they don't know those things), and then the document itself. I know there is a DATADESC macro to define a Think function, DEFINE_THINKFUNC. I'm not sure of what it gains you, however, and from what I've been able to tell everything works fine without it. However, since it exists, it may be good to understand the purpose of DATADESC so you can describe what using that macro gains you. (This would teach me something too!) Though, following what I mention in the paragraph above, I wouldn't go into a lot of detail about the purpose of DATADESC itself. You could write a separate document on that. As for AI, at most I would suggest that these functions could be used for AI, and then cover the AI in another document. Again, this keeps the document focused on the Think functions and how to use them. Elaborate a little on what "internal logic" is, as it's an important concept in terms of what a Think function is for. Something like "Think functions are used to implement your entity's internal logic, how your entity thinks. In other words, an Entity can use a think function to determine how it should react to external stimuli and its current situation. For example, an entity that uses a weapon could use a Think function to check its current ammunition stock. If its low, it would switch to another Think function that implements how it should go about finding ammunition." This could tie in well to the AI comment I made above. You mention ClientThink at the beginning of the document, and then again at the end. I'd put them together. Are you sure the Think function is called automatically at Spawn? I always thought you had to set the correct think function with SetThink, and call SetNextThink from within Spawn() to get the a Think function to fire the first time. I may be wrong here, and if so someone please correct me (I don't have the code available to test it at the moment). I'd mention that passing 0 (some code samples I've seen use NULL) to SetNextThink will prevent a Think function from being fired again. The code samples and explanations are perfect for how to use the Think functions and how they're based on time. Also, the more advanced example regarding the gun is a great way of showing how those functions can be expanded into something more detailed, that's not necessarily "AI". In other words, it's another use of the Think functions. Finally, I would elaborate a little on what you mean by "Don't put anything expensive in this function." I think it's a very useful document, especially to someone just getting started with the Source Engine. Great job! - Josh On Fri, Feb 22, 2008 at 11:56 AM, Tom Edwards <[EMAIL PROTECTED]> wrote:[ Converted text/html to text/plain ] I'm in the process of writing some programming documentation for VDC (it's a fantastic way to learn). Before I make any changes, I'd like to hear some feedback. :-) Some concerns of mine: I don't explicitly mention that you can call the functions from anywhere within a class, not just a think function. How obvious is it that you can do that? I don't mention DATADESC. I don't understand it, can't make it work, and all of my experiments worked fine without it anyway. Is it important? I don't mention AI thinking. Should I? Is it actually any good? Here's the copy. I hope you can view HTML e-mails: ------------------------------------------------------------------------------ Thinking An entity's Think() function is the "root" gateway used to run all internal logic. It is called once on spawn, with any subsequent calls decided by the programmer – happening either on a regular basis, or in response to external events. Use ClientThink()[1] to have an entity think every frame. SetNextThink() Defines when the entity next thinks. Accepts a floating point[2] value. If more than one call is made in a single execution, the new value overrides the old. void CMyEntity::Think() { Msg( "I think, therefore I am.\n" ); SetNextThink( gpGlobals->curtime + 1.0f ); // Think again in 1.0seconds } This code causes the entity to print a message to the console once per second. Note the use of gpGlobals->curtime, which returns the time at execution, and f, which tells the C++ compiler that we are submitting a floating-point value and not an integer[3]. SetThink() Changes the active think function Accepts a function pointer[4]: add '&' before the name and omit its closing parentheses. If more than one call is made in a single execution, the new value overrides the old. void CMyEntity::Think() { Msg( "I think, therefore I am.\n" ); SetThink( &CMyEntity::Think2 ); // Think with this procedure next SetNextThink( gpGlobals->curtime + 1.0f ); } void CMyEntity::Think2() { Msg( "Variety is the spice of life.\n" ); SetThink( &CMyEntity::Think ); // Think with this procedure next SetNextThink( gpGlobals->curtime + 1.0f ); } This code switches thinking between two functions. A real-world application is to change an entity between various life stages: consider a buildable gun turret[5]. One think function would run while it waits to be unpackaged, another while it is being built, another while it is active, and a fourth when it dies. Creating think functions for each discrete stage increases code stability and aids debugging. ClientThink() Thinking can also occur on the client, but its effects are limited. Additionally, only one think function is supported for each entity. void C_MyEntity::ClientThink() { DevMsg( "Don't put anything expensive in this function!\n" ); SetNextClientThink( CLIENT_THINK_ALWAYS ); // Think every frame } Some examples of client-side thinking are: Visual effects / particles VGUI screen interaction Modifying player speed (calculated on the client as well as server to avoid lag) Striders' legs snapping ropes (disabled by default) SetNextClientThink() Used to re-fire ClientThink(). In addition to normal float values, it accepts: CLIENT_THINK_ALWAYS Think on the client once every frame. Use with caution! Replaces Simulate(). CLIENT_THINK_NEVER Stop all client-side thinking without killing the entity. ===References:=== 1. http://developer.valvesoftware.com/w/index.php?title=Generalities_On_Entities&action=submit#ClientThink.28.29 2. http://en.wikipedia.org/wiki/Floating_point 3. http://en.wikipedia.org/wiki/Integer_%28computer_science%29 4. http://en.wikipedia.org/wiki/Pointer_%28computing%29 5. http://forums.gamedesign.net/viewtopic.php?t=3702 _______________________________________________ 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
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