battleMETAL - And Yet, Somehow it all works - part 4 - Deployment Menu

Prepare for drop!

Checking my post timeline and realized that this blog series has now been running for a year, huzzah! Also, core coding of battleMETAL appears complete. The last few months have been cleaning up the map pipeline (don’t worry friends, we’ll get there…) which indicates that the main coding is stable! It does feel a little anticlimactic, so many weekends spent hammering this game together in a cave with a box of scraps….


Anyhoo, this article is about one of the in-mission menus. These menus are located in the CSQC module which is run exclusively client side. As described in a previous post about CSCQ, this menu system is brought up with the tab key (default key) after the player has connected to the server. One of these menus is the Deployment menu.


The design scope for the Deployment menu went something like this - Originally I wanted the player to be able to pick from a few different spawn points on any given mission. Previous mech games either lacked this feature or featured it loosely. 2 main impulses pushed me to implement such a feature in battleMETAL with the first being multiplayer. Originally I believed it was possible to make battleMETAL work in multiplayer as well as it did in singleplayer. Unfortunately due to engine limitations across multiple features, this was discovered to not be feasible given the time and manpower limits of myself (I’ll do a post eventually on what happened to multiplayer).


The second impetus came from adapting the multiplayer idea. I considered the Player’s ability to pick their spawn point to be a nice layer of tactical control to give the player in lieu of trying something like an open map or semi-open world. The spawn point selection also allows for levels to contain more than 1 scenario setup - the mission briefing can give clues to the player about the combat conditions at any of the spawn points. Once the player chooses their spawn point, they press the [launch] button, become the mech they chose in the Hangar menu and begin play.


So, how did the code get there? As seen in a previous article, a battleMETAL CSQC menu can be quickly spun up from the functional map. The file acts like a pseudo class where the primary menu functions for the desired menu are kept. I’ll cover the most interesting tidbit which are the deploy points.

Pictured is the Deployment menu with Deploy Points depicted as (A), (B), ( C).


To begin, when the Player connects to the Server, there’s a function call;

client_push_mapobjects()

This queries all the entities on the server that have the FL_NODE flag in their .flags member variable. When such entities are found, their data is piped to the Client via client_send_deployPoint() which bundles the relevant deploy point info into a SVC_TEMPENTITY game packet. The client then receives this data, checking its own global DEPLOY_POINTS_ACTIVE[]. This global array maps its array index to the Deploy Point Id of deploy point entities on the server. The game has an artificial limit of 32 total deploy point entities because of this (not sure if any given map needs more than 32 deploy points).


The ‘important info’ that the server sends to the client is the following:
        Deploy id - float, the assigned id number for the node ( this is not the same as the entity id)

         isActive - boolean, 1 or 0. Players can only see and use ‘isActive == true’ deploy points.

        Origin - the server-side location of the entity in game space as a vector, 'X Y Z'


Quick side note, deploy points can be given an .faction member var. The server only sends deploy points whose faction value matches the specified Player’s faction value. This is a holdover from the multiplayer functionality where originally PvP was going to be a thing.


Once the client has the list of deploy points, the next step is how to render them. I really wanted a clean and programmatic way to render any deploy points anywhere on the given map space. Other considerations included the fact the player in a singleplayer-context only really ever sees the Deployment Menu once per map (even if they die, the map just restarts). Due to this, there wasn’t a need to constantly send live updates of deploy point data to the client. Knowing this, drawing the deploy points onto the menu screen was fairly straightforward.


Of the few things that CSQC gets ‘for free’ from the framework is data about the world entity. I can’t remember in the C-code all of the vars in world that are sent over, but there’s one important set - .mins and .maxs. These two variables contain the size of world’s total bounding box, just like other entities have bounding boxes. Knowing the bounding box of the world allows us to compare entity locations to some sort of pseudo-constant for game space. Using this info, I created an algorithm for projecting a map coordinate onto a 2D UI panel.

1. Find the map’s total size
1. Take the mins value as a positive number and add the maxs value
2. Find the center of this new size
2. Take the mins value as a positive number, then divide it over the total size
1. This returns a percentage value ( see where I’m going here?)
3. Apply the percentage to the UI panel’s screen size
4. profit.

This algorithm allows us to display any game coordinates onto any-sized 2D space and you can see this functionality on the Briefing menu as well. Nav Points are player guide posts for navigating around the map and the same algorithm renders these points onto the Briefing menu just like the Deployment menu. Now that the Player can see where on the map a Deploy Point will place them, the next part is spawning the Player at the point they have chosen. When the player clicks the Launch button in the upper right-hand corner, the CSQC fires off a message back to the server. This message contains the player’s chosen mech, the mech’s equipment id’s, and the Deploy Point to spawn at.


When the Server receives this message, it goes and looks for the desired Deploy Point, and if it finds the point, will then move the Player to that point. The fallback scenario is that the Deploy Point is not found, so the code defaults to the map object Info Player Start which every map needs regardless of usage. That’s all I have for this post, an interesting small feature that was fun to implement and fairly unique for Quake mods. There’s probably some refactoring that could be done on the algorithm but I figure its low-cost enough to stay as it is.

battleMETAL - Quick update 4/15/2019

Where the hell have you been? 

I know I know, I'm really bad at maintaining a blog. So I've been busy with a slice of life, some major tech fighting with battleMETAL (oh we'll get into it soon), and starting a new job soon. I do want to return to the 'METAL Monday formula, its just that blog writing was cut from the schedule because it was something that could be sacrificed. I'll return to blog posts on May 6th, 2019 and we'll keep diving into the bucket of fun that is battleMETAL. 

In the mean time, the game itself is pretty much feature complete and I've moved onto level generation. I have a tentative Beta release date of Q3 2019, and then we'll see how things look from there. Stand fast, DEAD HANDS, your activation is pending.

 

battleMETAL - And Yet, Somehow it all works - part 3 - Animatics

Quite an animated conversation

One of the feature’s I wanted to exist in battleMETAL was that of ‘animatics.’ For background, an ‘animatic’ is like a glorified slideshow. These are usually defined as a series of static images displayed in a sequenced order - like a super slow animation. Why would battleMETAL need these exactly? Why for character transmissions of course. I wanted characters to be able to talk at the player, or about the player to other characters in a way that player could visually see and understand. Radio transmissions that don’t show some sort of image are hard to follow in the ebb/flow of a video game. The concept of a ‘radio operator character’ for players to interact with is also a long-established mechanic in gaming.


Part of the original scope of battleMETAL was that the player won’t do any interacting with characters outside of combat. This was mainly due to time and resource constraints, but also because of the story and who the player is in this world. However, the player still needs some things to go off of when playing the game, so I felt that I could implement workable animatics to cover this gap. The system I finished is ‘good enough’ but probably could use some refactoring to make it ‘best’.


I started with CSQC, the animatics being an entirely client-side event, in my mind. I created a short set of api functions to handle the flow of the animatic system. The overall design is something along the lines of:
 
    Receive event from server
    Load animation file
    Validate file
    Setup playback variables
    Render frame 1 
    Render next frame
    End playback


The kick off is the server sending a command to the client to begin an animatic event. Quake was designed from ground up as a client-server game even in single player. Single Player in vanilla Quake is just a local game server with a max player count of 1. So even though battleMETAL only has 1 player in its server, the code still treats that player like any other remote-connect client in the code, which I think is a good thing. On the server, I created a custom map object, event_animatic that can be triggered by player touch or by other map objects, which sends a command to the target client to begin the animatic.


When the player’s CSQC receives the command, in this case changing the player’s “state” variable to _ANIMATIC, the CSQC begins the playback of the animatic. First step is loading the file. I decided that storing animatics in plaintext files was super handy both for readability and performance. The game engine doesn’t need to keep possibly dozens of animatic scripts in memory during gameplay, and because animatics are a low-delta event with no read/write commands, having the game load them from text files seemed like a good approach. I’ve always enjoyed the JSON syntax for data storage, considering it a better alternative to XML. Leveraging the Darkplaces source port’s ability to parse text files, I whipped up a crude JSON-style parsing function. Besides, its always fun making your file extensions.

So in test.anim we see the following:

{
  'music' : ,
  'nomusic' : 0,
  'backimg' : ,
  'trans' : ,
}

The first { } is always the ‘metadata’ tags for the animatic file. Music is which sound you want to play when the entire animatic starts up, and this will play until the end of the animatic. NoMusic will shut off any CD music playing in the background ( don’t worry, it’ll resume the stopped music when the animatic finishes). BackImg is if you want 1 background image to be rendered beneath all subsequent image frames. Finally, Trans is for ‘transparency’, setting the global alpha value of the animatic during playback. These values are then stored in a 1-dimensional string array labelled simply named ANM_META_DATA. Once the metadata is loaded the text parser expects frame data to come next. Frames are defined by { } as well, and there’s no true limit, for the sake of brevity I imposed a 20 frame max (do you really need moar?).


{
  'image' : gfx/hud/target_box.png,
   'pos' : 0.79 0.225,
   'size' : 0.05 0.05,
   'sound' : sound/anim/t1m4_lineb.ogg,
   'text' : ,
   'alpha' : 0.85,
   'color' : 1 0 0,
   'text_color' : 0 0 0,
   'time' : 3,
}

Image is which image you want this frame to display, and you can set it to null / empty.

Pos is ‘screen position’ important: this is done in percentage of screen to make sure that the coordinates are screen-size agnostic.

Size is the size of the image. important: this is done in percentage of screen to make sure that the coordinates are screen-size agnostic.

Sound is the sound file you want to play on this frame. Its non-looping, and is not clipped by any sound on the next frame, so playback overlap is a risk here.

Text is any text you want rendered, I have this hardcoded to be rendered at the bottom of the screen and centered.

Alpha is the transparency of the frame.

Color is the color-tint you want to apply to the frame image and text. RGB values are in vector format between 0.001 - 1.0 for each color.

Text_color same as Color but overrides the color for the text.

Time how many seconds to render the frame for.


In addition to these tags, the code automatically does a fade-in/fade-out effect for each frame but I’m still on the fence if this is necessary or not. When the text parser reads these tags into the code, the frame reference number is used as the primary key for a series of arrays. I’m not particularly happy with this solution but I’ve chalked it up to the roughness of Quake C more than anything else….

string ANM_FRAME_IMG[20];
string ANM_FRAME_SND[20];
float ANM_FRAME_TIM[20];
vector ANM_FRAME_POS[20];
vector ANM_FRAME_SIZE[20];
string ANM_FRAME_MSG[20];
float ANM_FRAME_ALPHA[20];
vector ANM_FRAME_COLOR[20];
vector ANM_FRAME_TXT_CLR[20];


Did I mention that any sort of collections are non-existent in Quake C?

The outcome for all this is a simple but working system for achieving cutscenes and character transmissions for battleMETAL. There’s still some refinement to be had mostly due to a lack of use and testing of the code, but as it stands I’ve tested that the code works at all.

battleMETAL - And Yet, Somehow it all works - part 2 - HUD

Heads up!?

Now that we’re sort of familiar with CSQC and what its about, we can take a look at the HUD for battleMETAL. There were 2 distinct phases to arriving at the HUD code that is now in the game. The first step was expanding the GUI functions I had created for the in-game menus that we saw in last the article. battleMETAL’s DNA is western mech sims of the 90’s, and that genre of games loved its HUD mechanics.


a HUD from Earthsiege 2

It seems in hindsight that mastery of reading a mech’s HUD was integral to the overall gameplay experience of a mech sim, given how much information is being sent to the player. One of my opinions as to why mech games lost market share over time was their built-in complexity that scares away newcomers, much like how Starcraft II today.

My first attempt at a HUD system was to take the generic GUI functions I had made, and craft a single HUD for each mech. The entry point for the HUD system was and is a single function call in CSQC_update_view(). I pass the player unit type to the client, and if that unit type is ‘mech’ then it runs the hud_frame() function. In the first system, I created HUDs as entity objects in CSQC, believing it to be the easiest way to hold data and functions for each HUD. You can kinda see the madness here on this github link to the battleMETAL project. Each HUD object implemented the same ‘soft’ interface of each hud element function, along with an initializer function that setup each object.

Now, in a more modern engine or code base, this isn’t exactly a bad idea. A proper class object for each HUD would be a fine way of rendering the HUD. Over in Quake C land, I was not so fortunate - there’s only 1 object close to being a class, the entity, and we all know now they’re not really the same. This attempt ended up repeating a ton of boiler plate code, and overall was too unwieldy. Tacitly, I had made some out-of-scope assumptions about what the HUD should be able to accomplish as a system. It was good that I coded it in a direction towards a robust UI system, one should always code for universality. I realized later that the HUD didn’t need this universality, it didn’t need an open system for rendering layered UI graphics...it needed to be bespoke. Quake C’s limitations have a tendency to hone your design instincts to one-off solutions for each module.

The next step in coding the HUD system was to disabuse myself of trying to make an object-based, layered HUD system. Rather, I decided to reorient the design to being built up from simple functions. I realized that each mech HUD doesn’t really have unique functionality that would ever really differ from another HUD. That is to say, mech HUDs all contain the same information where the only differences are slight variety in presentation and position on-screen of the HUD elements.

It took about a weekend, but I refactored every single piece of HUD code. Rebuilt from the original pieces, I ended up with unique functions for specific pieces of the HUD. A few examples to explain what I’m getting at:

hud_renderEnergyMeter()

Each only deals with rendering a single type of HUD component. The method arguments for each also varies only by the information that each component needs for rendering. The responsibility for drawing the total HUD then shifts up to the main HUD function. This main function is named for the mech that it is supposed to go to, and I used a switch-case statement to determine which HUD is supposed to be drawn. When the player enters their mech, the server sends the mech’s id number to the client, and the switch-case statement selects the function by mech id.

Therefore, any given HUD main function becomes a short list of HUD component functions, the only important data that matters is the on-screen location of the HUD elements and the player data. This approach even allows a little bit of flexibility. To make more unique HUD elements, the code can either encapsulate the component in just the desired HUD or add it to the HUD function library which would then allow any HUD to use it if desired. I applied this principle at least once with the renderWeapon functions.

hud_renderWeapon1

hud_renderWeapon2

Both functions take the same information but render this information in a slightly different way. We can see that each weapon is rendered atomically this way which then also allows the designer to use both styles in the same HUD. In keeping with the modular approach, this entire set of code is only called by a single entry function renderHUDFrame() which keeps coupling between the main functionality and the HUD system loose. This reduces headaches in adding new features to either system, or when changing large pieces of either system. I had a decent amount of fun bringing the HUD system to life for battleMETAL, and I think the code reflects it. Adding new HUDs is straightforward and maintainable while troubleshooting existing HUDs wont outright break too much else.