fragglet / sdl-sopwith Goto Github PK

Support for cmd line args such as -host 23513 (port number) and -join 88.88.88.88:23513 (host:port).

Just noticed this while playing. Probably got broken by the change in #12.

In vanilla Sopwith when you complete a level, your remaining planes get counted down and you get rewarded with points - so that there's a bonus if you manage to avoid being shot down. The code that does this is in swrestart() but it appears to be broken - we do the pause but don't update the screen. And then, we reset the score anyway (#20).

The purple heart medal is awarded if you successfully return to base while wounded, regardless of how the plane became wounded. It seems a bit dubious to award it as a result of arguably your own clumsiness, but also sets up a rather perverse incentive where you get rewarded for deliberately damaging your own plane through eg. flying through the ox at the end of the runway. I think we should probably limit it to actual combat damage

If the window is minimized or resized on a menu screen, we need to redraw the screen to refresh it. This currently doesn't happen.

The codebase still depends on SDL 1.2, which is long obsolete. Transitioning to SDL2 should allow several nice enhancements, such as arbitrary window scaling using hardware acceleration.

This is required on Flathub and is consumed by e.g. KDE Discover, GNOME Software, …

https://github.com/wjt/flathub/blob/io.github.fragglet.sdl-sopwith/io.github.fragglet.sdl_sopwith.metainfo.xml is my work-in-progress. It may need revising in light of #16.

It's confusing to users that the close button doesn't work; it should exit the game.

DOS sopwith2 had joystick support and SDL provides the API

I checked both Sopwith 2 and Author's Edition and neither of them reset the score. It seemed that we picked up the current reset-score behavior at some point by mistake.

https://github.com/fragglet/sdl-sopwith/blob/trunk/src/swasynio.c#L164

Medals get awarded only after a successful return to base, which makes sense. However, as soon as you crash the plane a single time and lose a life, you lose all the medals you were awarded. It seems rather harsh. A less harsh approach might be that you keep the medals for the duration of the level; this is consistent with the score, which resets to zero at the start of each new level.

@creichen - through some googling I think you were the original implementer of the medals feature, a long long time ago (it finally made it into a release last year when I revived the project!). Do you have any opinions on changing the behavior?

When the game is over it is supposed to return to the title screen, but because of problems with emscripten's version of longjmp() it just crashes instead

The idea here is to add a toggle that lets you select between Sopwith 1 and 2's tunes.

Last time I checked it (probably around mid-2023 or a bit later), it was obviously not just a matter of replacing the macro SOPWITH1_TUNE with a variable. I wasn't sure what would be the right approach in case the user changes the tune while it's already playing.

The original PC speaker timer chip runs at 1.19328 MHz, but the square wave in src/sdl/pcsound.c is sampled at 48 kHz. This leads to very noticeable aliasing artifacts (it's the DTMF-like sounds accompanying the square waves). This is not how it sounds on original hardware, and it's a bit unpleasant, so I think it's worth fixing.

For maximum accuracy, it should sample the square wave at 1.19328 MHz and then do downsampling to 48 kHz (that entails doing a 24 kHz low-pass filter on the 1.19328 MHz samples and then taking every nth sample at the right ratio -- it's roughly every 25th sample, and you can take averages of adjacent samples to deal with the non-integer ratio between the sampling rates).

However, for good-enough output without needing to do any of that math, instead it can oversample the square wave and take an average.

diff --git a/src/sdl/pcsound.c b/src/sdl/pcsound.c
index ee9180f..743779d 100644
--- a/src/sdl/pcsound.c
+++ b/src/sdl/pcsound.c
@@ -209,8 +209,13 @@ static void snd_callback(void *userdata, Uint8 *stream8, int len)
                if (!speaker_on) {
                        sample = 0;
                } else {
-                       sample = square_wave(current_freq * (i + lasttime)
-                                          / output_freq);
+                       // Sample the square wave at close to TIMER_FREQ and downsample using a simple low-pass filter.
+                       // This reduces aliasing artifacts.
+                       float presample = 0;
+                       for (int j = 0; j < 25; j++) {
+                               presample += square_wave(current_freq * (i + lasttime + j/25.0) / output_freq);
+                       }
+                       sample = presample / 25.0;
                }
                sample = FilterNext(&tinny_filter, sample);
                stream[i] = (signed int) (sample * VOLUME);

To my ears, 25 is overkill, and you can get away with 3.

Summary

When I saw the #IFDEF LCD preprocessor directive in video.c, I got interested in adding a color palette that similarly replicates my own original experience with Sopwith, except on an amber monochrome CGA monitor.

Idea

If it's not too big of a change, I'd like to promote that color palette option from preprocessor directive to full configuration option in the menu.

Example

I roughed together a quick example of what this feature could look like, by adding a new configuration option with a new type:

	{"conf_video_palette",	CONF_INT, {&conf_video_palette}},

(press the play button to see the colour palette change)

Questions

1. Would it be more in-line with the spirit of things to simply add my own preprocessor directive instead?
2. If added, is implementing a CONF_INT the best way to do it?
3. Since the configuration menu is filling up in terms of numbered options, would a submenu accessed using a letter be preferable? (Similar to how keybindings has its own submenu)

To make it easier for non-C people like me to mess around with it.

On macOS I ran

brew install SDL2
sh autogen.sh
make

and run it by double-clicking src/sopwith.

In novice mode you can't stall the plane, but because of this it's possible to stop the plane in mid-air if travelling slowly enough and the plane is tilted up at a steep angle. This bug doesn't exist in the Network/Author's Edition so must have been introduced at some point in SDL Sopwith's development

The current sound output is deafening and very hard on the ears because it's a square wave. So it's completely understandable that sound got disabled by default. But a better solution would be to apply a filter to make the sound less harsh - sounding like a real PC speaker would arguably be a more accurate representation of the original game anyway

We should save the window size and the display number so that the same window size gets used the next time the game runs.

Supposedly a feature of the original DOS versions (there are references to "history buffer", though I've never actually made it work). Besides being a nice feature, being able to record and play back demos could also useful for regression testing.

A nice "stretch goal" would be a mission recorder system with the ability to construct little gameplay videos (see Red Baron's mission recorder feature to understand what I mean)

I think Debian / Ubuntu have one already so maybe we can steal that?

Right now, the title music plays slower than the original matching DOS version.

This experimental change partially resolves the differences, but there may still be precision errors (especially right after starting the program):

diff --git a/src/swsound.c b/src/swsound.c
index 1da8869..d3d68b9 100644
--- a/src/swsound.c
+++ b/src/swsound.c
@@ -607,7 +607,7 @@ void swsndupdate(void)
        int thisclock = Timer_GetMS();
 
        if (thisclock > lastclock + 1000 / 18.2) {
-               lastclock = thisclock;
+               lastclock += 1000 / 18.2;
                soundadj();
        }
 }

See here:

After the first level, the game is made more difficult by having the ground targets shoot back at enemy planes. But the logic only targets the first plane on the level (player 1, the cyan player). This should instead be searching through the object list to find any enemy planes that are in range.

I've been thinking about the way that toggling the sound is handled. If there's interest, I'd like to explore making these changes:

1. Change the toggle sound key from "S" to Ctrl+S
   • This frees the S key to be assignable for gameplay in the key bindings without losing the ability to toggle sound
   • Sound can then be toggled during the main menu, where "S" currently selects single player mode
2. Save the sound setting in sopwith.cfg and add it to the options menu
3. When the game is launched with the -q "quiet" option it will also change the sound setting to off. (There could also be a new command-line argument to force sound on, if desired.)

See title. Bug since the DOS versions.

Apart from simplifying one line of code, this can also resolve a bug (missing sounds + unexpected clicks) when used with SDL 2.0.10. I originally tried running sdl-sopwith with this version, given that it's what you get from Ubuntu 20.04 LTS' repository.

This is probably the impacting SDL commit, which is in 2.0.12: libsdl-org/SDL@aef1ed4

Another commit to mention (albeit not for the bug found by me) is the following one from 2.0.22: libsdl-org/SDL@bf66720

These are the changes applied by me:

diff --git a/src/sdl/pcsound.c b/src/sdl/pcsound.c
index 12edde5..0dfef94 100644
--- a/src/sdl/pcsound.c
+++ b/src/sdl/pcsound.c
@@ -188,7 +188,7 @@ static void snd_callback(void *userdata, Uint8 *stream8, int len)
 {
        static int lasttime;
        static float lastfreq;
-       uint16_t *stream = (uint16_t *) stream8;
+       int16_t *stream = (int16_t *) stream8;
        float sample;
        int i;
 
@@ -213,7 +213,7 @@ static void snd_callback(void *userdata, Uint8 *stream8, int len)
                                           / output_freq);
                }
                sample = FilterNext(&tinny_filter, sample);
-               stream[i] = (1 << 15) + (signed int) (sample * VOLUME);
+               stream[i] = (int16_t) (sample * VOLUME);
        }
 
        lasttime += len;
@@ -307,7 +307,7 @@ void Speaker_Init(void)
 
        audiospec.samples = 1024;
        audiospec.freq = 48000;
-       audiospec.format = AUDIO_U16SYS;
+       audiospec.format = AUDIO_S16SYS;
        audiospec.channels = 1;
        audiospec.callback = &snd_callback;

I'd love to see scores uploaded to an online destination so that, upon loading the game, the reigning top scores are listed.