iw6-mod/src/client/component/demo_timescale.cpp
Caball c3a7f63336 Added demo code.
Includes client and server recording code, and playback code.
2024-12-31 00:45:51 +01:00

140 lines
4.2 KiB
C++

#include "std_include.hpp"
#include "loader/component_loader.hpp"
#include "demo_playback.hpp"
#include "fps.hpp"
#include "game/game.hpp"
#include "utils/hook.hpp"
#include "utils/string.hpp"
namespace demo_timescale
{
namespace
{
utils::hook::detour Com_TimeScaleMsec_hook;
game::dvar_t* demo_timescale;
void generate_pattern(std::array<std::uint8_t, 1000>& pattern, std::size_t ones_count, std::size_t zeros_count)
{
assert(ones_count + zeros_count == pattern.size());
for (std::size_t i = 0, zeros = 1, ones = 1; i < pattern.size(); ++i)
{
if (ones * zeros_count < zeros * ones_count)
{
++ones;
pattern[i] = 1;
}
else
{
++zeros;
pattern[i] = 0;
}
}
assert(std::accumulate(pattern.begin(), pattern.end(), 0) > 0);
}
void calculate_pattern(std::array<std::uint8_t, 1000>& pattern, float fps, float timescale)
{
// Com_TimeScaleMsec is called once per frame, so the number of calls it takes to advance 1000 ms
// can be calculated by using the following formula: fps / timescale
// example: 500 fps and 0.01 timescale -> 500 / 0.01 = 50'000
// a pattern needs to be generated where 1000 * 1ms and 49'000 * 0ms are interleaved,
// and fit in an array of size 1000
const auto call_count_per_sec = static_cast<std::size_t>(std::clamp(fps / timescale, 1000.0f, 1'000'000.0f));
const auto ones_count = static_cast<std::size_t>(pattern.size() / (call_count_per_sec / static_cast<float>(pattern.size())));
const auto zeros_count = pattern.size() - ones_count;
generate_pattern(pattern, ones_count, zeros_count);
}
std::int32_t Com_TimeScaleMsec_stub(std::int32_t msec)
{
if (!demo_playback::playing() || !demo_timescale || demo_timescale->current.value == 1.0f)
{
return Com_TimeScaleMsec_hook.invoke<std::int32_t>(msec);
}
if (demo_timescale->current.value == 0.0f)
{
return 0; // pause game
}
// the code below generates a pattern of interleaved 0s and 1s based on calculated avg fps
// a new pattern is generated every 1000 frames, or after timescale or maxfps changes
// the pattern determines the speed at which the game advances
const auto timescale = demo_timescale->current.value;
const auto avg_fps = fps::get_avg_fps();
const auto frame_time = timescale * 1000.0f / avg_fps;
const auto* com_maxfps = game::Dvar_FindVar("com_maxfps");
const auto maxfps = (com_maxfps) ? com_maxfps->current.integer : static_cast<std::int32_t>(avg_fps);
static auto last_timescale = timescale;
static auto last_maxfps = maxfps;
static std::size_t pattern_index;
static std::array<std::uint8_t, 1000> pattern;
if (last_timescale != timescale || last_maxfps != maxfps)
{
last_timescale = timescale;
last_maxfps = maxfps;
// update pattern using the maxfps instead of avg fps for now
calculate_pattern(pattern, static_cast<float>(maxfps), timescale);
// update the pattern again in the near future when the average fps is more accurate
pattern_index = 95 * pattern.size() / 100;
}
if (frame_time > 1.0f)
{
const auto i_frame_time = static_cast<std::int32_t>(frame_time);
const auto ones_count = static_cast<std::size_t>(frame_time * 1000 - i_frame_time * 1000);
if (ones_count <= 1)
{
return i_frame_time;
}
if (pattern_index % pattern.size() == 0)
{
const auto zeros_count = pattern.size() - ones_count;
generate_pattern(pattern, ones_count, zeros_count);
}
return i_frame_time + pattern[pattern_index++ % pattern.size()];
}
else if (pattern_index % pattern.size() == 0)
{
calculate_pattern(pattern, avg_fps, timescale);
}
// advance (1ms) or pause (0ms) based on the pattern
return pattern[pattern_index++ % pattern.size()];
}
}
class component final : public component_interface
{
public:
void post_unpack() override
{
if (!game::environment::is_mp())
{
return;
}
// add timescale support for demo playback
Com_TimeScaleMsec_hook.create(game::Com_TimeScaleMsec, Com_TimeScaleMsec_stub);
demo_timescale = game::Dvar_RegisterFloat(
"demotimescale", 1.0f, 0.0f, 1000.0f, game::DVAR_FLAG_NONE, "Set playback speed for demos");
}
};
}
REGISTER_COMPONENT(demo_timescale::component)