Method DrawFogOverlay

src/weather.cpp:322–353

}

void Weather::DrawFogOverlay(Bitmap& dst, const Bitmap& overlay) {
	const auto dr = dst.GetRect();
	constexpr auto sr = overlay_bitmap_rect;

	auto* src = ApplyToneEffect(overlay, sr);

	auto strength = Utils::Clamp(Main_Data::game_screen->GetWeatherStrength(), 0, num_opacities - 1);
	int back_opacity = fog_opacity[0][strength];
	int front_opacity = fog_opacity[1][strength];

	const auto shake_x = Main_Data::game_screen->GetShakeOffsetX();
	const auto shake_y = Main_Data::game_screen->GetShakeOffsetY();

	// RPG_RT uses the first 2 particles for fog layer graphics
	const auto& particles = Main_Data::game_screen->GetParticles();
	assert(particles.size() >= num_fog_particles);
	const auto fog_bg_frames = particles[0].x;
	const auto fog_fg_frames = particles[1].x;

	// Front layer moves left one pixel every 8 frames.
	const int fx = shake_x + (fog_fg_frames / 8) % sr.width;
	// Back layer moves left one pixel every 4 frames.
	const int bx = shake_x - (fog_bg_frames / 4) % sr.width;
	// Front layer moves vertically up and down using this algorithm. And it uses the background frame counter!
	// Confirmed to be matching RPG_RT
	const int fy = shake_y - Utils::RoundTo<int>(std::sin(fog_bg_frames * M_PI / 4096.0) * (sr.height / 2)) - (sr.height / 4);
	// Back layer never moves vertically
	const int by = shake_y;

	dst.TiledBlit(bx, by, sr, *src, dr, back_opacity);
	dst.TiledBlit(fx, fy, sr, *src, dr, front_opacity);
}

void Weather::SetTone(Tone tone) {
	if (tone != tone_effect) {