// draw.c

void draw_frame(SDL_Window *w, SDL_Renderer *r, Ampler_state *state) {
	SDL_SetRenderDrawColor(r, 0x1D, 0x2B, 0x53, 255);

	SDL_SetRenderDrawBlendMode(r, SDL_BLENDMODE_BLEND);
	SDL_SetRenderDrawBlendMode(r, SDL_BLENDMODE_NONE);
	SDL_SetRenderDrawColor(r, 10, 10, 10, 40);
	SDL_Rect screen = { 0, 0, 512, 512 };
	SDL_RenderFillRect(r, &screen);
	// SDL_RenderClear(r);

	// TODO: DRAW WITH X SCALE FACTOR
	// TODO: DRAW SMOLER
	SDL_SetRenderDrawColor(r, 0xFF, 0x00, 0x4D, 255);
	const space = (44100 * 8) / 512;
	const int t = 0; // TODO: DRAW L / R OVERLAPPED IN DIFF COLORS ?
	const int wav_h = 128;
	if 0 do
	foreach_ptr(Sound_src, snd, state -> sounds)
		if snd -> state != SND_FREE do {
			const int y = wav_h / 2 + (wav_h + 4) * snd_i;
			const int top = y - 64, bot = y + 64;
			for int x = 0; x < 512 and x * space < snd->track_len; x += 1 do {
				const int val = snd -> tracks[t][x * space];
				const int sign = val < 0 ? -1 : 1;
				SDL_RenderDrawLine(r, x, y + sign, x, y + val / 2);
				//SDL_RenderDrawPoint(r, x, y + val / 2);
			}

			const int x = snd -> pos / space;
			if state -> played_audio_last_frame do
				SDL_RenderDrawLine(r, x, top, x, bot);
			SDL_RenderDrawLine(r, snd->start / space, top, snd->start / space, bot);
			SDL_RenderDrawLine(r, snd->end / space, top, snd->end / space, bot);
		}

	static u8 markov[256][256];
	SDL_memset(markov, 0, sizeof markov);
	for int x = 0; x < FRAME_SAMPLES - 1; x += 1 do {
		u8 cur = state->frame_mix[0][x] + 128;
		u8 next = state->frame_mix[0][x + 1] + 128;
		markov[cur][next] += 1;
	}

	/*
	for int x = 0; x < 256; x += 1 do {
		u8 to = 0;
		for int y = 0; y < 255; y += 1 do to += markov[x][y];
		markov[x][255] = to;
	}
	*/

	int start_x = 255, end_x = 0;

	for int x = 0; x < 256; x += 1 do {
		// for each colum
		// copy into temp col, store how filed, col is
		// go over each thing, fill coll in Idx number of times
		// for remainder of col fill with re-roll value
		u8 temp[256] = { 0 }; // amount of each dest, by index
		for int i = 0; i < 256; i++
			do temp[i] = markov[x][i];
		s32 next = 0;
		for int i = 0; i < 256; i++ do
			for int j = 0; j < temp[i] and next < 256; j++ do {
				markov[x][next++] = i;
				if x < start_x do start_x = x;
				if x > end_x do end_x = x;
			}
	}

	//for int x = 0; x < 256; x++ do markov[x][0] = x, markov[0][x] = x;

	for int x = start_x; x < end_x; x += 1 do	
		for int y = 0; y < 256; y += 1 do {
			s32 m = markov[x][255 - y];
			SDL_SetRenderDrawColor(r,
				m >= 10 ? m : 0,
				MIN(255, m < 4 ? m * 100 : 0),
				MIN(255, m < 10 and m >= 4 ? m * 100 : 0), 255);
			if m != 0 do {
				SDL_RenderDrawPoint(r, x * 2, y * 2);
				SDL_RenderDrawPoint(r, x * 2 + 1, y * 2);
				SDL_RenderDrawPoint(r, x * 2, y * 2 + 1);
				SDL_RenderDrawPoint(r, x * 2 + 1, y * 2 + 1);
			}
		}

	SDL_RenderPresent(r);
}