/* fade.c   by Michael Thorpe   2018-12-04 */
/* This file gets #include'd into scenes.c so we have those definitions */

#include <assert.h>
#include <sys/time.h>

static double fadestart;
static double fadefrac;
static int fadetoscenenum;
extern struct look fadelook; /* C stupidly disallows extern static */
static struct dmx fadetmpdmx={len:DMX_MAXCHAN};
static struct look fadetmp={name:".fadetmp",func:storedlook,dmx:&fadetmpdmx};
static struct look *fademode=0;

static void fade_setup(int newscenenum) {
	int i;
/* If we're already fading, make a copy of where we are and fade from there. */
	if(&fadelook==curlook) {
/* FIXME: This still doesn't work if we're triple-fading */
		fadetmpdmx.len=DMX_MAXCHAN;
		for(i=1;i<=fadetmpdmx.len;i++)
			fadetmpdmx.data[i]=fadelook.func(&fadelook,i);
		fadelook.subs[0]=&fadetmp;
	} else {
		fadelook.subs[0]=curlook;
	}
	fadelook.subs[1]=scenes[newscenenum].look;
	fadestart=gettime();
	fadefrac=0;
	fadetoscenenum=newscenenum;
	curlook=&fadelook;
}

static void fade_update(struct look *me,double now) {
	double sofar=now-fadestart;
	if(sofar<0)
		sofar=0;
	fadefrac=sofar/scenes[fadetoscenenum].fadetime;
	if(fadefrac>1.) /* we're still fading */
		fadefrac=1.;
	if(scenes[fadetoscenenum].fadetime+scenes[fadetoscenenum].followtime<=sofar) {
		curlook=fadelook.subs[1];
		if(scenes[fadetoscenenum].followtime) {
			startscene(fadetoscenenum+1);
			scenes_redraw();
		}
	}
}

static unsigned char fade_get(struct look *me,int chan) {
	unsigned char ca,cb;
	double da,db;
/* the "fademode" look supports per-channel fade modes defined as follows:
 *	0=LINEAR // linear ramp from prev to next
 *	1=IMMEDIATE // jump to next immediately
 *	2=MIDFADE // stay on prev until halfway through fade then jump to next
 *	3=ENDOFFADE // stay on prev until fade is done
 *	4=HTP // pick max of prev and next
 *	5=ZERO // output 0 during fade if prev and next don't match
 *	6=COARSE // this is MSB of 16-bit value, next channel is LSB
 *	7=FINE // this is LSB of 16-bit value, prev channel is MSB
*/
	switch((fademode && chan<=fademode->dmx->len)?fademode->dmx->data[chan]:0) {
	case 0: /* LINEAR */
	default:
		db=fadelook.subs[1]->func(fadelook.subs[1],chan);
		if(1. != fadefrac) {
			da=fadelook.subs[0]->func(fadelook.subs[0],chan);
			db=fadefrac*db + (1-fadefrac)*da;
		}
		if(db<0.)
			db=0.;
		if(255.<db)
			db=255.;
		return(db+.5);
	case 1: /* IMMEDIATE */
		return(fadelook.subs[1]->func(fadelook.subs[1],chan));
	case 2: /* MIDFADE */
		if(fadefrac<.5)
			return(fadelook.subs[0]->func(fadelook.subs[0],chan));
		return(fadelook.subs[1]->func(fadelook.subs[1],chan));
	case 3: /* ENDOFFADE */
		return(fadelook.subs[0]->func(fadelook.subs[0],chan));
	case 4: /* HTP */
		ca=fadelook.subs[0]->func(fadelook.subs[0],chan);
		cb=fadelook.subs[1]->func(fadelook.subs[1],chan);
		if(ca<cb)
			return(cb);
		return(ca);
	case 5: /* ZERO */
		return(0);
	case 6: /* MSB */
		db=fadelook.subs[1]->func(fadelook.subs[1],chan);
		db*=256;
		db+=fadelook.subs[1]->func(fadelook.subs[1],chan+1);
		if(1. != fadefrac) {
			da=fadelook.subs[0]->func(fadelook.subs[0],chan);
			da*=256;
			da+=fadelook.subs[0]->func(fadelook.subs[0],chan+1);
			db=fadefrac*db + (1-fadefrac)*da;
		}
		if(db<0.)
			db=0.;
		if(65535.<db)
			db=65535.;
		return((int)(db+.5)>>8);
	case 7: /* LSB */
		db=(1<chan)?fadelook.subs[1]->func(fadelook.subs[1],chan-1):0;
		db*=256;
		db+=fadelook.subs[1]->func(fadelook.subs[1],chan);
		if(1. != fadefrac) {
			da=(1<chan)?fadelook.subs[0]->func(fadelook.subs[0],chan-1):0;
			da*=256;
			da+=fadelook.subs[0]->func(fadelook.subs[0],chan);
			db=fadefrac*db + (1-fadefrac)*da;
		}
		if(db<0.)
			db=0.;
		if(65535.<db)
			db=65535.;
		return((int)(db+.5)&255);
	}
}

int fade_init() {
	fademode=findlook("fademode");
	return(0);
}

static struct look *fadelooks[2]={0,0};
struct look fadelook={name:".fade",func:fade_get,update:fade_update,subs:fadelooks,numsubs:2};