Smooth day-night transitions

1 files changed, 41 insertions, 15 deletions

diff --git a/src/daynightratio.h b/src/daynightratio.h
index 9b31ecddd..96c6729eb 100644
--- a/src/daynightratio.h
+++ b/src/daynightratio.h
@@ -20,23 +20,49 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #ifndef DAYNIGHTRATIO_HEADER
 #define DAYNIGHTRATIO_HEADER
 
-inline u32 time_to_daynight_ratio(u32 time_of_day)
+inline u32 time_to_daynight_ratio(float time_of_day, bool smooth)
 {
-	s32 t = time_of_day%24000;
-	if(t < 4500 || t >= 19500)
-		return 150;
-	else if(t < 4750 || t >= 19250)
-		return 250;
-	else if(t < 5000 || t >= 19000)
-		return 350;
-	else if(t < 5250 || t >= 18750)
-		return 500;
-	else if(t < 5500 || t >= 18500)
-		return 675;
-	else if(t < 5750 || t >= 18250)
-		return 875;
-	else
+	float t = time_of_day;
+	if(t < 0)
+		t += ((int)(-t)/24000)*24000;
+	if(t >= 24000)
+		t -= ((int)(t)/24000)*24000;
+	if(t > 12000)
+		t = 24000 - t;
+	float values[][2] = {
+		{4250+125, 150},
+		{4500+125, 150},
+		{4750+125, 250},
+		{5000+125, 350},
+		{5250+125, 500},
+		{5500+125, 675},
+		{5750+125, 875},
+		{6000+125, 1000},
+		{6250+125, 1000},
+	};
+	if(!smooth){
+		float lastt = values[0][0];
+		for(u32 i=1; i<sizeof(values)/sizeof(*values); i++){
+			float t0 = values[i][0];
+			float switch_t = (t0 + lastt) / 2;
+			lastt = t0;
+			if(switch_t <= t)
+				continue;
+			return values[i][1];
+		}
 		return 1000;
+	} else {
+		for(u32 i=0; i<sizeof(values)/sizeof(*values); i++){
+			if(values[i][0] <= t)
+				continue;
+			if(i == 0)
+				return values[i][1];
+			float td0 = values[i][0] - values[i-1][0];
+			float f = (t - values[i-1][0]) / td0;
+			return f * values[i][1] + (1.0 - f) * values[i-1][1];
+		}
+		return 1000;
+	}
 }
 
 #endif