From 446535d4d315b226416b8543765ca17d8078a22c Mon Sep 17 00:00:00 2001
From: P. J. McDermott <pjm@nac.net>
Date: Sat, 02 Mar 2013 22:05:45 -0500
Subject: src/main.c: Run morn->day->eve->night cycle.

---
diff --git a/src/main.c b/src/main.c
index 8caab89..7bfcdc2 100644
--- a/src/main.c
+++ b/src/main.c
@@ -7,6 +7,42 @@
 #include "viewport.h"
 #include "area.h"
 
+#define CYCLE_LINEAR(t_max, r1, g1, b1, r2, g2, b2)                            \
+	do {                                                                   \
+		x = (double) t / (double) t_max;                               \
+		y_end = (i % 8) * 36;                                          \
+		y_start = y_end * r1;                                          \
+		y_end = y_end * r2;                                            \
+		colors[i].r = x * (y_end - y_start) + y_start;                 \
+		y_end = (i % 64 / 8) * 36;                                     \
+		y_start = y_end * g1;                                          \
+		y_end = y_end * g2;                                            \
+		colors[i].g = x * (y_end - y_start) + y_start;                 \
+		y_end = (i / 64) * 85;                                         \
+		y_start = y_end * b1;                                          \
+		y_end = y_end * b2;                                            \
+		colors[i].b = x * (y_end - y_start) + y_start;                 \
+	} while (0)
+#define CYCLE_COS(t_max, r1, g1, b1, r2, g2, b2)                               \
+	do {                                                                   \
+		x = t * 3.14159 / t_max;                                       \
+		y_end = (i % 8) * 36;                                          \
+		y_start = y_end * r2;                                          \
+		y_end = y_end * r1;                                            \
+		colors[i].r = ((cos(x) + 1) / 2) *                             \
+			(y_end - y_start) + y_start;                           \
+		y_end = (i % 64 / 8) * 36;                                     \
+		y_start = y_end * g2;                                          \
+		y_end = y_end * g1;                                            \
+		colors[i].g = ((cos(x) + 1) / 2) *                             \
+			(y_end - y_start) + y_start;                           \
+		y_end = (i / 64) * 85;                                         \
+		y_start = y_end * b2;                                          \
+		y_end = y_end * b1;                                            \
+		colors[i].b = ((cos(x) + 1) / 2) *                             \
+			(y_end - y_start) + y_start;                           \
+	} while (0)
+
 #define DEMO()                                                                 \
 	do {                                                                   \
 		vp->x = x + map->tilewidth / 2 - vp->w / 2;                    \
@@ -59,47 +95,74 @@ main(void)
 
 	render_area_to_viewport(a, vp);
 	{
-		Uint32 t;
+		Uint32 d, t;
 		double x;
 		int y_start, y_end;
 
-		for (t = 0; t <= 2880; t += 5) {
-			for (i = 0; i < 256; ++i) {
-				/*
-				 * t => [0 .. INF]
-				 * t[0 .. 1440] => x[0, 3.14159]
-				 * x = (t % 1440) * 3.14159 / 720
-				 * y => [y_start, y_end]
-				 * ((cos(x) + 1) / 2) => [0,1]
-				 * y = ((cos(x) + 1) / 2) *
-				 *     (y_end - y_start) + y_start
-				 */
-
-				x = t % 1440;
-				x = x * 3.14159 / 720;
-
-				y_start = (i % 8) * 36;
-				y_end = y_start * 0.25;
-				colors[i].r = ((cos(x) + 1) / 2) *
-					(y_end - y_start) + y_start;
-
-				y_start = (i % 64 / 8) * 36;
-				y_end = y_start * 0.25;
-				colors[i].g = ((cos(x) + 1) / 2) *
-					(y_end - y_start) + y_start;
-
-				y_start = (i / 64) * 85;
-				y_end = y_start * 0.375;
-				colors[i].b = ((cos(x) + 1) / 2) *
-					(y_end - y_start) + y_start;
+		for (d = 0; d < 4; ++d) {
+			/* morn -> day */
+			for (t = 0; t < 360; t += 1) {
+				for (i = 0; i < 256; ++i) {
+					CYCLE_COS(360,
+							1.000, 0.875, 0.625,
+							1.000, 1.000, 1.000
+							);
+				}
+				if (!SDL_SetPalette(vp->screen, SDL_LOGPAL,
+							colors, 0, 256)) {
+					warn("Failed to set palette");
+				}
+				SDL_Flip(vp->screen);
+				SDL_Delay(10);
 			}
-			if (!SDL_SetPalette(vp->screen, SDL_LOGPAL, colors, 0, 256)) {
-				warn("Failed to set palette");
+			/* day -> eve */
+			for (t = 0; t < 360; t += 1) {
+				for (i = 0; i < 256; ++i) {
+					CYCLE_COS(360,
+							1.000, 1.000, 1.000,
+							0.875, 0.625, 0.625
+							);
+				}
+				if (!SDL_SetPalette(vp->screen, SDL_LOGPAL,
+							colors, 0, 256)) {
+					warn("Failed to set palette");
+				}
+				SDL_Flip(vp->screen);
+				SDL_Delay(10);
+			}
+			/* eve -> night */
+			for (t = 0; t < 360; t += 1) {
+				for (i = 0; i < 256; ++i) {
+					CYCLE_COS(360,
+							0.875, 0.625, 0.625,
+							0.250, 0.250, 0.500
+							);
+				}
+				if (!SDL_SetPalette(vp->screen, SDL_LOGPAL,
+							colors, 0, 256)) {
+					warn("Failed to set palette");
+				}
+				SDL_Flip(vp->screen);
+				SDL_Delay(10);
+			}
+			/* night -> morn */
+			for (t = 0; t < 360; t += 1) {
+				for (i = 0; i < 256; ++i) {
+					CYCLE_COS(360,
+							0.250, 0.250, 0.500,
+							1.000, 0.875, 0.625
+							);
+				}
+				if (!SDL_SetPalette(vp->screen, SDL_LOGPAL,
+							colors, 0, 256)) {
+					warn("Failed to set palette");
+				}
+				SDL_Flip(vp->screen);
+				SDL_Delay(10);
 			}
-			SDL_Flip(vp->screen);
-			SDL_Delay(10);
 		}
 	}
+	quit(0);
 
 	/* Demo */
 	for (i = 0; i < 256; ++i) {
--
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