From 6286a3ed25cbc32e093b650a878f6e9e75ad13c0 Mon Sep 17 00:00:00 2001
From: Christian Kroll <chris@das-labor.org>
Date: Thu, 15 Dec 2011 04:43:40 +0000
Subject: [PATCH] integrated the black hole animation from the former borg
 simulator tree

---
 animations/Makefile    |  4 ++
 animations/blackhole.c | 99 ++++++++++++++++++++++++++++++++++++++++++
 animations/blackhole.h |  6 +++
 animations/config.in   |  1 +
 display_loop.c         |  7 +++
 5 files changed, 117 insertions(+)
 create mode 100644 animations/blackhole.c
 create mode 100644 animations/blackhole.h

diff --git a/animations/Makefile b/animations/Makefile
index b9d789a..8d4488c 100644
--- a/animations/Makefile
+++ b/animations/Makefile
@@ -61,6 +61,10 @@ ifneq (,$(filter y,$(ANIMATION_PLASMA) $(ANIMATION_PSYCHEDELIC)))
   SRC += fpmath_patterns.c
 endif
 
+ifeq ($(ANIMATION_BLACKHOLE),y)
+  SRC += blackhole.c
+endif
+
 ifeq ($(ANIMATION_TIME),y)
   SRC += borg_time.c
 endif
diff --git a/animations/blackhole.c b/animations/blackhole.c
new file mode 100644
index 0000000..aa293b4
--- /dev/null
+++ b/animations/blackhole.c
@@ -0,0 +1,99 @@
+#include <stdint.h>
+#include "../config.h"
+#include "../pixel.h"
+#include "../util.h"
+#include "../compat/pgmspace.h"
+#include "blackhole.h"
+
+// macro for simplifying flash memory access
+#define PGM(x) pgm_read_byte(&(x))
+
+
+/**
+ * Integer variant of the sinus function which takes an integer based angle
+ * (range from 0 to 63) where sin_i(64) corresponds to sin(2 * M_PI) * 64 and
+ * sin_i(16) corresponds to sin(0.5 * M_PI) * 64 (each excluding the fractional
+ * part). It uses a lookup table which models one quarter of a full sinus period
+ * and calculates the rest of the function from that quarter.
+ * @param angle angle based on an integer (range from 0 to 63)
+ * @return result of the sinus function normalized to a range from -64 to 64
+ */
+static signed char sin_i(unsigned char angle) {
+	// the aforementioned lookup table
+	static signed char const sinus_table[] PROGMEM =
+			{0, 6, 12, 19, 24, 30, 36, 41, 45, 49, 53, 56, 59, 61, 63, 64};
+
+	// determine correct index for the lookup table depending on the given angle
+	angle %= 64u;
+	unsigned char index;
+	if (angle < 16) {
+		index = angle;
+	} else if (angle < 32) {
+		index = 32 - angle;
+	} else if (angle < 48) {
+		index = angle - 32;
+	} else {
+		index = 64 - angle;
+	}
+
+	return (unsigned char)(PGM(sinus_table[index])) * (angle < 32 ? 1 : -1);
+}
+
+
+/**
+ * Integer variant of the cosinus function which takes an integer based angle
+ * (range from 0 to 63) where cos_i(64) corresponds to cos(2 * M_PI) * 64 and
+ * cos_i(16) corresponds to cos(0.5 * M_PI) * 64. It uses the sin_i function and
+ * shifts the given angle by 16 (which corresponds to 90 degrees).
+ * @param angle angle based on an integer (range from 0 to 63)
+ * @return result of the cosinus function normalized to a range from -64 to 64
+ */
+static signed char cos_i(unsigned char const angle) {
+	return sin_i(angle + 16);
+}
+
+
+#define NUM_CIRCLE 7
+
+
+/**
+ * Draws a black hole like pattern (viewed from different perspectives).
+ */
+void blackhole(void) {
+	pixel circlePoints[NUM_CIRCLE][8];
+	unsigned char add = 0;
+	signed char firstRadius = 80, helpRadius, angle = 0, x, y;
+	// initialize data
+	for (int k = 0; k < 800; k++) {
+		if (k > 300)
+			add = k / 16;
+		helpRadius = firstRadius;
+		for (unsigned char i = 0; i < NUM_CIRCLE; i++) {
+			for (unsigned char j = 0; j < 8; j++) {
+				if (j & 1) {
+					circlePoints[i][j].x = 64
+							+ (cos_i(angle + j * 8) * helpRadius) / 64;
+					circlePoints[i][j].y = 64
+							+ (sin_i(angle + add + j * 8) * helpRadius) / 64;
+
+				} else {
+					circlePoints[i][j].x = 64 +
+							(cos_i(angle + j * 8 + 4) * helpRadius) / 64;
+					circlePoints[i][j].y = 64 +
+							(sin_i(angle + add + j * 8 + 4) * helpRadius) / 64;
+				}
+				x = circlePoints[i][j].x / 8;
+				y = circlePoints[i][j].y / 8;
+				if (x < 16 && y < 16)
+					setpixel((pixel){x, y}, 3);
+			}
+			helpRadius = (helpRadius * 2) / 3;
+		}
+		wait(30);
+		clear_screen(0);
+		angle++;
+		firstRadius += 2;
+		if (firstRadius > 119)
+			firstRadius = 80;
+	}
+}
diff --git a/animations/blackhole.h b/animations/blackhole.h
new file mode 100644
index 0000000..bb8c416
--- /dev/null
+++ b/animations/blackhole.h
@@ -0,0 +1,6 @@
+#ifndef BLACKHOLE_H_
+#define BLACKHOLE_H_
+
+void blackhole(void);
+
+#endif /* BLACKHOLE_H_ */
diff --git a/animations/config.in b/animations/config.in
index df35351..cab52d8 100644
--- a/animations/config.in
+++ b/animations/config.in
@@ -58,6 +58,7 @@ comment "Animations"
 
 	bool "Plasma"            ANIMATION_PLASMA
 	bool "Psychedelic"       ANIMATION_PSYCHEDELIC
+	bool "Black Hole"        ANIMATION_BLACKHOLE
 
 	comment  "Special Animations"
 	bool     "Test Animations"  ANIMATION_TESTS
diff --git a/display_loop.c b/display_loop.c
index ec39888..1aca977 100644
--- a/display_loop.c
+++ b/display_loop.c
@@ -18,6 +18,7 @@
 #include "animations/28c3.h"
 #include "animations/fpmath_patterns.h"
 #include "animations/mherweg.h"
+#include "animations/blackhole.h"
 #ifdef ANIMATION_TIME
 #include "animations/borg_time.h"
 #endif
@@ -226,6 +227,11 @@ void display_loop(){
 			break;
 #endif
 
+#ifdef ANIMATION_BLACKHOLE
+		case 23:
+			blackhole();
+			break;
+#endif
 
 #ifdef ANIMATION_TESTS
 		case 31:
@@ -276,6 +282,7 @@ void display_loop(){
 		case 43:
 			menu();
 			mode = oldOldmode;
+			break;
 #else
 
 		case 42: