From c8b77543492c56b747394e2a460074febeaaeab5 Mon Sep 17 00:00:00 2001
From: Philip J Freeman <elektron@halo.nu>
Date: Mon, 9 Jan 2017 00:35:32 -0800
Subject: stars: add starfield simulator from ph1l/stars

---
 modules/stars/starslib.c | 133 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 133 insertions(+)
 create mode 100644 modules/stars/starslib.c

(limited to 'modules/stars/starslib.c')

diff --git a/modules/stars/starslib.c b/modules/stars/starslib.c
new file mode 100644
index 0000000..3c1905c
--- /dev/null
+++ b/modules/stars/starslib.c
@@ -0,0 +1,133 @@
+/*
+ * a starfield simulation library from: https://github.com/ph1l/stars
+ * Copyright 2014 Philip J. Freeman <elektron@halo.nu>
+ */
+
+#include <stdlib.h>
+#ifdef DEBUG
+#include <stdio.h>
+#endif
+#include "starslib.h"
+
+struct points
+{
+	int x, y, z;
+	struct points *next;
+};
+
+void new_universe( struct universe** u, int width, int height, int depth )
+{
+	*u = malloc(sizeof(struct universe));
+
+	(*u)->width  = width;
+	(*u)->height = height;
+	(*u)->depth  = depth;
+
+	(*u)->iterator  = NULL;
+	(*u)->points  = NULL;
+	#ifdef DEBUG
+	printf("NEW UNIVERSE: %lx: (%i,%i,%i)\n", (long unsigned int )(*u), (*u)->width, (*u)->height, (*u)->depth);
+	#endif
+
+	return;
+}
+
+void new_point( struct universe* u )
+{
+
+	struct points* p_ptr = malloc(sizeof(struct points));
+
+	p_ptr->x    = (rand()%u->width - (u->width/2)) * u->depth;
+	p_ptr->y    = (rand()%u->height - (u->height/2)) * u->depth;
+	p_ptr->z    = u->depth;
+
+	p_ptr->next = u->points;
+	u->points = p_ptr;
+	#ifdef DEBUG
+	printf("NEW POINT: %lx: (%i,%i,%i) next=%lx\n", (long unsigned int )p_ptr, p_ptr->x, p_ptr->y, p_ptr->z, (long unsigned int) p_ptr->next);
+	#endif
+
+	return;
+}
+
+void kill_point( struct universe* universe, struct points* to_kill )
+{
+
+	struct points *p_ptr, *last_ptr = NULL;
+
+
+	for ( p_ptr = universe->points; p_ptr != NULL; p_ptr = p_ptr->next)
+	{
+		if (p_ptr == to_kill)
+		{
+			#ifdef DEBUG
+			printf("KILL POINT: %lx: (%i,%i,%i).\n", (long unsigned int )p_ptr, p_ptr->x, p_ptr->y, p_ptr->z);
+			#endif
+			if (last_ptr == NULL)
+			{
+				universe->points = p_ptr->next;
+			} else {
+				last_ptr->next = p_ptr->next;
+			}
+			free(p_ptr);
+		} else {
+			last_ptr = p_ptr;
+		}
+	}
+	#ifdef DEBUG
+	printf("KILL POINT: %lx\n", (long unsigned int )p_ptr);
+	#endif
+	return;
+}
+
+int process_point( struct universe *u, struct return_point *rp )
+{
+
+	if ( u->iterator == NULL ) {
+		if (u->points == NULL){
+			return 0;
+		} else {
+			u->iterator = u->points;
+		}
+	}
+
+	if ( u->iterator->z == 0 ){
+		// Delete point that has reached us.
+		struct points *tmp = u->iterator;
+		u->iterator = u->iterator->next;
+		kill_point( u, tmp );
+		return(-1);
+	} else {
+		// Plot the point
+		int x, y;
+		x = u->iterator->x / u->iterator->z;
+		y = u->iterator->y / u->iterator->z;
+		if ( abs(x) >= u->width/2 || abs(y) >= u->height/2 ){
+			// Delete point that is off screen
+			struct points *tmp = u->iterator;
+			u->iterator = u->iterator->next;
+			kill_point( u, tmp );
+			if ( u->iterator == NULL ) {
+				return(0);
+			} else {
+				return(-1);
+			}
+		} else {
+			int m = OPACITY_MAX*((u->depth-u->iterator->z)*4)/u->depth;
+			if ( m>=OPACITY_MAX ){ m=OPACITY_MAX-1; }
+			u->iterator->z = u->iterator->z - 1;
+			#ifdef DEBUG
+			printf("RETURN POINT: %lx\n", (long unsigned int )u->iterator);
+			#endif
+			u->iterator = u->iterator->next;
+			rp->x = x;
+			rp->y = y;
+			rp->opacity = m;
+			if ( u->iterator == NULL ) {
+				return(0);
+			} else {
+				return(1);
+			}
+		}
+	}
+}
-- 
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