stars: fix bugs, big refactor for resizing

- use a context not globals
- use floats and a "unit cube" to simulate the starfield

4 files changed, 122 insertions, 184 deletions

diff --git a/src/modules/stars/Makefile.am b/src/modules/stars/Makefile.am
index e72891e..20ee80e 100644
--- a/src/modules/stars/Makefile.am
+++ b/src/modules/stars/Makefile.am
@@ -1,3 +1,3 @@
 noinst_LIBRARIES = libstars.a
-libstars_a_SOURCES = draw.h stars.c starslib.c starslib.h
+libstars_a_SOURCES = draw.h stars.c
 libstars_a_CPPFLAGS = -I@top_srcdir@/src
diff --git a/src/modules/stars/stars.c b/src/modules/stars/stars.c
index 63ff73c..9c1de5b 100644
--- a/src/modules/stars/stars.c
+++ b/src/modules/stars/stars.c
@@ -5,56 +5,146 @@
 #include <time.h>
 #include <sys/types.h>
 #include <unistd.h>
+#include <math.h>
 
 #include "draw.h"
 #include "fb.h"
 #include "rototiller.h"
-#include "starslib.h"
 
-/* Copyright (C) 2017 Philip J. Freeman <elektron@halo.nu> */
+/* Copyright (C) 2017-19 Philip J. Freeman <elektron@halo.nu> */
 
-static void stars_render_fragment(void *context, unsigned cpu, fb_fragment_t *fragment)
+struct points
+{
+	float x, y, z;
+	struct points *next;
+};
+
+
+typedef struct stars_context_t {
+	struct		points* points;
+} stars_context_t;
+
+
+float get_random_unit_coord() {
+	return (((float)rand()/(float)RAND_MAX)*2.0)-1.0;
+}
+
+
+static void * stars_create_context(unsigned num_cpus)
 {
-	static int	initialized, z;
-	static struct	universe* u;
-
-	struct		return_point rp;
-	int		x, y, width = fragment->width, height = fragment->height;
-
-	if (!initialized) {
-		z = 128;
-		srand(time(NULL) + getpid());
-
-		// Initialize the stars lib (and pre-add a bunch of stars)
-		new_universe(&u, width, height, z);
-		for(y=0; y<z; y++) {
-			while (process_point(u, &rp) != 0);
-			for(x=0; x<rand()%128; x++){
-				new_point(u);
-			}
+	stars_context_t *ctxt;
+	float		z;
+	struct points* p_ptr = NULL;
+
+	ctxt = malloc(sizeof(stars_context_t));
+	if (!ctxt)
+		return NULL;
+
+	ctxt->points = NULL;
+
+	//add a bunch of points
+	for(z=0.01; z<1; z=z+0.01) {
+		for(int i=0; i<rand()%16; i++){
+			p_ptr = malloc(sizeof(struct points));
+			if (!p_ptr)
+				return NULL;
+			p_ptr->x = get_random_unit_coord();
+			p_ptr->y = get_random_unit_coord();
+			p_ptr->z = z;
+			p_ptr->next = ctxt->points;
+			ctxt->points = p_ptr;
 		}
-		initialized = 1;
 	}
+	return ctxt;
+}
+
+static void stars_destroy_context(void *context)
+{
+	stars_context_t *ctxt = context;
+	struct points* p_ptr;
+	struct points* last_ptr=NULL;
+
+	for ( p_ptr=ctxt->points; p_ptr != NULL; p_ptr = p_ptr->next)
+	{
+		if (last_ptr!=NULL)
+			free(last_ptr);
+
+		last_ptr=p_ptr;
+	}
+
+	free(last_ptr);
+
+	free(context);
+}
+
+
+static void stars_render_fragment(void *context, unsigned cpu, fb_fragment_t *fragment)
+{
+	stars_context_t	*ctxt = context;
+	struct points* iterator;
+	struct points* tmp_ptr;
+	struct points* last_ptr=NULL;
+	float		x, y, pos_x, pos_y, opacity;
+	int		width = fragment->width, height = fragment->height;
+
 
-	// draw space (or blank the frame, if you prefer)
 	fb_fragment_zero(fragment);
 
-	// draw stars
-	for (;;) {
-		int ret = process_point( u, &rp  );
-		if (ret==0) break;
-		if (ret==1) fb_fragment_put_pixel_unchecked(fragment, rp.x+(width/2), rp.y+(height/2),
-				       makergb(0xFF, 0xFF, 0xFF, (float)rp.opacity/OPACITY_MAX)
-				      );
+	iterator=ctxt->points;
+	for(;;)
+	{
+		if(iterator == NULL)
+			break;
+
+		if(iterator->z >= 1) {
+			if(last_ptr == NULL)
+				ctxt->points = iterator->next;
+			else
+				last_ptr->next = iterator->next;
+			tmp_ptr = iterator;
+			iterator = iterator->next;
+			free(tmp_ptr);
+			continue;
+		}
+
+		x = iterator->x / (1.f - iterator->z);
+		y = iterator->y / (1.f - iterator->z);
+
+		pos_x = ((x+1.f)*.5f)*(float)width;
+		pos_y = ((y+1.f)*.5f)*(float)height;
+
+		if (pos_x>0 && pos_x<width && pos_y >0 && pos_y < height) {
+			if(iterator->z<0.1)
+				opacity = iterator->z*10;
+			else
+				opacity = 1;
+
+			fb_fragment_put_pixel_unchecked(fragment, pos_x, pos_y,
+				makergb(0xFF, 0xFF, 0xFF, opacity));
+
+		}
+
+		iterator->z += 0.01;
+		last_ptr=iterator;
+		iterator=iterator->next;
 	}
 
 	// add stars at horizon
-	for (x=0; x<rand()%128; x++) {
-		new_point(u);
+	for(int i=0; i<rand()%16; i++){
+		tmp_ptr = malloc(sizeof(struct points));
+		if (!tmp_ptr)
+			break;
+		tmp_ptr->x = get_random_unit_coord();
+		tmp_ptr->y = get_random_unit_coord();
+		tmp_ptr->z = 0.01;
+		tmp_ptr->next = ctxt->points;
+		ctxt->points = tmp_ptr;
 	}
 }
 
 rototiller_module_t	stars_module = {
+	.create_context  = stars_create_context,
+	.destroy_context = stars_destroy_context,
 	.render_fragment = stars_render_fragment,
 	.name = "stars",
 	.description = "Basic starfield",
diff --git a/src/modules/stars/starslib.c b/src/modules/stars/starslib.c
deleted file mode 100644
index 9d43062..0000000
--- a/src/modules/stars/starslib.c
+++ /dev/null
@@ -1,133 +0,0 @@
-/*
- * 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; }
-			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);
-			}
-		}
-	}
-}
diff --git a/src/modules/stars/starslib.h b/src/modules/stars/starslib.h
deleted file mode 100644
index 0c125a3..0000000
--- a/src/modules/stars/starslib.h
+++ /dev/null
@@ -1,19 +0,0 @@
-struct universe
-{
-	int width, height, depth;
-	struct points* points;
-	struct points* iterator;
-};
-
-void new_universe( struct universe** u, int width, int height, int depth );
-void new_point( struct universe* universe );
-
-#define OPACITY_MAX 8
-struct return_point
-{
-	int x, y;
-	int opacity;
-};
-
-int process_point( struct universe *u, struct return_point *rp );
-