stars: mess with the starfield

This commit adds some fun features to the starfield:

 - normalize aspect ratio to fragment size
 - rolling viewport
 - rotating viewport (with rate option)

1 files changed, 88 insertions, 10 deletions

diff --git a/src/modules/stars/stars.c b/src/modules/stars/stars.c
index bf7678a..df5dc3a 100644
--- a/src/modules/stars/stars.c
+++ b/src/modules/stars/stars.c
@@ -10,8 +10,13 @@
 #include "draw.h"
 #include "fb.h"
 #include "rototiller.h"
+#include "settings.h"
 
-/* Copyright (C) 2017-19 Philip J. Freeman <elektron@halo.nu> */
+/* Copyright (C) 2017-20 Philip J. Freeman <elektron@halo.nu> */
+
+#define DEFAULT_ROT_ADJ	.00003f
+
+static float	stars_rot_adj = DEFAULT_ROT_ADJ;
 
 struct points
 {
@@ -19,9 +24,14 @@ struct points
 	struct points *next;
 };
 
-
 typedef struct stars_context_t {
 	struct		points* points;
+	float		rot_adj;
+	float		rot_rate;
+	float		rot_angle;
+	float		offset_x;
+	float		offset_y;
+	float		offset_angle;
 } stars_context_t;
 
 
@@ -41,6 +51,12 @@ static void * stars_create_context(unsigned num_cpus)
 		return NULL;
 
 	ctxt->points = NULL;
+	ctxt->rot_adj = stars_rot_adj;
+	ctxt->rot_rate = 0.00;
+	ctxt->rot_angle = 0;
+	ctxt->offset_x = 0.5;
+	ctxt->offset_y = 0;
+	ctxt->offset_angle = 0.01;
 
 	//add a bunch of points
 	for(z=0.01; z<1; z=z+0.01) {
@@ -84,11 +100,18 @@ static void stars_render_fragment(void *context, unsigned cpu, fb_fragment_t *fr
 	struct points* iterator;
 	struct points* tmp_ptr;
 	struct points* last_ptr=NULL;
-	float		x, y, pos_x, pos_y, opacity;
+	float		x, y, pos_x, pos_y, rot_x, rot_y, opacity, x_mult, y_mult, max_radius;
 	int		width = fragment->width, height = fragment->height;
 
+	if(width>height) {
+		x_mult=1.f;
+		y_mult=(float)width/(float)height;
+	} else {
+		x_mult=(float)height/(float)width;
+		y_mult=1.f;
+	}
 
-	float max_radius=1.f+((width+height)*.001f);
+	max_radius=1.f+((width+height)*.001f);
 
 	fb_fragment_zero(fragment);
 
@@ -109,11 +132,14 @@ static void stars_render_fragment(void *context, unsigned cpu, fb_fragment_t *fr
 			continue;
 		}
 
-		x = iterator->x / (1.f - iterator->z);
-		y = iterator->y / (1.f - iterator->z);
+		x = (iterator->x / (1.f - iterator->z))*x_mult;
+		y = (iterator->y / (1.f - iterator->z))*y_mult;
+
+		rot_x = (x*cosf(ctxt->rot_angle))-(y*sinf(ctxt->rot_angle));
+		rot_y = (x*sinf(ctxt->rot_angle))+(y*cosf(ctxt->rot_angle));
 
-		pos_x = ((x+1.f)*.5f)*(float)width;
-		pos_y = ((y+1.f)*.5f)*(float)height;
+		pos_x = ((rot_x+ctxt->offset_x+1.f)*.5f)*(float)width;
+		pos_y = ((rot_y+ctxt->offset_y+1.f)*.5f)*(float)height;
 
 		if(iterator->z<0.1)
 			opacity = iterator->z*10;
@@ -124,8 +150,8 @@ static void stars_render_fragment(void *context, unsigned cpu, fb_fragment_t *fr
 			fb_fragment_put_pixel_unchecked(fragment, pos_x, pos_y,
 				makergb(0xFF, 0xFF, 0xFF, opacity));
 
-		for(int my_y=floorf(pos_y-max_radius); my_y<=ceilf(pos_y+max_radius); my_y++)
-		for(int my_x=floorf(pos_x-max_radius); my_x<=ceilf(pos_x+max_radius); my_x++) {
+		for(int my_y=floorf(pos_y-max_radius); my_y<=(int)ceilf(pos_y+max_radius); my_y++)
+		for(int my_x=floorf(pos_x-max_radius); my_x<=(int)ceilf(pos_x+max_radius); my_x++) {
 
 			//Is the point within our viewing window?
 			if (!(my_x>0 && my_x<width && my_y>0 && my_y<height))
@@ -157,12 +183,64 @@ static void stars_render_fragment(void *context, unsigned cpu, fb_fragment_t *fr
 		tmp_ptr->next = ctxt->points;
 		ctxt->points = tmp_ptr;
 	}
+
+	// handle rotation parameters
+	if(ctxt->rot_angle>M_PI_4)
+		ctxt->rot_rate=ctxt->rot_rate-ctxt->rot_adj;
+	else
+		ctxt->rot_rate=ctxt->rot_rate+ctxt->rot_adj;
+	ctxt->rot_angle=ctxt->rot_angle+ctxt->rot_rate;
+
+	// handle offset parameters
+	float tmp_x = (ctxt->offset_x*cosf(ctxt->offset_angle))-
+			(ctxt->offset_y*sinf(ctxt->offset_angle));
+	float tmp_y = (ctxt->offset_x*sinf(ctxt->offset_angle))+
+			(ctxt->offset_y*cosf(ctxt->offset_angle));
+	ctxt->offset_x = tmp_x;
+	ctxt->offset_y = tmp_y;
+}
+
+int stars_setup(const settings_t *settings, setting_desc_t **next_setting)
+{
+	const char	*rot_adj;
+	const char      *rot_adj_values[] = {
+				".0f",
+				".00001f",
+				".00003f",
+				".0001f",
+				".0003f",
+				".001f",
+				NULL
+			};
+
+	rot_adj = settings_get_value(settings, "rot_adj");
+	if(!rot_adj) {
+		int ret_val;
+
+		ret_val = setting_desc_clone(&(setting_desc_t){
+							.name = "Rotation Rate",
+							.key = "rot_adj",
+							.regex = "\\.[0-9]+",
+							.preferred = SETTINGS_STR(DEFAULT_ROT_ADJ),
+							.values = rot_adj_values,
+							.annotations = NULL
+						}, next_setting);
+		if(ret_val<0)
+			return ret_val;
+
+		return 1;
+	}
+
+	sscanf(rot_adj, "%f", &stars_rot_adj);
+
+	return 0;
 }
 
 rototiller_module_t	stars_module = {
 	.create_context  = stars_create_context,
 	.destroy_context = stars_destroy_context,
 	.render_fragment = stars_render_fragment,
+	.setup = stars_setup,
 	.name = "stars",
 	.description = "Basic starfield",
 	.author = "Philip J Freeman <elektron@halo.nu>",