modules/spokes: add spokes module

This module started out as a way to test a line drawing algorithm, but
ended up looking interesting enough to include as a module of it's own.

 #ZephyrCommit #BirdwalkCommit

6 files changed, 370 insertions, 0 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index a2a8770..d2fe42b 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -62,6 +62,7 @@ libtil_la_LIBADD =						\
 			modules/snow/libsnow.la			\
 			modules/sparkler/libsparkler.la		\
 			modules/spiro/libspiro.la		\
+			modules/spokes/libspokes.la		\
 			modules/stars/libstars.la		\
 			modules/strobe/libstrobe.la		\
 			modules/stub/libstub.la			\
diff --git a/src/modules/Makefile.am b/src/modules/Makefile.am
index 6ce4786..825295d 100644
--- a/src/modules/Makefile.am
+++ b/src/modules/Makefile.am
@@ -26,6 +26,7 @@ SUBDIRS =			\
 		snow		\
 		sparkler	\
 		spiro		\
+		spokes		\
 		stars		\
 		strobe		\
 		stub		\
diff --git a/src/modules/spokes/Makefile.am b/src/modules/spokes/Makefile.am
new file mode 100644
index 0000000..099ba66
--- /dev/null
+++ b/src/modules/spokes/Makefile.am
@@ -0,0 +1,3 @@
+noinst_LTLIBRARIES = libspokes.la
+libspokes_la_SOURCES = draw.h spokes.c
+libspokes_la_CPPFLAGS = -I@top_srcdir@/src
diff --git a/src/modules/spokes/draw.h b/src/modules/spokes/draw.h
new file mode 100644
index 0000000..0b68c00
--- /dev/null
+++ b/src/modules/spokes/draw.h
@@ -0,0 +1,16 @@
+#ifndef _DRAW_H
+#define _DRAW_H
+
+#include <stdint.h>
+
+/* helper for scaling rgb colors and packing them into an pixel */
+static inline uint32_t makergb(uint32_t r, uint32_t g, uint32_t b, float intensity)
+{
+	r = (((float)intensity) * r);
+	g = (((float)intensity) * g);
+	b = (((float)intensity) * b);
+
+	return (((r & 0xff) << 16) | ((g & 0xff) << 8) | (b & 0xff));
+}
+
+#endif
diff --git a/src/modules/spokes/spokes.c b/src/modules/spokes/spokes.c
new file mode 100644
index 0000000..0aa8eed
--- /dev/null
+++ b/src/modules/spokes/spokes.c
@@ -0,0 +1,347 @@
+#include <math.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <time.h>
+#include <unistd.h>
+
+#include "til.h"
+#include "til_fb.h"
+#include "til_module_context.h"
+
+#include "draw.h"
+
+/* Copyright (C) 2022 Philip J. Freeman <elektron@halo.nu> */
+
+#define SPOKES_DEFAULT_ITERATIONS	3
+#define SPOKES_DEFAULT_TWIST		0.0625
+#define SPOKES_DEFAULT_THICKNESS	3
+
+typedef struct spokes_context_t {
+	til_module_context_t    til_module_context;
+	int			iterations;
+	float                   twist;
+	int			thickness;
+} spokes_context_t;
+
+typedef struct spokes_setup_t {
+	til_setup_t             til_setup;
+	int			iterations;
+	float                   twist;
+	int			thickness;
+} spokes_setup_t;
+
+static void spokes_draw_line(til_fb_fragment_t *fragment, int x1, int y1, int x2, int y2, uint32_t color, int thickness)
+{
+
+	int x, y, offset;
+
+	if(x1==x2 && y1==y2) {
+		til_fb_fragment_put_pixel_checked(fragment, TIL_FB_DRAW_FLAG_TEXTURABLE, x1, y1, color);
+		return;
+	}
+
+	int dx=x2-x1;
+	int dy=y2-y1;
+
+	if(abs(dx)>=abs(dy)) { /* iterate along x */
+		float rate=(float)dy/(float)dx;
+		if(dx>0) {
+			for(x=x1; x<=x2; x++) {
+				y=y1+round((x-x1)*rate);
+				if(y>=0 && y<fragment->height)
+					til_fb_fragment_put_pixel_checked(fragment, TIL_FB_DRAW_FLAG_TEXTURABLE, x, y, color);
+				for(offset=1; offset<thickness; offset++) {
+					if(y+offset<fragment->height)
+						til_fb_fragment_put_pixel_checked(fragment, TIL_FB_DRAW_FLAG_TEXTURABLE, x, y+offset, color);
+					if(y-offset>=0)
+						til_fb_fragment_put_pixel_checked(fragment, TIL_FB_DRAW_FLAG_TEXTURABLE, x, y-offset, color);
+				}
+			}
+		} else {
+			for(x=x1; x>=x2; x--) {
+				y=y1+round((x-x1)*rate);
+				if(y>=0 && y<fragment->height)
+					til_fb_fragment_put_pixel_checked(fragment, TIL_FB_DRAW_FLAG_TEXTURABLE, x, y, color);
+				for(offset=1; offset<thickness; offset++) {
+					if(y+offset<fragment->height)
+						til_fb_fragment_put_pixel_checked(fragment, TIL_FB_DRAW_FLAG_TEXTURABLE, x, y+offset, color);
+					if(y-offset>=0)
+						til_fb_fragment_put_pixel_checked(fragment, TIL_FB_DRAW_FLAG_TEXTURABLE, x, y-offset, color);
+				}
+			}
+		}
+
+	} else { /* iterate along y */
+		float rate=(float)dx/(float)dy;
+		if(dy>0) {
+			for(y=y1; y<=y2; y++) {
+				x=x1+round((y-y1)*rate);
+				if(x>=0 && x<fragment->width)
+					til_fb_fragment_put_pixel_checked(fragment, TIL_FB_DRAW_FLAG_TEXTURABLE, x, y, color);
+				for(offset=1; offset<thickness; offset++) {
+					if(x+offset<fragment->width)
+						til_fb_fragment_put_pixel_checked(fragment, TIL_FB_DRAW_FLAG_TEXTURABLE, x+offset, y, color);
+					if(x-offset>=0)
+						til_fb_fragment_put_pixel_checked(fragment, TIL_FB_DRAW_FLAG_TEXTURABLE, x-offset, y, color);
+				}
+			}
+		} else {
+			for(y=y1; y>=y2; y--) {
+				x=x1+round((y-y1)*rate);
+				if(x>=0 && x<fragment->width)
+					til_fb_fragment_put_pixel_checked(fragment, TIL_FB_DRAW_FLAG_TEXTURABLE, x, y, color);
+				for(offset=1; offset<thickness; offset++) {
+					if(x+offset<fragment->width)
+						til_fb_fragment_put_pixel_checked(fragment, TIL_FB_DRAW_FLAG_TEXTURABLE, x+offset, y, color);
+					if(x-offset>=0)
+						til_fb_fragment_put_pixel_checked(fragment, TIL_FB_DRAW_FLAG_TEXTURABLE, x-offset, y, color);
+				}
+			}
+		}
+	}
+}
+
+static void spokes_draw_segmented_line(til_fb_fragment_t *fragment, int iterations, double theta, int x1, int y1, int x2, int y2, uint32_t color, int thickness)
+{
+	/* recurse until iterations == 0 */
+
+	if(iterations>0) {
+		int midpoint_x=((x1+x2)/2);
+		int midpoint_y=((y1+y2)/2);
+
+		midpoint_x=cos(theta)*(midpoint_x-x1)-sin(theta)*(midpoint_y-y1)+x1;
+		midpoint_y=sin(theta)*(midpoint_x-x1)+cos(theta)*(midpoint_y-y1)+y1;
+
+		/* Check if any of the midpoints are outside of the drawable area and fix them. */
+		if (midpoint_x<0) midpoint_x=0;
+		if (midpoint_x>=fragment->width) midpoint_x=fragment->width-1;
+		if (midpoint_y<0) midpoint_y=0;
+		if (midpoint_y>=fragment->height) midpoint_y=fragment->height-1;
+
+		spokes_draw_segmented_line(fragment, iterations-1, theta*0.5, x1, y1, midpoint_x, midpoint_y, color, thickness);
+		spokes_draw_segmented_line(fragment, iterations-1, theta*-0.5, x2, y2, midpoint_x, midpoint_y, color, thickness);
+		return;
+	}
+	spokes_draw_line(fragment, x1, y1, x2, y2, color, thickness);
+}
+
+static void spokes_render_fragment(til_module_context_t *context, til_stream_t *stream, unsigned ticks, unsigned cpu, til_fb_fragment_t **fragment_ptr)
+{
+	til_fb_fragment_t       *fragment = *fragment_ptr;
+
+	int width = fragment->width, height = fragment->height;
+	int stride;
+	int offset;
+	uint32_t color;
+
+	int display_R, display_origin_x, display_origin_y;
+	int origin_x, origin_y;
+
+	spokes_context_t *ctxt = (spokes_context_t *)context;
+
+	/* calculate theta for twist */
+	double theta=M_PI*ctxt->twist;
+
+	/* Based on the fragment's dimensions, calculate the origin and radius of the largest
+	circle that can fully fit in the frame */
+
+	if(width>=height) {
+		display_R=(height-1)*0.5f;
+		display_origin_x=((width-height)*.5f)+display_R;
+		display_origin_y=display_R;
+	} else {
+		display_R=(width-1)*0.5f;
+		display_origin_x=display_R;
+		display_origin_y=((height-width)*.5f)+display_R;
+	}
+
+	/* calculate a moving origin for all the lines in this frame based on ticks */
+	origin_x=display_origin_x+cos((float)ticks*0.001)*display_R*0.7f;
+	origin_y=display_origin_y+sin((float)ticks*0.001)*display_R*0.7f;
+
+	/* calculate an offset for outer line endpoints based on ticks */
+	offset=(int)round((float)ticks*0.1); /* use the ticks. */
+
+	/* rotate through RGB color space slowly based on ticks */
+	color=makergb(
+		(int)round(255.0*sinf((float)ticks*0.00001)),
+		(int)round(255.0*sinf((float)ticks*0.00001+0.6667*M_PI)),
+		(int)round(255.0*sinf((float)ticks*0.00001+1.3333*M_PI)),
+		1);
+
+	/* find the largest even stride for the fragments dimensions */
+	stride=1;
+	for(int i=2; i<(width+height)/2; i++) {
+		if((width+height)%i==0) {
+			stride=i;
+		}
+	}
+
+	/* we're setup now to draw some shit */
+	til_fb_fragment_clear(fragment);
+
+	for(int i=0; i<=width+height-stride; i+=stride){ /* iterate over half the perimiter at a time... */
+		int perimiter_x=-1, perimiter_y=-1;
+		if(i+offset%stride<width) {
+			perimiter_x=i+offset%stride;
+			perimiter_y=0;
+		} else {
+			perimiter_x=width-1;
+			perimiter_y=(i-width)+offset%stride;
+		}
+
+		spokes_draw_segmented_line(fragment, ctxt->iterations, theta, origin_x, origin_y, perimiter_x, perimiter_y, color, ctxt->thickness);
+
+		/* Calculate and draw the mirror line... */
+		perimiter_x=abs(perimiter_x-width);
+		perimiter_y=abs(perimiter_y-height);
+		spokes_draw_segmented_line(fragment, ctxt->iterations, theta, origin_x, origin_y, perimiter_x, perimiter_y, color, ctxt->thickness);
+	}
+}
+
+
+static til_module_context_t * spokes_create_context(const til_module_t *module, til_stream_t *stream, unsigned seed, unsigned ticks, unsigned n_cpus, til_setup_t *setup)
+{
+	spokes_context_t *ctxt;
+
+	ctxt = til_module_context_new(module, sizeof(spokes_context_t), stream, seed, ticks, n_cpus, setup);
+	if (!ctxt)
+	        return NULL;
+	ctxt->iterations = ((spokes_setup_t *)setup)->iterations;
+	ctxt->twist = ((spokes_setup_t *)setup)->twist;
+	ctxt->thickness = ((spokes_setup_t *)setup)->thickness;
+	return &ctxt->til_module_context;
+
+}
+
+
+static void spokes_destroy_context(til_module_context_t *context)
+{
+	free(context);
+
+}
+
+
+int spokes_setup(const til_settings_t *settings, til_setting_t **res_setting, const til_setting_desc_t **res_desc, til_setup_t **res_setup);
+
+til_module_t	spokes_module = {
+	.create_context = spokes_create_context,
+	.destroy_context = spokes_destroy_context,
+	.render_fragment = spokes_render_fragment,
+	.setup = spokes_setup,
+	.name = "spokes",
+	.description = "Twisted spokes",
+	.author = "Philip J Freeman <elektron@halo.nu>",
+	.flags = TIL_MODULE_OVERLAYABLE,
+};
+
+
+int spokes_setup(const til_settings_t *settings, til_setting_t **res_setting, const til_setting_desc_t **res_desc, til_setup_t **res_setup)
+{
+	til_setting_t	*iterations;
+	const char	*iterations_values[] = {
+				"1",
+				"2",
+				"3",
+				"4",
+				NULL
+			};
+	til_setting_t	*twist;
+	const char	*twist_values[] = {
+				"-4.0",
+				"-2.0",
+				"-1.0",
+				"-0.5",
+				"-0.25",
+				"-0.125",
+				"-0.0625",
+				"-0.03125",
+				"-0.015125",
+				"0.0",
+				"0.015125",
+				"0.03125",
+				"0.0625",
+				"0.125",
+				"0.25",
+				"0.5",
+				"1.0",
+				"2.0",
+				"4.0",
+				NULL
+			};
+	til_setting_t	*thickness;
+	const char	*thickness_values[] = {
+				"1",
+				"2",
+				"3",
+				"5",
+				NULL
+			};
+	int r;
+
+	r = til_settings_get_and_describe_setting(settings,
+						&(til_setting_spec_t){
+							.name = "Iterations",
+							.key = "iterations",
+							.regex = "[0-9]+",
+							.preferred = TIL_SETTINGS_STR(SPOKES_DEFAULT_ITERATIONS),
+							.values = iterations_values,
+							.annotations = NULL
+						},
+						&iterations,
+						res_setting,
+						res_desc);
+	if (r)
+		return r;
+
+	r = til_settings_get_and_describe_setting(settings,
+						&(til_setting_spec_t){
+							.name = "Twist",
+							.key = "twist",
+							.regex = "[0-9]+\\.[0-9]+",
+							.preferred = TIL_SETTINGS_STR(SPOKES_DEFAULT_TWIST),
+							.values = twist_values,
+							.annotations = NULL
+						},
+						&twist,
+						res_setting,
+						res_desc);
+	if (r)
+		return r;
+
+	r = til_settings_get_and_describe_setting(settings,
+						&(til_setting_spec_t){
+							.name = "Thickness",
+							.key = "thickness",
+							.regex = "[0-9]+",
+							.preferred = TIL_SETTINGS_STR(SPOKES_DEFAULT_THICKNESS),
+							.values = thickness_values,
+							.annotations = NULL
+						},
+						&thickness,
+						res_setting,
+						res_desc);
+	if (r)
+		return r;
+
+	if (res_setup) {
+		spokes_setup_t	*setup;
+
+		setup = til_setup_new(settings,sizeof(*setup), NULL, &spokes_module);
+		if (!setup)
+			return -ENOMEM;
+
+		if (sscanf(iterations->value, "%i", &setup->iterations) != 1)
+			return til_setup_free_with_failed_setting_ret_err(&setup->til_setup, iterations, res_setting, -EINVAL);
+
+		if (sscanf(twist->value, "%f", &setup->twist) != 1)
+			return til_setup_free_with_failed_setting_ret_err(&setup->til_setup, twist, res_setting, -EINVAL);
+
+		if (sscanf(thickness->value, "%i", &setup->thickness) != 1)
+			return til_setup_free_with_failed_setting_ret_err(&setup->til_setup, thickness, res_setting, -EINVAL);
+
+		*res_setup = &setup->til_setup;
+	}
+
+	return 0;
+}
diff --git a/src/til.c b/src/til.c
index 18733d9..709aabb 100644
--- a/src/til.c
+++ b/src/til.c
@@ -53,6 +53,7 @@ extern til_module_t	shapes_module;
 extern til_module_t	signals_module;
 extern til_module_t	snow_module;
 extern til_module_t	sparkler_module;
+extern til_module_t	spokes_module;
 extern til_module_t	spiro_module;
 extern til_module_t	stars_module;
 extern til_module_t	strobe_module;
@@ -97,6 +98,7 @@ static const til_module_t	*modules[] = {
 	&snow_module,
 	&sparkler_module,
 	&spiro_module,
+	&spokes_module,
 	&stars_module,
 	&strobe_module,
 	&stub_module,