modules/checkers: experimenting with a checkers overlay

This adds a checkers style overlay module, it's not terribly
interesting but may be made more useful if modules start
differentiating themselves as substantial vs. overlay effects.

It'd be nice if rtv/compose could automagically apply and
randomize overlay modules atop others, which would make use of
this type of thing as well as encourage more small modules like
these be written.

2 files changed, 305 insertions, 0 deletions

diff --git a/src/modules/checkers/Makefile.am b/src/modules/checkers/Makefile.am
new file mode 100644
index 0000000..817e88f
--- /dev/null
+++ b/src/modules/checkers/Makefile.am
@@ -0,0 +1,3 @@
+noinst_LTLIBRARIES = libcheckers.la
+libcheckers_la_SOURCES = checkers.c
+libcheckers_la_CPPFLAGS = -I@top_srcdir@/src
diff --git a/src/modules/checkers/checkers.c b/src/modules/checkers/checkers.c
new file mode 100644
index 0000000..a88f17c
--- /dev/null
+++ b/src/modules/checkers/checkers.c
@@ -0,0 +1,302 @@
+/*
+ *  Copyright (C) 2022 - Vito Caputo - <vcaputo@pengaru.com>
+ *
+ *  This program is free software: you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License version 2 as published
+ *  by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <errno.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "til.h"
+#include "til_fb.h"
+
+
+#define CHECKERS_DEFAULT_SIZE		32
+#define CHECKERS_DEFAULT_PATTERN	CHECKERS_PATTERN_CHECKERED
+#define CHECKERS_DEFAULT_DYNAMICS	CHECKERS_DYNAMICS_ODD
+#define CHECKERS_DEFAULT_DYNAMICS_RATE	1.0
+
+
+typedef enum checkers_pattern_t {
+	CHECKERS_PATTERN_CHECKERED,
+	CHECKERS_PATTERN_RANDOM,
+} checkers_pattern_t;
+
+typedef enum checkers_dynamics_t {
+	CHECKERS_DYNAMICS_ODD,
+	CHECKERS_DYNAMICS_EVEN,
+	CHECKERS_DYNAMICS_ALTERNATING,
+	CHECKERS_DYNAMICS_RANDOM,
+} checkers_dynamics_t;
+
+typedef struct checkers_setup_t {
+	unsigned		size;
+	checkers_pattern_t	pattern;
+	checkers_dynamics_t	dynamics;
+	float			rate;
+} checkers_setup_t;
+
+typedef struct checkers_context_t {
+	checkers_setup_t	setup;
+} checkers_context_t;
+
+
+static checkers_setup_t checkers_default_setup = {
+	.size = CHECKERS_DEFAULT_SIZE,
+	.pattern = CHECKERS_DEFAULT_PATTERN,
+	.dynamics = CHECKERS_DEFAULT_DYNAMICS,
+	.rate = CHECKERS_DEFAULT_DYNAMICS_RATE,
+};
+
+
+static void * checkers_create_context(unsigned ticks, unsigned num_cpus, void *setup)
+{
+	checkers_context_t	*ctxt;
+
+	if (!setup)
+		setup = &checkers_default_setup;
+
+	ctxt = calloc(1, sizeof(checkers_context_t));
+	if (!ctxt)
+		return NULL;
+
+	ctxt->setup = *(checkers_setup_t *)setup;
+
+	return ctxt;
+}
+
+
+static void checkers_destroy_context(void *context)
+{
+	free(context);
+}
+
+
+static int checkers_fragmenter(void *context, const til_fb_fragment_t *fragment, unsigned number, til_fb_fragment_t *res_fragment)
+{
+	checkers_context_t	*ctxt = context;
+
+	return til_fb_fragment_tile_single(fragment, ctxt->setup.size, number, res_fragment);
+}
+
+
+static void checkers_prepare_frame(void *context, unsigned ticks, unsigned n_cpus, til_fb_fragment_t *fragment, til_fragmenter_t *res_fragmenter)
+{
+	*res_fragmenter = checkers_fragmenter;
+}
+
+
+static inline unsigned hash(unsigned x)
+{
+	x = ((x >> 16) ^ x) * 0x61C88647;
+	x = ((x >> 16) ^ x) * 0x61C88647;
+	x = ((x >> 16) ^ x) * 0x61C88647;
+	x = (x >> 16) ^ x;
+
+	return x;
+}
+
+
+static void checkers_render_fragment(void *context, unsigned ticks, unsigned cpu, til_fb_fragment_t *fragment)
+{
+	checkers_context_t	*ctxt = context;
+	int			state;
+
+	switch (ctxt->setup.pattern) {
+	case CHECKERS_PATTERN_CHECKERED: {
+		unsigned	tiles_per_row;
+
+		tiles_per_row = fragment->frame_width / ctxt->setup.size;
+		if (tiles_per_row * ctxt->setup.size < fragment->frame_width)
+			tiles_per_row++;
+
+		state = (fragment->number + (fragment->y / ctxt->setup.size) * !(tiles_per_row & 0x1)) & 0x1;
+		break;
+	}
+	case CHECKERS_PATTERN_RANDOM:
+		state = hash(fragment->number * 0x61C88647) & 0x1;
+		break;
+	}
+
+	switch (ctxt->setup.dynamics) {
+	case CHECKERS_DYNAMICS_ODD:
+		break;
+	case CHECKERS_DYNAMICS_EVEN:
+		state = ~state & 0x1;
+		break;
+	case CHECKERS_DYNAMICS_ALTERNATING:
+		state ^= ((unsigned)((float)ticks * ctxt->setup.rate) & 0x1);
+		break;
+	case CHECKERS_DYNAMICS_RANDOM: /* note: the big multiply here is just to get up out of the low bits */
+		state &= hash(fragment->number * 0x61C88647 + (unsigned)((float)ticks * ctxt->setup.rate)) & 0x1;
+		break;
+	}
+
+	if (!state)
+		til_fb_fragment_clear(fragment);
+	else
+		til_fb_fragment_fill(fragment, 0xffffffff);
+}
+
+
+static int checkers_setup(const til_settings_t *settings, til_setting_t **res_setting, const til_setting_desc_t **res_desc, void **res_setup)
+{
+	const char	*size;
+	const char	*pattern;
+	const char	*dynamics;
+	const char	*dynamics_rate;
+	const char	*size_values[] = {
+				"4",
+				"8",
+				"16",
+				"32",
+				"64",
+				"128",
+				NULL
+			};
+	const char	*pattern_values[] = {
+				"checkered",
+				"random",
+				NULL
+			};
+	const char	*dynamics_values[] = {
+				"odd",
+				"even",
+				"alternating",
+				"random",
+				NULL
+			};
+	const char	*dynamics_rate_values[] = {
+				"1.0",
+				".75",
+				".5",
+				".25",
+				".1",
+				".01",
+				".001",
+				".0001",
+				NULL
+			};
+	int		r;
+
+	r = til_settings_get_and_describe_value(settings,
+						&(til_setting_desc_t){
+							.name = "Checker size",
+							.key = "size",
+							.regex = "\\.[0-9]+",
+							.preferred = TIL_SETTINGS_STR(CHECKERS_DEFAULT_SIZE),
+							.values = size_values,
+							.annotations = NULL
+						},
+						&size,
+						res_setting,
+						res_desc);
+	if (r)
+		return r;
+
+	r = til_settings_get_and_describe_value(settings,
+						&(til_setting_desc_t){
+							.name = "Checkers pattern",
+							.key = "pattern",
+							.preferred = pattern_values[0],
+							.values = pattern_values,
+							.annotations = NULL
+						},
+						&pattern,
+						res_setting,
+						res_desc);
+	if (r)
+		return r;
+
+	r = til_settings_get_and_describe_value(settings,
+						&(til_setting_desc_t){
+							.name = "Checkers dynamics",
+							.key = "dynamics",
+							.preferred = dynamics_values[0],
+							.values = dynamics_values,
+							.annotations = NULL
+						},
+						&dynamics,
+						res_setting,
+						res_desc);
+	if (r)
+		return r;
+
+	if (strcasecmp(dynamics, "odd") && strcasecmp(dynamics, "even")) {
+		r = til_settings_get_and_describe_value(settings,
+							&(til_setting_desc_t){
+								.name = "Checkers dynamics rate",
+								.key = "dynamics_rate",
+								.preferred = dynamics_rate_values[0],
+								.values = dynamics_rate_values,
+								.annotations = NULL
+							},
+							&dynamics_rate,
+							res_setting,
+							res_desc);
+		if (r)
+			return r;
+	}
+
+	if (res_setup) {
+		checkers_setup_t	*setup;
+
+		setup = calloc(1, sizeof(*setup));
+		if (!setup)
+			return -ENOMEM;
+
+		sscanf(size, "%u", &setup->size);
+
+		if (!strcmp(pattern, "checkered"))
+			setup->pattern = CHECKERS_PATTERN_CHECKERED;
+		else if (!strcmp(pattern, "random"))
+			setup->pattern = CHECKERS_PATTERN_RANDOM;
+		else {
+			free(setup);
+			return -EINVAL;
+		}
+
+		if (!strcmp(dynamics, "odd"))
+			setup->dynamics = CHECKERS_DYNAMICS_ODD;
+		else if (!strcmp(dynamics, "even"))
+			setup->dynamics = CHECKERS_DYNAMICS_EVEN;
+		else if (!strcmp(dynamics, "alternating"))
+			setup->dynamics = CHECKERS_DYNAMICS_ALTERNATING;
+		else if (!strcmp(dynamics, "random"))
+			setup->dynamics = CHECKERS_DYNAMICS_RANDOM;
+		else {
+			free(setup);
+			return -EINVAL;
+		}
+
+		if (setup->dynamics != CHECKERS_DYNAMICS_ODD && setup->dynamics != CHECKERS_DYNAMICS_EVEN)
+			sscanf(dynamics_rate, "%f", &setup->rate);
+
+		*res_setup = setup;
+	}
+
+	return 0;
+}
+
+
+til_module_t	checkers_module = {
+	.create_context = checkers_create_context,
+	.destroy_context = checkers_destroy_context,
+	.prepare_frame = checkers_prepare_frame,
+	.render_fragment = checkers_render_fragment,
+	.name = "checkers",
+	.description = "Checker-patterned overlay (threaded)",
+	.author = "Vito Caputo <vcaputo@pengaru.com>",
+	.setup = checkers_setup,
+};