modules/compose: add a rudimentary compositing module

--module=compose,layers=first:second:third:...

this draws the named modules in the order listed, overdrawing the
output of the previous layers in a cumulative fashion.

5 files changed, 184 insertions, 2 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index d13fdd0..40d3254 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -4,4 +4,4 @@ rototiller_SOURCES = fb.c fb.h fps.c fps.h knobs.h rototiller.c rototiller.h sdl
 if ENABLE_DRM
 rototiller_SOURCES += drm_fb.c
 endif
-rototiller_LDADD = modules/drizzle/libdrizzle.a modules/flui2d/libflui2d.a modules/julia/libjulia.a modules/meta2d/libmeta2d.a modules/montage/libmontage.a modules/pixbounce/libpixbounce.a modules/plasma/libplasma.a modules/ray/libray.a modules/roto/libroto.a modules/rtv/librtv.a modules/snow/libsnow.a modules/sparkler/libsparkler.a modules/spiro/libspiro.a modules/stars/libstars.a modules/submit/libsubmit.a modules/swab/libswab.a libs/grid/libgrid.a libs/puddle/libpuddle.a libs/ray/libray.a libs/sig/libsig.a libs/txt/libtxt.a libs/ascii/libascii.a libs/din/libdin.a -lm
+rototiller_LDADD = modules/compose/libcompose.a modules/drizzle/libdrizzle.a modules/flui2d/libflui2d.a modules/julia/libjulia.a modules/meta2d/libmeta2d.a modules/montage/libmontage.a modules/pixbounce/libpixbounce.a modules/plasma/libplasma.a modules/ray/libray.a modules/roto/libroto.a modules/rtv/librtv.a modules/snow/libsnow.a modules/sparkler/libsparkler.a modules/spiro/libspiro.a modules/stars/libstars.a modules/submit/libsubmit.a modules/swab/libswab.a libs/grid/libgrid.a libs/puddle/libpuddle.a libs/ray/libray.a libs/sig/libsig.a libs/txt/libtxt.a libs/ascii/libascii.a libs/din/libdin.a -lm
diff --git a/src/modules/Makefile.am b/src/modules/Makefile.am
index ad0c7bd..0f60d29 100644
--- a/src/modules/Makefile.am
+++ b/src/modules/Makefile.am
@@ -1 +1 @@
-SUBDIRS = drizzle flui2d julia meta2d montage pixbounce plasma ray roto rtv snow sparkler spiro stars submit swab
+SUBDIRS = compose drizzle flui2d julia meta2d montage pixbounce plasma ray roto rtv snow sparkler spiro stars submit swab
diff --git a/src/modules/compose/Makefile.am b/src/modules/compose/Makefile.am
new file mode 100644
index 0000000..926db7e
--- /dev/null
+++ b/src/modules/compose/Makefile.am
@@ -0,0 +1,3 @@
+noinst_LIBRARIES = libcompose.a
+libcompose_a_SOURCES = compose.c
+libcompose_a_CPPFLAGS = -I@top_srcdir@/src -I@top_srcdir@/src/libs
diff --git a/src/modules/compose/compose.c b/src/modules/compose/compose.c
new file mode 100644
index 0000000..dd85c93
--- /dev/null
+++ b/src/modules/compose/compose.c
@@ -0,0 +1,177 @@
+#include <stdlib.h>
+#include <time.h>
+
+#include "fb.h"
+#include "rototiller.h"
+#include "settings.h"
+#include "txt/txt.h"
+#include "util.h"
+
+/* Copyright (C) 2020 - Vito Caputo <vcaputo@pengaru.com> */
+
+/* This implements a rudimentary compositing module for layering
+ * the output from other modules into a single frame.
+ */
+
+/* some TODOs:
+ * - support randomizing settings and context resets, configurable
+ * - maybe add a way for the user to supply the settings on the cli
+ *   for the composed layers.  That might actually need to be a more
+ *   general solution in the top-level rototiller code, since the
+ *   other meta modules like montage and rtv could probably benefit
+ *   from the ability to feed in settings to the underlying modules.
+ */
+
+typedef struct compose_layer_t {
+	const rototiller_module_t	*module;
+	void				*module_ctxt;
+	char				*settings;
+} compose_layer_t;
+
+typedef struct compose_context_t {
+	unsigned			n_cpus;
+
+	size_t				n_layers;
+	compose_layer_t			layers[];
+} compose_context_t;
+
+static void * compose_create_context(unsigned ticks, unsigned num_cpus);
+static void compose_destroy_context(void *context);
+static void compose_prepare_frame(void *context, unsigned ticks, unsigned n_cpus, fb_fragment_t *fragment, rototiller_fragmenter_t *res_fragmenter);
+static int compose_setup(const settings_t *settings, setting_desc_t **next_setting);
+
+static char	**compose_layers;
+
+
+rototiller_module_t	compose_module = {
+	.create_context = compose_create_context,
+	.destroy_context = compose_destroy_context,
+	.prepare_frame = compose_prepare_frame,
+	.name = "compose",
+	.description = "Layered Modules Compositor",
+	.author = "Vito Caputo <vcaputo@pengaru.com>",
+	.license = "GPLv2",
+	.setup = compose_setup,
+};
+
+
+static void * compose_create_context(unsigned ticks, unsigned num_cpus)
+{
+	compose_context_t	*ctxt;
+	int			n;
+
+	for (n = 0; compose_layers[n]; n++);
+
+	ctxt = calloc(1, sizeof(compose_context_t) + n * sizeof(compose_layer_t));
+	if (!ctxt)
+		return NULL;
+
+	ctxt->n_cpus = num_cpus;
+
+	for (int i = 0; i < n; i++) {
+		const rototiller_module_t	*module;
+
+		module = rototiller_lookup_module(compose_layers[i]);
+
+		ctxt->layers[i].module = module;
+		if (module->create_context)
+			ctxt->layers[i].module_ctxt = module->create_context(ticks, num_cpus);
+
+		ctxt->n_layers++;
+	}
+
+	return ctxt;
+}
+
+
+static void compose_destroy_context(void *context)
+{
+	compose_context_t	*ctxt = context;
+
+	for (int i = 0; i < ctxt->n_layers; i++) {
+		if (ctxt->layers[i].module_ctxt)
+			ctxt->layers[i].module->destroy_context(ctxt->layers[i].module_ctxt);
+	}
+	free(context);
+}
+
+
+static void compose_prepare_frame(void *context, unsigned ticks, unsigned n_cpus, fb_fragment_t *fragment, rototiller_fragmenter_t *res_fragmenter)
+{
+	compose_context_t	*ctxt = context;
+
+	fb_fragment_zero(fragment);
+
+	for (int i = 0; i < ctxt->n_layers; i++)
+		rototiller_module_render(ctxt->layers[i].module, ctxt->layers[i].module_ctxt, ticks, fragment);
+}
+
+
+static int compose_setup(const settings_t *settings, setting_desc_t **next_setting)
+{
+	const char	*layers;
+
+	layers = settings_get_value(settings, "layers");
+	if (!layers) {
+		int	r;
+
+		r = setting_desc_clone(&(setting_desc_t){
+						.name = "Colon-Separated List Of Module Layers, In Draw Order",
+						.key = "layers",
+						.preferred = "drizzle:stars:spiro",
+						.annotations = NULL
+					}, next_setting);
+		if (r < 0)
+			return r;
+
+		return 1;
+	}
+
+	/* turn layers colon-separated list into a null-terminated array of strings */
+	{
+		const rototiller_module_t	**modules;
+		size_t				n_modules;
+		char				*toklayers, *layer;
+		int				n = 2;
+
+		rototiller_get_modules(&modules, &n_modules);
+
+		toklayers = strdup(layers);
+		if (!toklayers)
+			return -ENOMEM;
+
+		layer = strtok(toklayers, ":");
+		do {
+			char	**new;
+			size_t	i;
+
+			/* other meta-modules like montage and rtv may need to
+			 * have some consideration here, but for now I'm just 
+			 * going to let the user potentially compose with montage
+			 * or rtv as one of the layers.
+			 */
+			if (!strcmp(layer, "compose")) /* XXX: prevent infinite recursion */
+				return -EINVAL;
+
+			for (i = 0; i < n_modules; i++) {
+				if (!strcmp(layer, modules[i]->name))
+					break;
+			}
+
+			if (i >= n_modules)
+				return -EINVAL;
+
+			new = realloc(compose_layers, n * sizeof(*compose_layers));
+			if (!new)
+				return -ENOMEM;
+
+			new[n - 2] = layer;
+			new[n - 1] = NULL;
+			n++;
+
+			compose_layers = new;
+		} while (layer = strtok(NULL, ":"));
+	}
+
+	return 0;
+}
diff --git a/src/rototiller.c b/src/rototiller.c
index 579d02a..48056db 100644
--- a/src/rototiller.c
+++ b/src/rototiller.c
@@ -33,6 +33,7 @@ extern fb_ops_t			drm_fb_ops;
 extern fb_ops_t			sdl_fb_ops;
 fb_ops_t			*fb_ops;
 
+extern rototiller_module_t	compose_module;
 extern rototiller_module_t	drizzle_module;
 extern rototiller_module_t	flui2d_module;
 extern rototiller_module_t	julia_module;
@@ -51,6 +52,7 @@ extern rototiller_module_t	submit_module;
 extern rototiller_module_t	swab_module;
 
 static const rototiller_module_t	*modules[] = {
+	&compose_module,
 	&drizzle_module,
 	&flui2d_module,
 	&julia_module,