1 files changed, 22 insertions, 0 deletions

diff --git a/src/modules/checkers/checkers.c b/src/modules/checkers/checkers.c
index 27da42b..c4e02c1 100644
--- a/src/modules/checkers/checkers.c
+++ b/src/modules/checkers/checkers.c
@@ -38,6 +38,7 @@ typedef enum checkers_dynamics_t {
 	CHECKERS_DYNAMICS_EVEN,
 	CHECKERS_DYNAMICS_ALTERNATING,
 	CHECKERS_DYNAMICS_RANDOM,
+	CHECKERS_DYNAMICS_SONAR,
 } checkers_dynamics_t;
 
 typedef struct checkers_setup_t {
@@ -49,6 +50,7 @@ typedef struct checkers_setup_t {
 } checkers_setup_t;
 
 typedef struct checkers_context_t {
+	unsigned		tickoff;
 	checkers_setup_t	setup;
 } checkers_context_t;
 
@@ -73,6 +75,7 @@ static void * checkers_create_context(unsigned ticks, unsigned n_cpus, til_setup
 		return NULL;
 
 	ctxt->setup = *(checkers_setup_t *)setup;
+	ctxt->tickoff = ticks;
 
 	return ctxt;
 }
@@ -142,6 +145,22 @@ static void checkers_render_fragment(void *context, unsigned ticks, unsigned cpu
 	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;
+	case CHECKERS_DYNAMICS_SONAR: {
+		float	t = (float)((ticks - ctxt->tickoff) % 1000) * .001f * 2;
+		float	dist_sq, x, y;
+
+		x = fragment->x + (fragment->width >> 1);
+		y = fragment->y + (fragment->height >> 1);
+		x = x / (float)fragment->frame_width * 2.f - 1.f;
+		y = y / (float)fragment->frame_height * 2.f - 1.f;
+
+		dist_sq = x * x + y * y;
+
+		t *= t;
+
+		state &= (dist_sq > (t - .1f) && dist_sq < (t + .1f));
+		break;
+	}
 	}
 
 	if (!state)
@@ -176,6 +195,7 @@ static int checkers_setup(const til_settings_t *settings, til_setting_t **res_se
 				"even",
 				"alternating",
 				"random",
+				"sonar",
 				NULL
 			};
 	const char	*dynamics_rate_values[] = {
@@ -276,6 +296,8 @@ static int checkers_setup(const til_settings_t *settings, til_setting_t **res_se
 			setup->dynamics = CHECKERS_DYNAMICS_ALTERNATING;
 		else if (!strcmp(dynamics, "random"))
 			setup->dynamics = CHECKERS_DYNAMICS_RANDOM;
+		else if (!strcmp(dynamics, "sonar"))
+			setup->dynamics = CHECKERS_DYNAMICS_SONAR;
 		else {
 			free(setup);
 			return -EINVAL;