sparkler: add virtual flag to particle_props_t

The burst particle abused a zero mass to circumvent the effects of aging.

Instead use an explicit virtual flag to suppress aging, change busrt_cb
to ignore all virtual particles instead of only its center.  Previously
burst_cb would thrust other bursts like any other particle, and this was
incorrect.  Now burst centers are always stationary, even when they overlap
other bursts.

1 files changed, 1 insertions, 0 deletions

diff --git a/src/modules/sparkler/xplode.c b/src/modules/sparkler/xplode.c
index 3e3beb4..8b191cd 100644
--- a/src/modules/sparkler/xplode.c
+++ b/src/modules/sparkler/xplode.c
@@ -30,6 +30,7 @@ static int xplode_init(particles_t *particles, particle_t *p)
 
 	p->props->drag = 10.9;
 	p->props->mass = 0.3;
+	p->props->virtual = 0;
 
 	return 1;
 }