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.

7 files changed, 44 insertions, 30 deletions

diff --git a/src/modules/sparkler/burst.c b/src/modules/sparkler/burst.c
index 828ca02..72cde03 100644
--- a/src/modules/sparkler/burst.c
+++ b/src/modules/sparkler/burst.c
@@ -23,8 +23,7 @@ static int burst_init(particles_t *particles, particle_t *p)
 	burst_ctxt_t	*ctxt = p->ctxt;
 
 	ctxt->longevity = ctxt->lifetime = BURST_MAX_LIFETIME;
-	p->props->velocity = 0; /* burst should be stationary */
-	p->props->mass = 0; /* no mass prevents gravity's effects */
+	p->props->virtual = 1;
 
 	return 1;
 }
@@ -66,8 +65,8 @@ static void burst_cb(bsp_t *bsp, list_head_t *occupants, void *_s)
 		particle_t	*p = container_of(o, particle_t, occupant);
 		float		d_sq;
 		
-		if (p == s->center) {
-			/* leave ourselves alone */
+		if (p->props->virtual) {
+			/* don't move virtual particles (includes ourself) */
 			continue;
 		}
 
diff --git a/src/modules/sparkler/particle.h b/src/modules/sparkler/particle.h
index 95c117e..c63024d 100644
--- a/src/modules/sparkler/particle.h
+++ b/src/modules/sparkler/particle.h
@@ -12,6 +12,7 @@ typedef struct particle_props_t {
 	float		mass;		/* mass of particle */
 	float		drag;		/* drag of particle */
 	int		of_use:1;	/* are these properties of use/meaningful? */
+	int		virtual:1;	/* is this a virtual particle? (not to be moved or otherwise acted upon) */
 } particle_props_t;
 
 typedef enum particle_status_t {
diff --git a/src/modules/sparkler/particles.c b/src/modules/sparkler/particles.c
index 0eb260e..e504adb 100644
--- a/src/modules/sparkler/particles.c
+++ b/src/modules/sparkler/particles.c
@@ -283,7 +283,40 @@ particle_status_t particles_sim(particles_t *particles)
 }
 
 
-static inline void _particles_age(particles_t *particles, list_head_t *list)
+/* "age" the particle by applying its properties for one step */
+static inline void _particle_age(particles_t *particles, _particle_t *p)
+{
+#if 1
+	if (p->props.mass > 0.0f) {
+		/* gravity, TODO: mass isn't applied. */
+		static v3f_t	gravity = v3f_init(0.0f, -0.05f, 0.0f);
+
+		p->props.direction = v3f_add(&p->props.direction, &gravity);
+		p->props.direction = v3f_normalize(&p->props.direction);
+	}
+#endif
+
+#if 1
+	/* some drag/resistance proportional to velocity TODO: integrate mass */
+	if (p->props.velocity > 0.0f) {
+		p->props.velocity -= ((p->props.velocity * p->props.velocity * p->props.drag));
+		if (p->props.velocity < 0.0f) {
+			p->props.velocity = 0;
+		}
+	}
+#endif
+
+	/* regular movement */
+	if (p->props.velocity > 0.0f) {
+		v3f_t	movement = v3f_mult_scalar(&p->props.direction, p->props.velocity);
+
+		p->props.position = v3f_add(&p->props.position, &movement);
+		bsp_move_occupant(particles->bsp, &p->public.occupant, &p->props.position);
+	}
+}
+
+
+static void _particles_age(particles_t *particles, list_head_t *list)
 {
 	_particle_t	*p;
 
@@ -297,32 +330,9 @@ static inline void _particles_age(particles_t *particles, list_head_t *list)
 	 * particularly good for cache utilization.
 	 */
 	list_for_each_entry(p, list, siblings) {
-#if 1
-		if (p->props.mass > 0.0f) {
-			/* gravity, TODO: mass isn't applied. */
-			static v3f_t	gravity = v3f_init(0.0f, -0.05f, 0.0f);
-
-			p->props.direction = v3f_add(&p->props.direction, &gravity);
-			p->props.direction = v3f_normalize(&p->props.direction);
-		}
-#endif
-
-#if 1
-		/* some drag/resistance proportional to velocity TODO: integrate mass */
-		if (p->props.velocity > 0.0f) {
-			p->props.velocity -= ((p->props.velocity * p->props.velocity * p->props.drag));
-			if (p->props.velocity < 0.0f) {
-				p->props.velocity = 0;
-			}
-		}
-#endif
-
-		/* regular movement */
-		if (p->props.velocity > 0.0f) {
-			v3f_t	movement = v3f_mult_scalar(&p->props.direction, p->props.velocity);
 
-			p->props.position = v3f_add(&p->props.position, &movement);
-			bsp_move_occupant(particles->bsp, &p->public.occupant, &p->props.position);
+		if (!p->props.virtual) {
+			_particle_age(particles, p);
 		}
 
 		if (!list_empty(&p->children)) {
diff --git a/src/modules/sparkler/rocket.c b/src/modules/sparkler/rocket.c
index ae628d3..b56c324 100644
--- a/src/modules/sparkler/rocket.c
+++ b/src/modules/sparkler/rocket.c
@@ -48,6 +48,7 @@ static int rocket_init(particles_t *particles, particle_t *p)
 	ctxt->last_velocity = p->props->velocity;
 	p->props->drag = 0.4;
 	p->props->mass = 0.8;
+	p->props->virtual = 0;
 
 	return 1;
 }
diff --git a/src/modules/sparkler/simple.c b/src/modules/sparkler/simple.c
index 5524282..7c7d415 100644
--- a/src/modules/sparkler/simple.c
+++ b/src/modules/sparkler/simple.c
@@ -46,6 +46,7 @@ static int simple_init(particles_t *particles, particle_t *p)
 
 		p->props->drag = 0.03;
 		p->props->mass = 0.3;
+		p->props->virtual = 0;
 		p->props->of_use = 1;
 	} /* else { we've been given properties, manipulate them or run with them? } */
 
diff --git a/src/modules/sparkler/spark.c b/src/modules/sparkler/spark.c
index aa449c6..16268a9 100644
--- a/src/modules/sparkler/spark.c
+++ b/src/modules/sparkler/spark.c
@@ -24,6 +24,7 @@ static int spark_init(particles_t *particles, particle_t *p)
 
 	p->props->drag = 20.0;
 	p->props->mass = 0.1;
+	p->props->virtual = 0;
 	ctxt->decay_rate = rand_within_range(SPARK_MIN_DECAY_RATE, SPARK_MAX_DECAY_RATE);
 	ctxt->lifetime = ctxt->longevity = rand_within_range(SPARK_MIN_LIFETIME, SPARK_MAX_LIFETIME);
 
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;
 }