1 files changed, 342 insertions, 0 deletions
diff --git a/src/modules/sparkler/particles.c b/src/modules/sparkler/particles.c
new file mode 100644
index 0000000..0eb260e
--- /dev/null
+++ b/src/modules/sparkler/particles.c
@@ -0,0 +1,342 @@
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <math.h>
+#include <stdlib.h>
+#include <time.h>
+
+#include "fb.h"
+
+#include "chunker.h"
+#include "container.h"
+#include "bsp.h"
+#include "list.h"
+#include "particle.h"
+#include "particles.h"
+#include "v3f.h"
+
+#define ZCONST	0.4f
+
+/* private particle with all the particles bookkeeping... */
+typedef struct _particle_t {
+	list_head_t		siblings;	/* sibling particles */
+	list_head_t		children;	/* children particles */
+
+	particle_props_t	props;		/* we reference this in the public particle, I might change
+						 * the way props are allocated so coding everything to use a
+						 * reference for now.  It may make sense to have props allocated
+						 * separately via their own chunker, and perform some mass operations
+						 * against the list of chunks rather than chasing the pointers of
+						 * the particle heirarchy. TODO
+						 */
+	particle_t		public;		/* the public particle_t is embedded */
+
+	uint8_t			context[];	/* particle type-specific context [public.ops.context_size] */
+} _particle_t;
+
+struct particles_t {
+	chunker_t		*chunker;	/* chunker for variably-sized particle allocation (includes context) */
+	list_head_t		active;		/* top-level active list of particles heirarchy */
+	bsp_t			*bsp;		/* bsp spatial index of the particles */
+};
+
+
+/* create a new particle system */
+particles_t * particles_new(void)
+{
+	particles_t	*particles;
+
+	particles = calloc(1, sizeof(particles_t));
+	if (!particles) {
+		return NULL;
+	}
+
+	particles->chunker = chunker_new(sizeof(_particle_t) * 128);
+	if (!particles->chunker) {
+		return NULL;
+	}
+
+	particles->bsp = bsp_new();
+	if (!particles->bsp) {
+		return NULL;
+	}
+
+	INIT_LIST_HEAD(&particles->active);
+
+	return particles;
+}
+
+
+/* TODO: add a public interface for destroying particles?  for now we just return PARTICLE_DEAD in the sim */
+static inline void _particles_free_particle(particles_t *particles, _particle_t *p)
+{
+	assert(p);
+
+	particle_cleanup(particles, &p->public);
+	chunker_free(p);
+}
+
+
+static inline void _particles_free(particles_t *particles, list_head_t *list)
+{
+	_particle_t	*p, *_p;
+
+	assert(particles);
+	assert(list);
+
+	list_for_each_entry_safe(p, _p, list, siblings) {
+		_particles_free(particles, &p->children);
+		_particles_free_particle(particles, p);
+	}
+}
+
+
+/* free up all the particles */
+void particles_free(particles_t *particles)
+{
+	assert(particles);
+
+	_particles_free(particles, &particles->active);
+}
+
+
+/* reclaim a dead particle, moving it to the free list */
+static void particles_reap_particle(particles_t *particles, _particle_t *particle)
+{
+	assert(particles);
+	assert(particle);
+
+	if (!list_empty(&particle->children)) {
+		/* adopt any orphaned children using the global parts list */
+		list_splice(&particle->children, &particles->active);
+	}
+
+	list_del(&particle->siblings);
+	bsp_delete_occupant(particles->bsp, &particle->public.occupant);
+	_particles_free_particle(particles, particle);
+}
+
+
+/* add a particle to the specified list */
+static inline int _particles_add_particle(particles_t *particles, list_head_t *list, particle_props_t *props, particle_ops_t *ops)
+{
+	_particle_t	*p;
+
+	assert(particles);
+	assert(ops);
+	assert(list);
+
+	p = chunker_alloc(particles->chunker, sizeof(_particle_t) + ops->context_size);
+	if (!p) {
+		return 0;
+	}
+
+	INIT_LIST_HEAD(&p->children);
+	INIT_LIST_HEAD(&p->siblings);
+
+	/* inherit the parent's properties and ops if they're not explicitly provided */
+	if (props) {
+		p->props = *props;
+	} else {
+		p->props.of_use = 0;
+	}
+
+	p->public.props = &p->props;
+	p->public.ops = ops;
+
+	if (ops->context_size) {
+		p->public.ctxt = p->context;
+	}
+
+	if (!particle_init(particles, &p->public)) {
+		/* XXX FIXME this shouldn't be normal, we don't want to allocate
+		 * particles that cannot be initialized.  the rockets today set a cap
+		 * by failing initialization, that's silly. */
+		chunker_free(p);
+		return 0;
+	}
+
+	p->public.props->of_use = 1;
+	list_add(&p->siblings, list);
+	bsp_add_occupant(particles->bsp, &p->public.occupant, &p->props.position);
+
+	return 1;
+}
+
+
+/* add a new "top-level" particle of the specified props and ops taking from the provided parts list */
+int particles_add_particle(particles_t *particles, particle_props_t *props, particle_ops_t *ops)
+{
+	assert(particles);
+
+	return _particles_add_particle(particles, &particles->active, props, ops);
+}
+
+
+/* spawn a new child particle from a parent, initializing it via inheritance if desired */
+void particles_spawn_particle(particles_t *particles, particle_t *parent, particle_props_t *props, particle_ops_t *ops)
+{
+	_particle_t	*p = container_of(parent, _particle_t, public);
+
+	assert(particles);
+	assert(parent);
+
+	_particles_add_particle(particles, &p->children, props ? props : parent->props, ops ? ops : parent->ops);
+}
+
+
+/* plural version of particle_add(); adds multiple "top-level" particles of uniform props and ops */
+void particles_add_particles(particles_t *particles, particle_props_t *props, particle_ops_t *ops, int num)
+{
+	int	i;
+
+	assert(particles);
+
+	for (i = 0; i < num; i++) {
+		_particles_add_particle(particles, &particles->active, props, ops);
+	}
+}
+
+
+/* Simple accessor to get the bsp pointer, the bsp is special because we don't want to do
+ * callbacks per-occupant, so the bsp_occupant_t and search functions are used directly by
+ * the per-particle code needing nearest-neighbor search.  that requires an accessor since
+ * particles_t is opaque.  This seemed less shitty than opening up particles_t.
+ */
+bsp_t * particles_bsp(particles_t *particles)
+{
+	assert(particles);
+	assert(particles->bsp);
+
+	return particles->bsp;
+}
+
+
+static inline void _particles_draw(particles_t *particles, list_head_t *list, fb_fragment_t *fragment)
+{
+	float		w2 = fragment->width * .5f, h2 = fragment->height * .5f;
+	_particle_t	*p;
+
+	assert(particles);
+	assert(list);
+	assert(fragment);
+
+	list_for_each_entry(p, list, siblings) {
+		int	x, y;
+
+		/* project the 3d coordinates onto the 2d plane */
+		x = (p->props.position.x / (p->props.position.z - ZCONST) * w2) + w2;
+		y = (p->props.position.y / (p->props.position.z - ZCONST) * h2) + h2;
+
+		particle_draw(particles, &p->public, x, y, fragment);
+
+		if (!list_empty(&p->children)) {
+			_particles_draw(particles, &p->children, fragment);
+		}
+	}
+}
+
+
+/* draw all of the particles, currently called in heirarchical order */
+void particles_draw(particles_t *particles, fb_fragment_t *fragment)
+{
+	assert(particles);
+
+	_particles_draw(particles, &particles->active, fragment);
+}
+
+
+static inline particle_status_t _particles_sim(particles_t *particles, list_head_t *list)
+{
+	particle_status_t	ret = PARTICLE_DEAD, s;
+	_particle_t		*p, *_p;
+
+	assert(particles);
+	assert(list);
+
+	list_for_each_entry_safe(p, _p, list, siblings) {
+		if ((s = particle_sim(particles, &p->public)) == PARTICLE_ALIVE) {
+			ret = PARTICLE_ALIVE;
+
+			if (!list_empty(&p->children) &&
+			    _particles_sim(particles, &p->children) == PARTICLE_ALIVE) {
+				ret = PARTICLE_ALIVE;
+			}
+		} else {
+			particles_reap_particle(particles, p);
+		}
+	}
+
+	return ret;
+}
+
+
+/* simulate the particles, call the sim method of every particle in the heirarchy, this is what makes the particles dynamic */
+/* if any paticle is still living, we return PARTICLE_ALIVE, to inform the caller when everything's dead */
+particle_status_t particles_sim(particles_t *particles)
+{
+	assert(particles);
+
+	return _particles_sim(particles, &particles->active);
+}
+
+
+static inline void _particles_age(particles_t *particles, list_head_t *list)
+{
+	_particle_t	*p;
+
+	assert(particles);
+	assert(list);
+
+	/* TODO: since this *only* involves the properties struct, if they were
+	 * allocated from a separate slab containing only properties, it'd be
+	 * more efficient to iterate across property arrays and skip inactive
+	 * entries.  This heirarchical pointer-chasing recursion isn't
+	 * 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 (!list_empty(&p->children)) {
+			_particles_age(particles, &p->children);
+		}
+	}
+}
+
+
+/* advance time for all the particles (move them), this doesn't currently invoke any part-specific helpers, it's just applying
+ * physics-type stuff, moving particles according to their velocities, directions, mass, drag, gravity etc... */
+void particles_age(particles_t *particles)
+{
+	assert(particles);
+
+	_particles_age(particles, &particles->active);
+}