sparkler: introduce a particle system

A while ago I made this particle system on SDL, and had the beginnings of
an octree implemented within it, but never finished actually using the
octree to accelerate the proximity searches.

This now has the octree completed and of course more particle interactions now
that neighbors could be found more quickly.

The simulation somewhat resembles a fireworks display.  Every particle is drawn
as a single pixel.  The visual effect is dominated by spontaneously spawned
rockets which explode into thousands of particles accompanied by bursts that
thrust particles away from the explosion radially in an expanding sphere
resembling a shock wave.  When the shock wave happens to strike another rocket,
it explodes, resulting in another shock wave.  This can produce spectacular
chain reactions, so it's worth running for some time and seeing what transpires.

1 files changed, 28 insertions, 0 deletions

diff --git a/modules/sparkler/bsp.h b/modules/sparkler/bsp.h
new file mode 100644
index 0000000..f5ce303
--- /dev/null
+++ b/modules/sparkler/bsp.h
@@ -0,0 +1,28 @@
+#ifndef _BSP_H
+#define _BSP_H
+
+#include <stdint.h>
+
+#include "list.h"
+#include "v3f.h"
+
+typedef struct bsp_t bsp_t;
+typedef struct bsp_node_t bsp_node_t;
+
+/* Embed this in anything you want spatially indexed by the bsp tree. */
+/* TODO: it would be nice to make this opaque, but it's a little annoying. */
+typedef struct bsp_occupant_t {
+	bsp_node_t	*leaf;		/* leaf node containing this occupant */
+	list_head_t	occupants;	/* node on containing leaf node's list of occupants */
+	v3f_t		*position;	/* position of occupant to be partitioned */
+} bsp_occupant_t;
+
+bsp_t * bsp_new(void);
+void bsp_free(bsp_t *bsp);
+void bsp_print(bsp_t *bsp);
+void bsp_add_occupant(bsp_t *bsp, bsp_occupant_t *occupant, v3f_t *position);
+void bsp_delete_occupant(bsp_t *bsp, bsp_occupant_t *occupant);
+void bsp_move_occupant(bsp_t *bsp, bsp_occupant_t *occupant, v3f_t *position);
+void bsp_search_sphere(bsp_t *bsp, v3f_t *center, float radius_min, float radius_max, void (*cb)(bsp_t *, list_head_t *, void *), void *cb_data);
+
+#endif