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#include <stdlib.h>
#include "draw.h"
#include "particle.h"
#include "particles.h"
/* a "xplode" particle type, emitted by rockets in large numbers at the end of their lifetime */
#define XPLODE_MAX_DECAY_RATE 10
#define XPLODE_MIN_DECAY_RATE 5
#define XPLODE_MAX_LIFETIME 150
#define XPLODE_MIN_LIFETIME 5
extern particle_ops_t spark_ops;
particle_ops_t xplode_ops;
typedef struct _xplode_ctxt_t {
int decay_rate;
int longevity;
int lifetime;
} xplode_ctxt_t;
static int xplode_init(particles_t *particles, particle_t *p)
{
xplode_ctxt_t *ctxt = p->ctxt;
ctxt->decay_rate = rand_within_range(XPLODE_MIN_DECAY_RATE, XPLODE_MAX_DECAY_RATE);
ctxt->lifetime = ctxt->longevity = rand_within_range(XPLODE_MIN_LIFETIME, XPLODE_MAX_LIFETIME);
p->props->drag = 10.9;
p->props->mass = 0.3;
return 1;
}
static particle_status_t xplode_sim(particles_t *particles, particle_t *p)
{
xplode_ctxt_t *ctxt = p->ctxt;
if (!ctxt->longevity || (ctxt->longevity -= ctxt->decay_rate) <= 0) {
ctxt->longevity = 0;
return PARTICLE_DEAD;
}
/* litter some small sparks behind the explosion particle */
if (!(ctxt->lifetime % 30)) {
particle_props_t props = *p->props;
props.velocity = (float)rand_within_range(10, 50) / 10000.0;
particles_spawn_particle(particles, p, &props, &xplode_ops);
}
return PARTICLE_ALIVE;
}
static void xplode_draw(particles_t *particles, particle_t *p, int x, int y, fb_fragment_t *f)
{
xplode_ctxt_t *ctxt = p->ctxt;
uint32_t color;
if (ctxt->longevity == ctxt->lifetime) {
color = makergb(0xff, 0xff, 0xa0, 1.0);
} else {
color = makergb(0xff, 0xff, 0x00, ((float)ctxt->longevity / ctxt->lifetime));
}
if (!draw_pixel(f, x, y, color)) {
/* offscreen */
ctxt->longevity = 0;
}
}
particle_ops_t xplode_ops = {
.context_size = sizeof(xplode_ctxt_t),
.sim = xplode_sim,
.init = xplode_init,
.draw = xplode_draw,
.cleanup = NULL,
};
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