prosperon/source/engine/particle.c

125 lines
3.6 KiB
C

#include "particle.h"
#include "stb_ds.h"
#include "render.h"
#include "2dphysics.h"
#include "math.h"
#include "log.h"
emitter *make_emitter() {
emitter *e = calloc(sizeof(*e),1);
e->max = 20;
arrsetcap(e->particles, 10);
for (int i = 0; i < arrlen(e->particles); i++)
e->particles[i].life = 0;
e->life = 10;
e->tte = lerp(e->explosiveness, e->life/e->max, 0);
e->scale = 1;
e->speed = 20;
e->buffer = sg_make_buffer(&(sg_buffer_desc){
.size = sizeof(struct par_vert),
.type = SG_BUFFERTYPE_STORAGEBUFFER,
.usage = SG_USAGE_STREAM
});
return e;
}
void emitter_free(emitter *e)
{
arrfree(e->particles);
arrfree(e->verts);
free(e);
}
/* Variate a value around variance. Variance between 0 and 1. */
float variate(float val, float variance)
{
return val + val*(frand(variance)-(variance/2));
}
int emitter_spawn(emitter *e, transform *t)
{
if (arrlen(e->particles) == e->max) return 0;
particle p = {0};
p.life = e->life;
p.pos = (HMM_Vec4){t->pos.x,t->pos.y,t->pos.z,0};
HMM_Vec3 up = trans_forward(t);
float newan = (frand(e->divergence)-(e->divergence/2))*HMM_TurnToRad;
HMM_Vec2 v2n = HMM_V2Rotate((HMM_Vec2){0,1}, newan);
HMM_Vec3 norm = (HMM_Vec3){v2n.x, v2n.y,0};
p.v = HMM_MulV4F((HMM_Vec4){norm.x,norm.y,norm.z,0}, variate(e->speed, e->variation));
p.angle = 0.25;
p.scale = variate(e->scale*t->scale.x, e->scale_var);
arrput(e->particles,p);
return 1;
}
void emitter_emit(emitter *e, int count, transform *t)
{
for (int i = 0; i < count; i++)
emitter_spawn(e, t);
}
void emitter_draw(emitter *e)
{
if (arrlen(e->particles) == 0) return;
arrsetlen(e->verts, arrlen(e->particles));
for (int i = 0; i < arrlen(e->particles); i++) {
if (e->particles[i].time >= e->particles[i].life) continue;
particle *p = e->particles+i;
e->verts[i].pos = p->pos.xy;
e->verts[i].angle = p->angle;
e->verts[i].scale = p->scale;
/* if (p->time < e->grow_for)
e->verts[i].scale = lerp(p->time/e->grow_for, 0, p->scale);
else if (p->time > (p->life - e->shrink_for))
e->verts[i].scale = lerp((p->time-(p->life-e->shrink_for))/e->shrink_for, p->scale, 0);*/
e->verts[i].color = p->color;
}
sg_range verts;
verts.ptr = e->verts;
verts.size = sizeof(*e->verts)*arrlen(e->verts);
if (sg_query_buffer_will_overflow(e->buffer, verts.size)) {
sg_destroy_buffer(e->buffer);
e->buffer = sg_make_buffer(&(sg_buffer_desc){
.size = verts.size,
.type = SG_BUFFERTYPE_STORAGEBUFFER,
.usage = SG_USAGE_STREAM
});
}
sg_append_buffer(e->buffer, &verts);
}
void emitter_step(emitter *e, double dt, transform *t) {
HMM_Vec4 g_accel = HMM_MulV4F((HMM_Vec4){cpSpaceGetGravity(space).x, cpSpaceGetGravity(space).y, 0, 0}, dt);
for (int i = 0; i < arrlen(e->particles); i++) {
if (e->particles[i].time >= e->particles[i].life) continue;
//if (e->warp_mask & gravmask)
// e->particles[i].v = HMM_AddV4(e->particles[i].v, g_accel);
e->particles[i].pos = HMM_AddV4(e->particles[i].pos, HMM_MulV4F(e->particles[i].v, dt));
e->particles[i].angle += e->particles[i].av*dt;
e->particles[i].time += dt;
e->particles[i].color = sample_sampler(&e->color, e->particles[i].time/e->particles[i].life);
e->particles[i].scale = e->scale;
if (e->particles[i].time >= e->particles[i].life)
arrdelswap(e->particles, i);
// else if (query_point(e->particles[i].pos.xy))
// arrdelswap(e->particles,i);
}
e->tte-=dt;
float step = lerp(e->explosiveness, e->life/e->max,0);
while (e->tte <= 0) {
e->tte += step;
if (!emitter_spawn(e, t)) break;
}
}