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