prosperon/source/engine/particle.h

#ifndef PARTICLE_H
#define PARTICLE_H

#include "HandmadeMath.h"
#include "warp.h"
#include "transform.h"
#include "texture.h"
#include "anim.h"
#include "gameobject.h"
#include "render.h"

typedef struct particle {
  HMM_Vec4 pos;
  HMM_Vec4 v; /* velocity */
  float angle;
  float av; /* angular velocity */
  float scale;
  double time;
  double life;
  HMM_Vec4 color;
} particle;

#define SPRAY 0
#define CLOUD 1
#define MESH 2

typedef struct par_vert {
  HMM_Vec2 pos;
  float angle;
  float scale;
  struct rgba color;
} par_vert;

typedef struct emitter {
  struct particle *particles;
  par_vert *verts;
  HMM_Vec3 *mesh; /* list of points to optionally spawn from */
  HMM_Vec3 *norm; /* norm at each point */
  int type; /* spray, cloud, or mesh */
  float explosiveness; /* 0 for a stream, 1 for all at once. Range of values allowed. */
  int max; /* number of particles */
  double life; /* how long a particle lasts */
  double life_var;
  /* SPRAY PARTICLE GEN */
  float speed; /* initial speed of particle */
  float variation; /* variation on speed */
  float divergence; /* angular degree of variation from emitter normal, up to 1 */
  float tumble; /* amount of random rotation of particles */
  float tumble_rate; /* tumble rotation */
  sampler color; /* color over particle lifetime */
  float scale;
  float scale_var;
  float grow_for; /* seconds to grow from small until scale */
  float shrink_for; /* seconds to shrink to small prior to its death */
  /* ROTATION AND COLLISION */
  int collision_mask; /* mask for collision */
  float bounce; /* bounce back after collision */
  /* PARTICLE SPAWN */
  int die_after_collision;
  float persist; /* how long to linger after death */
  float persist_var;
  /* TRAILS */
  warpmask warp_mask;
  double tte; /* time to emit */ 
  sg_buffer buffer; 
} emitter;

emitter *make_emitter();
void emitter_free(emitter *e);

void emitter_emit(emitter *e, int count, transform2d *t);
void emitter_step(emitter *e, double dt, transform2d *t);
void emitter_draw(emitter *e, sg_bindings bind);

#endif