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#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include "../umath/vec.h"
#include "fxs.h"
#include "units.h"
void fx_init (fxs *fx) {
fx->bullets = (bullet*)malloc(sizeof(bullet)*FXS_BULLET_MAX);
fx->bulletslen = 0;
fx->explosions = (explosion*)malloc(sizeof(explosion)*FXS_EXPLOSION_MAX);
fx->explosionslen = 0;
}
void fx_add_bullet (fxs *fx, bullet *b) {
if (fx->bulletslen >= FXS_BULLET_MAX-1) return;
fx->bullets[fx->bulletslen] = *b;
fx->bulletslen++;
}
void fx_spread_to_head (float spread, float head[]) {
head[0] = 1-spread; if (spread<0.5) head[0] = spread;
head[1] = 1-spread*2;
vec2_norm(head);
}
/*
* param: pos is the center of the explosion
* param: vel is the heading of the explosion
* param: force is added to vel and scaled by mass
* param: spread [0, 1] is half the angle of the explosion
* param: speed [0, inf] is the initial speed
*/
void fx_explosion_init (fxs *fx, explosion *e,
float pos[], float vel[], float color[], float force[],
float spread, float speed, int n, float time, float lifetime)
{
float normvel[2] = { vel[0], vel[1] }; vec2_norm(normvel);
float perpvel[2] = { normvel[1], -normvel[0] };
e->pos[0] = pos[0]; e->pos[1] = pos[1];
e->partslen = n;
e->force[0] = force[0]; e->force[1] = force[1];
e->starttime = time;
e->friction = 0.95;
for (int j=0; j<n; j++) {
particle *p = e->parts+j;
float sample = rand()%1000/1000.0 * spread;
float head[2]; fx_spread_to_head(sample, head);
if (j%2 == 0) head[0] *= -1;
float dir[2] = {
-head[0]*normvel[1] - head[1]*perpvel[1],
head[0]*normvel[0] + head[1]*perpvel[0]
};
p->lifetime = lifetime;
p->mass = 1;
p->pos[0] = pos[0]; p->pos[1] = pos[1];
p->vel[0] = dir[0]; p->vel[1] = dir[1];
vec2_mul(p->vel, p->vel, speed+(rand()%1000)/1000.0*speed/2);
p->color[0] = color[0];
p->color[1] = color[1];
p->color[2] = color[2];
}
}
void fx_add_explosion (fxs *fx, explosion *e) {
if (fx->explosionslen >= FXS_EXPLOSION_MAX-1) return;
fx->explosions[fx->explosionslen] = *e;
fx->explosionslen++;
}
void fx_process (fxs *fx, float time) {
for (int i=0; i<fx->bulletslen; i++) {
bullet *b = fx->bullets+i;
if (b->starttime > time) continue;
if (time > b->endtime) {
// remove by replacing with last, dont care for order
*b = fx->bullets[fx->bulletslen-1];
fx->bulletslen--;
}
}
for (int i=0; i<fx->explosionslen; i++) {
explosion *e = fx->explosions+i;
if (e->starttime > time) continue;
int sum = e->partslen;
for (int j=0; j<e->partslen; j++) {
if (e->starttime + e->parts[j].lifetime >= time) {
vec2_add(e->parts[j].pos, e->parts[j].pos, e->parts[j].vel);
float forcemass[2];
vec2_mul(forcemass, e->force, e->parts[j].mass);
vec2_add(e->parts[j].vel, e->parts[j].vel, forcemass);
vec2_mul(e->parts[j].vel, e->parts[j].vel, e->friction);
} else { sum -= 1; }
}
if (sum == 0) {
// remove by replacing with last, dont care for order
*e = fx->explosions[fx->explosionslen-1];
fx->explosionslen--;
}
}
}
void fx_render (SDL_Renderer *rend, fxs *fx, float cam[], float time) {
for (int i=0; i<fx->bulletslen; i++) {
bullet *b = fx->bullets+i;
if (b->starttime > time) continue;
float travel_time = b->endtime - b->starttime;
float interval_time = time - b->starttime;
float amt = interval_time / travel_time;
if (amt < 0) amt = 0; if (amt > 1) amt = 1;
float pos[2] = {
b->from[0] *(1-amt) + b->to[0] *amt,
b->from[1] *(1-amt) + b->to[1] *amt
};
float head[2]; vec2_sub(head, b->from, b->to);
float mag = 10;
float dist = amt*vec2_mag(head);
if (dist < 10) { mag = dist; }
vec2_norm(head); vec2_mul(head, head, mag);
SDL_SetRenderDrawColor(rend,
b->color[0], b->color[1], b->color[2], 255);
SDL_RenderDrawLine(rend,
-cam[0] + pos[0],
-cam[1] + pos[1],
-cam[0] + pos[0] + head[0],
-cam[1] + pos[1] + head[1]
);
}
for (int i=0; i<fx->explosionslen; i++) {
explosion *e = fx->explosions+i;
if (e->starttime > time) continue;
for (int j=0; j<e->partslen; j++) {
particle *p = e->parts+j;
if (e->starttime + p->lifetime >= time) {
SDL_SetRenderDrawColor(rend,
p->color[0], p->color[1], p->color[2], 255);
SDL_RenderDrawPoint(rend,
-cam[0] + p->pos[0], -cam[1] + p->pos[1]);
}
}
}
}
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