textpsys: 4b1360a5d54d src/psys.cc

textpsys

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author	John Tsiombikas <nuclear@member.fsf.org>
date	Thu, 20 Aug 2015 04:52:30 +0300
parents	a4ffd9e6984c
children

line source

1 #include <stdio.h>

2 #include <stdlib.h>

3 #include <vector>

4 #include <algorithm>

5 #include "opengl.h"

6 #include "psys.h"

8 #define MAX_SPAWNMAP_SAMPLES 2048

10 static double frand();

11 static float rndval(float x, float range);

12 static Particle *palloc();

13 static void pfree(Particle *p);

14 static void pfreelist(Particle *p);

16 void psys_default(PSysParam *pp)

17 {

18 // default parameters

19 pp->spawn_rate = 10.0;

20 pp->spawn_range = 0.0;

21 pp->life = 1.0;

22 pp->life_range = 0.0;

23 pp->size = 1.0;

24 pp->size_range = 0.0;

25 pp->spawn_map = 0;

26 pp->spawn_map_speed = 0.0;

28 pp->gravity = Vector3(0, -9.2, 0);

30 pp->pimg = 0;

31 pp->pcolor_start = pp->pcolor_mid = pp->pcolor_end = Vector3(1, 1, 1);

32 pp->palpha_start = 1.0;

33 pp->palpha_mid = 0.5;

34 pp->palpha_end = 0.0;

35 pp->pscale_start = pp->pscale_mid = pp->pscale_end = 1.0;

36 }

38 ParticleSystem::ParticleSystem()

39 {

40 active = true;

41 active_time = 0.0f;

42 spawn_pending = 0.0f;

43 plist = 0;

44 pcount = 0;

45 smcache = 0;

47 expl = false;

48 expl_force = expl_dur = 0.0f;

49 expl_life = 0.0f;

51 psys_default(&pp);

52 }

54 ParticleSystem::~ParticleSystem()

55 {

56 pfreelist(plist);

57 delete [] smcache;

58 }

60 void ParticleSystem::reset()

61 {

62 pfreelist(plist);

63 delete [] smcache;

64 smcache = 0;

66 active = true;

67 active_time = 0.0f;

68 spawn_pending = 0.0f;

70 psys_default(&pp);

71 }

73 void ParticleSystem::explode(const Vector3 &c, float force, float dur, float life)

74 {

75 if(expl) return;

77 expl_dur = dur;

78 expl_force = force;

79 expl_cent = c;

80 expl_life = life;

81 expl = true;

82 }

84 bool ParticleSystem::alive() const

85 {

86 return active || pcount > 0;

87 }

89 void ParticleSystem::update(float dt)

90 {

91 if(pp.spawn_map && !smcache) {

92 gen_spawnmap(MAX_SPAWNMAP_SAMPLES);

93 }

95 if(active) {

96 active_time += dt;

97 }

99 if(expl) {

100 expl = false;

101 //active = false;

102

103 Vector3 cent = expl_cent + pos;

104

105 Particle *p = plist;

106 while(p) {

107 p->max_life = expl_dur;

108 Vector3 dir = p->pos - cent;

109 p->vel += (normalize(dir + Vector3((frand() - 0.5) * 0.5, frand() - 0.5, (frand() - 0.5) * 0.5))) * expl_force;

110 p = p->next;

111 }

112 }

113

114 if(expl_life > 0.0) {

115 expl_life -= dt;

116 if(expl_life <= 0.0) {

117 expl_life = 0.0;

118 active = false;

119 }

120 }

121

122 // update active particles

123 Particle *p = plist;

124 while(p) {

125 p->life += dt;

126 if(p->life < p->max_life) {

127 float t = p->life / p->max_life;

128

129 p->pos = p->pos + p->vel * dt;

130 p->vel = p->vel + pp.gravity * dt;

131

132 if(t < 0.5) {

133 t *= 2.0;

134 p->color = lerp(pp.pcolor_start, pp.pcolor_mid, t);

135 p->alpha = lerp(pp.palpha_start, pp.palpha_mid, t);

136 p->scale = lerp(pp.pscale_start, pp.pscale_mid, t);

137 } else {

138 t = (t - 0.5) * 2.0;

139 p->color = lerp(pp.pcolor_mid, pp.pcolor_end, t);

140 p->alpha = lerp(pp.palpha_mid, pp.palpha_end, t);

141 p->scale = lerp(pp.pscale_mid, pp.pscale_end, t);

142 }

143

144 } else {

145 p->life = -1.0;

146 }

147 p = p->next;

148 }

149

150 // remove dead particles

151 Particle dummy;

152 dummy.next = plist;

153 p = &dummy;

154 while(p->next) {

155 if(p->next->life < 0.0) {

156 Particle *tmp = p->next;

157 p->next = tmp->next;

158 pfree(tmp);

159 --pcount;

160 } else {

161 p = p->next;

162 }

163 }

164 plist = dummy.next;

165

166 float spawn_rate = pp.spawn_rate;

167 if(pp.spawn_map && pp.spawn_map_speed > 0.0) {

168 float s = active_time * pp.spawn_map_speed;

169 if(s > 1.0) s = 1.0;

170 spawn_rate *= s;

171 }

172

173 // spawn particles as needed

174 if(active) {

175 spawn_pending += spawn_rate * dt;

176

177 while(spawn_pending >= 1.0f) {

178 spawn_pending -= 1.0f;

179 spawn_particle();

180 }

181 }

182 }

183

184 void ParticleSystem::draw() const

185 {

186 int cur_sdr = 0;

187 glGetIntegerv(GL_CURRENT_PROGRAM, &cur_sdr);

188 if(cur_sdr) {

189 glUseProgram(0);

190 }

191

192 glPushAttrib(GL_ENABLE_BIT | GL_COLOR_BUFFER_BIT);

193 glDisable(GL_LIGHTING);

194 glEnable(GL_BLEND);

195 glBlendFunc(GL_SRC_ALPHA, GL_ONE);

196

197 if(pp.pimg) {

198 if(!pp.pimg->texture) {

199 pp.pimg->gen_texture();

200 }

201 glEnable(GL_TEXTURE_2D);

202 glBindTexture(GL_TEXTURE_2D, pp.pimg->texture);

203 }

204

205 glBegin(GL_QUADS);

206 Particle *p = plist;

207 while(p) {

208 float hsz = p->size * p->scale * 0.5;

209 glColor4f(p->color.x, p->color.y, p->color.z, p->alpha);

210 glTexCoord2f(0, 0); glVertex3f(p->pos.x - hsz, p->pos.y - hsz, p->pos.z);

211 glTexCoord2f(1, 0); glVertex3f(p->pos.x + hsz, p->pos.y - hsz, p->pos.z);

212 glTexCoord2f(1, 1); glVertex3f(p->pos.x + hsz, p->pos.y + hsz, p->pos.z);

213 glTexCoord2f(0, 1); glVertex3f(p->pos.x - hsz, p->pos.y + hsz, p->pos.z);

214 p = p->next;

215 }

216 glEnd();

217

218 glPopAttrib();

219

220 if(cur_sdr) {

221 glUseProgram(cur_sdr);

222 }

223 }

224

225 void ParticleSystem::gen_spawnmap(int count)

226 {

227 Image *img = pp.spawn_map;

228 if(!img) return;

229

230 delete [] smcache;

231 smcache = new Vector3[count];

232

233 float umax = (float)img->width;

234 float vmax = (float)img->height;

235 float aspect = umax / vmax;

236

237 // first generate a bunch of random samples by rejection sampling

238 printf("generating %d random spawnmap samples\n", count);

239 for(int i=0; i<count; i++) {

240 float u, v;

241 unsigned char val, ord;

242

243 do {

244 u = (double)rand() / (double)RAND_MAX;

245 v = (double)rand() / (double)RAND_MAX;

246

247 int x = (int)(u * umax);

248 int y = (int)(v * vmax);

249

250 unsigned char *pptr = img->pixels + (y * img->width + x) * 3;

251 val = pptr[0];

252 ord = pptr[1];

253 } while(val < 192);

254

255 smcache[i] = Vector3(u * 2.0 - 1.0, (1.0 - v * 2.0) / aspect, ord / 255.0);

256 }

257

258 // then order by z

259 std::sort(smcache, smcache + count,

260 [](const Vector3 &a, const Vector3 &b) { return a.z < b.z; });

261

262 // precalculate the bounds of each slot

263 smcache_max[0] = 0;

264 for(int i=1; i<255; i++) {

265 float maxval = (float)i / 255.0;

266

267 int idx = smcache_max[i - 1];

268 while(++idx < count && smcache[idx].z < maxval);

269 smcache_max[i] = idx;

270 }

271 smcache_max[255] = count;

272 }

273

274 static double frand()

275 {

276 return (double)rand() / (double)RAND_MAX;

277 }

278

279 static float rndval(float x, float range)

280 {

281 if(fabs(range) < 1e-6) {

282 return x;

283 }

284 return x + (frand() * range - range * 0.5);

285 }

286

287 void ParticleSystem::spawn_particle()

288 {

289 Particle *p = palloc();

290 p->pos = Vector3(rndval(pos.x, pp.spawn_range),

291 rndval(pos.y, pp.spawn_range),

292 rndval(pos.z, pp.spawn_range));

293 p->vel = Vector3(0, 0, 0);

294 p->color = pp.pcolor_start;

295 p->alpha = pp.palpha_start;

296 p->life = 0.0;

297 p->max_life = rndval(pp.life, pp.life_range);

298 p->size = rndval(pp.size, pp.size_range);

299 p->scale = pp.pscale_start;

300

301 if(pp.spawn_map) {

302 float maxz = pp.spawn_map_speed > 0.0 ? active_time * pp.spawn_map_speed : 1.0;

303 int max_idx = (int)(maxz * 255.0);

304 if(max_idx > 255) max_idx = 255;

305 if(max_idx < 1) max_idx = 1;

306

307 int idx = rand() % smcache_max[max_idx];

308

309 p->pos.x += smcache[idx].x;

310 p->pos.y += smcache[idx].y;

311 }

312

313 p->next = plist;

314 plist = p;

315 ++pcount;

316 }

317

318 // particle allocator

319 #define MAX_POOL_SIZE 8192

320 static Particle *ppool;

321 static int ppool_size;

322

323 static Particle *palloc()

324 {

325 if(ppool) {

326 Particle *p = ppool;

327 ppool = ppool->next;

328 --ppool_size;

329 return p;

330 }

331 return new Particle;

332 }

333

334 static void pfree(Particle *p)

335 {

336 if(!p) return;

337

338 if(ppool_size < MAX_POOL_SIZE) {

339 p->next = ppool;

340 ppool = p;

341 ++ppool_size;

342 } else {

343 delete p;

344 }

345 }

346

347 static void pfreelist(Particle *p)

348 {

349 if(!p) return;

350

351 Particle *it = p;

352 int new_pool_size = ppool_size;

353

354 while(it->next && new_pool_size < MAX_POOL_SIZE) {

355 it = it->next;

356 ++new_pool_size;

357 }

358

359 Particle *last = it;

360 it = it->next;

361

362 // add the first lot to the pool

363 last->next = ppool;

364 ppool = p;

365 ppool_size = new_pool_size;

366

367 // delete the rest;

368 while(it) {

369 p = it;

370 it = it->next;

371 delete p;

372 }

373 }