Dogcows Code - chaz/yoink/blob - src/engine.cc

   1
   2 /*******************************************************************************
   3
   4  Copyright (c) 2009, Charles McGarvey
   5  All rights reserved.
   6
   7  Redistribution   and   use  in  source  and  binary  forms,  with  or  without
   8  modification, are permitted provided that the following conditions are met:
   9
  10    * Redistributions  of  source  code  must retain the above copyright notice,
  11      this list of conditions and the following disclaimer.
  12    * Redistributions  in binary form must reproduce the above copyright notice,
  13      this  list of conditions and the following disclaimer in the documentation
  14      and/or other materials provided with the distribution.
  15
  16  THIS  SOFTWARE  IS  PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  17  AND  ANY  EXPRESS  OR  IMPLIED  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  19  DISCLAIMED.  IN  NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
  20  FOR  ANY  DIRECT,  INDIRECT,  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  DAMAGES  (INCLUDING,  BUT  NOT  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  22  SERVICES;  LOSS  OF  USE,  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  23  CAUSED  AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  24  OR  TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  25  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26
  27 *******************************************************************************/
  28
  29 #include <iostream>
  30 #include <cstdlib>                      // exit
  31 #include <string>
  32 #include <stdexcept>
  33
  34 #include <SDL/SDL.h>
  35 #include "fastevents.h"
  36
  37 #include "random.hh"
  38 #include "timer.hh"
  39 #include "video.hh"
  40 #include "settings.hh"
  41 #include "dispatcher.hh"
  42
  43 #include "engine.hh"
  44
  45
  46 namespace dc {
  47
  48
  49 class engine::engine_impl
  50 {
  51 public:
  52         engine_impl(const std::string& name, int argc, char* argv[],
  53                         const std::string& configFile, engine* outer) :
  54                 config(argc, argv),
  55                 interface(outer)
  56         {
  57                 if (SDL_Init(SDL_INIT_EVERYTHING | SDL_INIT_EVENTTHREAD) != 0)
  58                 {
  59                         throw std::runtime_error(SDL_GetError());
  60                 }
  61                 if (FE_Init() != 0)
  62                 {
  63                         throw std::runtime_error(FE_GetError());
  64                 }
  65
  66                 rng::seed();
  67
  68                 config.loadFromFile(configFile);
  69
  70                 screen = video_ptr(new video(name));
  71                 screen->makeActive();
  72
  73                 double ts = 0.01;
  74                 config.get("engine.timestep", ts);
  75                 timestep = scalar(ts);
  76
  77                 long maxfps = 40;
  78                 config.getNumber("video.maxfps", maxfps);
  79                 drawrate = 1.0 / scalar(maxfps);
  80
  81                 printfps = false;
  82                 config.get("video.printfps", printfps);
  83         }
  84
  85         ~engine_impl()
  86         {
  87                 // The video object must be destroyed before we can shutdown SDL.
  88                 screen.reset();
  89
  90                 FE_Quit();
  91                 SDL_Quit();
  92         }
  93
  94
  95         /**
  96          * The main loop.  This just calls dispatchEvents(), update(), and draw()
  97          * over and over again.  The timing of the update and draw are decoupled.
  98          * The actual frame rate is also calculated here.  This function will return
  99          * with a value of 0 if the member variable running becomes true.
 100          */
 101
 102         int run()
 103         {
 104                 scalar ticksNow = ticks();
 105
 106                 scalar nextStep = ticksNow;
 107                 scalar nextDraw = ticksNow;
 108                 scalar nextFPSUpdate = ticksNow + 1.0;
 109
 110                 scalar totalTime = 0.0;
 111                 scalar deltaTime = 0.0;
 112                 scalar accumulator = timestep;
 113
 114                 fps = 0;
 115                 int frameAccum = 0;
 116
 117                 running = true;
 118                 do
 119                 {
 120                         scalar newTicks = ticks();
 121                         deltaTime = newTicks - ticksNow;
 122                         ticksNow = newTicks;
 123
 124                         if (deltaTime >= 0.25) deltaTime = 0.25;
 125                         accumulator += deltaTime;
 126
 127                         while (accumulator >= timestep)
 128                         {
 129                                 dispatchEvents();
 130                                 interface->update(totalTime, timestep);
 131
 132                                 totalTime += timestep;
 133                                 accumulator -= timestep;
 134
 135                                 nextStep += timestep;
 136                         }
 137
 138                         if (ticksNow >= nextDraw)
 139                         {
 140                                 frameAccum++;
 141
 142                                 if (ticksNow >= nextFPSUpdate) // determine the actual fps
 143                                 {
 144                                         fps = frameAccum;
 145                                         frameAccum = 0;
 146
 147                                         nextFPSUpdate += 1.0;
 148                                         if (ticksNow >= nextFPSUpdate)
 149                                         {
 150                                                 nextFPSUpdate = ticksNow + 1.0;
 151                                         }
 152
 153                                         if (printfps)
 154                                         {
 155                                                 std::cout << "FPS: " << fps << std::endl;
 156                                         }
 157                                 }
 158
 159                                 interface->draw(accumulator / timestep);
 160                                 screen->swap();
 161
 162                                 nextDraw += drawrate;
 163                                 if (ticksNow >= nextDraw)
 164                                 {
 165                                         // we missed some scheduled draws, so reset the schedule
 166                                         nextDraw = ticksNow + drawrate;
 167                                 }
 168                         }
 169
 170                         // be a good citizen and give back what you don't need
 171                         sleep(std::min(nextStep, nextDraw), true);
 172                 }
 173                 while (running);
 174
 175                 return 0;
 176         }
 177
 178
 179         void dispatchEvents()
 180         {
 181                 SDL_Event e;
 182
 183                 while (FE_PollEvent(&e) == 1)
 184                 {
 185                         switch (e.type)
 186                         {
 187                                 case SDL_KEYDOWN:
 188                                         if (e.key.keysym.sym == SDLK_ESCAPE &&
 189                                                         (SDL_GetModState() & KMOD_CTRL) )
 190                                         {
 191                                            exit(0);
 192                                         }
 193                                         break;
 194
 195                                 case SDL_VIDEORESIZE:
 196                                         screen->resize(e.resize.w, e.resize.h);
 197                                         break;
 198                         }
 199
 200                         interface->handleEvent(e);
 201                 }
 202         }
 203
 204
 205         settings config;
 206         dispatcher relay;
 207         video_ptr screen;
 208
 209         bool running;
 210
 211         scalar timestep;
 212         scalar drawrate;
 213
 214         long fps;
 215         bool printfps;
 216
 217         engine* interface;
 218 };
 219
 220
 221 engine::engine(const std::string& name, int argc, char* argv[],
 222                 const std::string& configFile) :
 223         impl(new engine::engine_impl(name, argc, argv, configFile, this)) {}
 224
 225 engine::~engine() {}
 226
 227
 228 int engine::run()
 229 {
 230         return impl->run();
 231 }
 232
 233 void engine::stop()
 234 {
 235         impl->running = false;
 236 }
 237
 238
 239 void engine::setTimestep(scalar ts)
 240 {
 241         impl->timestep = ts;
 242 }
 243
 244 scalar engine::getTimestep()
 245 {
 246         return impl->timestep;
 247 }
 248
 249 void engine::setMaxFPS(long maxfps)
 250 {
 251         impl->drawrate = 1.0 / scalar(maxfps);
 252 }
 253
 254 long engine::getMaxFPS()
 255 {
 256         return long(1.0 / impl->drawrate);
 257 }
 258
 259
 260 video& engine::getVideo()
 261 {
 262         return *impl->screen;
 263 }
 264
 265 long engine::getFPS()
 266 {
 267         return impl->fps;
 268 }
 269
 270
 271 void engine::update(scalar t, scalar dt) {}
 272 void engine::draw(scalar alpha) {}
 273 void engine::handleEvent(const SDL_Event& e) {}
 274
 275
 276 } // namespace dc
 277
 278 /** vim: set ts=4 sw=4 tw=80: *************************************************/
 279