src/swarm.cpp

   1 #include <stdio.h>
   2 #include <math.h>
   3
   4 #include <GLES/gl.h>
   5 #include "SDL.h"
   6 #include "PDL.h"
   7 #include "Pixel.h"
   8 #define NPIXELS 2000
   9
  10 SDL_Surface* screen;               // Screen surface
  11 Uint16 mx, my;
  12 Pixel** pixels;
  13 GLfloat* vertices;
  14
  15 #ifdef WIN32
  16 extern "C"
  17 #endif
  18 GL_API int GL_APIENTRY _dgles_load_library(void *, void *(*)(void *, const char *));
  19
  20 static void *proc_loader(void *h, const char *name)
  21 {
  22     (void) h;
  23     return SDL_GL_GetProcAddress(name);
  24 }
  25
  26 void init() {
  27         // Set up OpenGL
  28         glClearColor(0.5f, 0.5f, 0.5f, 0.0f);
  29         glMatrixMode(GL_PROJECTION);
  30         glLoadIdentity();
  31         glOrthof(0.0f, 320.0f, 400.0f, 0.0f, -1.0f, 1.0f);
  32         glColor4f(0.0f, 0.0f, 0.0f, 1.0f);
  33
  34         // Initialize vertices
  35         vertices = new GLfloat[NPIXELS * 6];
  36         memset(vertices, 0, sizeof(GLfloat) * NPIXELS * 6);
  37         glEnableClientState(GL_VERTEX_ARRAY);
  38         glVertexPointer(3, GL_FLOAT, 0, vertices);
  39
  40         // Center cursor
  41         mx = 160;
  42         my = 200;
  43
  44         // Initialize pixel objects
  45         pixels = new Pixel*[NPIXELS];
  46         for (int x = 0; x < NPIXELS; x++) {
  47                 pixels[x] = new Pixel();
  48         }
  49
  50 }
  51
  52 void pushPixels(int pushX, int pushY) {
  53         // Apply force to each pixel outwards from the mouse
  54         for (int i = 0; i < NPIXELS; i++) {
  55                 // Get the direction
  56                 float dx = pixels[i]->x - pushX;
  57                 float dy = pixels[i]->y - pushY;
  58                 float mag = sqrtf(dx*dx + dy*dy);
  59                 dx /= mag;
  60                 dy /= mag;
  61
  62                 // Apply force.
  63                 pixels[i]->accel(dx * 10.0, dy * 10.0);
  64         }
  65 }
  66
  67 void engine() {
  68         // Clear the canvas
  69         glClear(GL_COLOR_BUFFER_BIT);
  70
  71         // Update cursor
  72         vertices[0] = mx - 5;
  73         vertices[1] = my - 5;
  74         vertices[3] = mx + 5;
  75         vertices[4] = my - 5;
  76         vertices[6] = mx + 5;
  77         vertices[7] = my + 5;
  78         vertices[9] = mx - 5;
  79         vertices[10] = my + 5;
  80         glDrawArrays(GL_LINE_LOOP, 0, 4);
  81
  82         // Update all pixel objects
  83         for (int i = 0; i < NPIXELS; i++) {
  84                 // Get distance
  85                 float dx = mx - pixels[i]->x;
  86                 float dy = my - pixels[i]->y;
  87                 float d = sqrtf(dx*dx + dy*dy);
  88
  89                 // Apply acceleration to pixels towards the mouse cursor
  90                 float ax = dx / 50.0;
  91                 float ay = dy / 50.0;
  92
  93                 // Apply a drag proportional to the distance from the cursor
  94                 if (d > 25.0) {
  95                         ax += -pixels[i]->vx * (d - 25.0) / 1000.0;
  96                         ay += -pixels[i]->vy * (d - 25.0) / 1000.0;
  97                 }
  98
  99                 // And a "chaotic" acceleration inversely proportional
 100                 // to the distance from the cursor
 101                 ax += ((rand() / (float)RAND_MAX) * 40.0 - 20.0) / d;
 102                 ay += ((rand() / (float)RAND_MAX) * 40.0 - 20.0) / d;
 103
 104                 pixels[i]->accel(ax,ay);
 105                 pixels[i]->update();
 106                 pixels[i]->draw(&vertices[i*6]);
 107         }
 108         glDrawArrays(GL_LINES, 0, NPIXELS * 2);
 109 }
 110
 111 int main(int argc, char** argv)
 112 {
 113     // Initialize the SDL library with the Video subsystem
 114     SDL_Init(SDL_INIT_VIDEO);
 115
 116     // start the PDL library
 117     PDL_Init(0);
 118
 119     // Tell it to use OpenGL ES version 1.1
 120     SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 1);
 121
 122     // Set the video mode to full screen with OpenGL-ES support
 123     screen = SDL_SetVideoMode(320, 400, 0, SDL_OPENGL);
 124     if (!screen) {
 125                 printf("Could not initialize video!\n");
 126                 exit(1);
 127     }
 128     printf("width: %d, height, %d\n", screen->w, screen->h);
 129
 130 #if WIN32
 131     // Load the desktop OpenGL-ES emulation library
 132     _dgles_load_library(NULL, proc_loader);
 133 #endif
 134
 135         init();
 136
 137     // Event descriptor
 138     SDL_Event Event;
 139         int app_is_active = 1;
 140         Uint32 last = SDL_GetTicks();
 141         int fps_counter = 0;
 142
 143     do {
 144         // Process the events
 145                 if (!app_is_active)
 146                         SDL_WaitEvent(NULL);
 147         while (SDL_PollEvent(&Event)) {
 148             switch (Event.type) {
 149                 // List of keys that have been pressed
 150                 case SDL_KEYDOWN:
 151                     switch (Event.key.keysym.sym) {
 152                         // Escape forces us to quit the app
 153                         // this is also sent when the user makes a back gesture
 154                         case SDLK_ESCAPE:
 155                             Event.type = SDL_QUIT;
 156                             break;
 157                         default:
 158                             break;
 159                     }
 160                     break;
 161                                 case SDL_MOUSEMOTION:
 162                                         mx = Event.motion.x;
 163                                         my = Event.motion.y;
 164                                         break;
 165                                 case SDL_MOUSEBUTTONDOWN:
 166                                         pushPixels(Event.button.x, Event.button.y);
 167                                 case SDL_ACTIVEEVENT:
 168                                         if (Event.active.state == SDL_APPACTIVE)
 169                                                 app_is_active = Event.active.gain;
 170                                         break;
 171                 default:
 172                     break;
 173             }
 174         }
 175
 176                 engine();
 177                 glFlush();
 178                 SDL_GL_SwapBuffers();
 179
 180                 // Calculate FPS
 181                 fps_counter++;
 182                 Uint32 now = SDL_GetTicks();
 183                 if (now - last > 1000) {
 184                         printf("%d FPS\n", fps_counter);
 185                         fps_counter = 0;
 186                         last = now;
 187                 }
 188     } while (Event.type != SDL_QUIT);
 189     // We exit anytime we get a request to quit the app
 190
 191     // Cleanup
 192     PDL_Quit();
 193     SDL_Quit();
 194
 195     return 0;
 196 }