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
   9 #define NPIXELS 2500
  10 #define SCREENW 320
  11 #define SCREENH 480
  12
  13 SDL_Surface* screen;               // Screen surface
  14 Uint16 mx, my;
  15 Pixel** pixels;
  16 GLfloat* vertices;
  17
  18 #ifdef WIN32
  19 extern "C"
  20 #endif
  21 GL_API int GL_APIENTRY _dgles_load_library(void *, void *(*)(void *, const char *));
  22
  23 static void *proc_loader(void *h, const char *name)
  24 {
  25     (void) h;
  26     return SDL_GL_GetProcAddress(name);
  27 }
  28
  29 void init() {
  30         // Set up OpenGL
  31         glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
  32         glMatrixMode(GL_PROJECTION);
  33         glLoadIdentity();
  34         glOrthof(0.0f, (float)screen->w, (float)screen->h, 0.0f, -1.0f, 1.0f);
  35         glColor4f(0.0f, 0.0f, 0.0f, 1.0f);
  36
  37         // Initialize vertices
  38         vertices = new GLfloat[NPIXELS * 6];
  39         memset(vertices, 0, sizeof(GLfloat) * NPIXELS * 6);
  40         glEnableClientState(GL_VERTEX_ARRAY);
  41         glVertexPointer(3, GL_FLOAT, 0, vertices);
  42
  43         // Center cursor
  44         mx = screen->w / 2;
  45         my = screen->h / 2;
  46
  47         // Initialize pixel objects
  48         pixels = new Pixel*[NPIXELS];
  49         for (int x = 0; x < NPIXELS; x++) {
  50                 pixels[x] = new Pixel(screen);
  51         }
  52
  53 }
  54
  55 void pushPixels(int pushX, int pushY) {
  56         // Apply force to each pixel outwards from the mouse
  57         for (int i = 0; i < NPIXELS; i++) {
  58                 // Get the direction
  59                 float dx = pixels[i]->x - pushX;
  60                 float dy = pixels[i]->y - pushY;
  61                 float mag = sqrtf(dx*dx + dy*dy);
  62                 dx /= mag;
  63                 dy /= mag;
  64
  65                 // Apply force.
  66                 pixels[i]->accel(dx * 10.0, dy * 10.0);
  67         }
  68 }
  69
  70 void engine() {
  71         // Clear the canvas
  72         glClear(GL_COLOR_BUFFER_BIT);
  73
  74         // Update cursor
  75         vertices[0] = mx - 5;
  76         vertices[1] = my - 5;
  77         vertices[3] = mx + 5;
  78         vertices[4] = my - 5;
  79         vertices[6] = mx + 5;
  80         vertices[7] = my + 5;
  81         vertices[9] = mx - 5;
  82         vertices[10] = my + 5;
  83         glDrawArrays(GL_LINE_LOOP, 0, 4);
  84
  85         // Update all pixel objects
  86         for (int i = 0; i < NPIXELS; i++) {
  87                 // Get distance
  88                 float dx = mx - pixels[i]->x;
  89                 float dy = my - pixels[i]->y;
  90                 float d = sqrtf(dx*dx + dy*dy);
  91
  92                 // Apply acceleration to pixels towards the mouse cursor
  93                 float ax = dx / 50.0;
  94                 float ay = dy / 50.0;
  95
  96                 // Apply a drag proportional to the distance from the cursor
  97                 if (d > 25.0) {
  98                         ax += -pixels[i]->vx * (d - 25.0) / 1000.0;
  99                         ay += -pixels[i]->vy * (d - 25.0) / 1000.0;
 100                 }
 101
 102                 // And a "chaotic" acceleration inversely proportional
 103                 // to the distance from the cursor
 104                 ax += ((rand() / (float)RAND_MAX) * 40.0 - 20.0) / d;
 105                 ay += ((rand() / (float)RAND_MAX) * 40.0 - 20.0) / d;
 106
 107                 pixels[i]->accel(ax,ay);
 108                 pixels[i]->update();
 109                 pixels[i]->draw(&vertices[i*6]);
 110         }
 111         glDrawArrays(GL_LINES, 0, NPIXELS * 2);
 112 }
 113
 114 int main(int argc, char** argv)
 115 {
 116     // Initialize the SDL library with the Video subsystem
 117     SDL_Init(SDL_INIT_VIDEO);
 118
 119     // start the PDL library
 120     PDL_Init(0);
 121
 122     // Tell it to use OpenGL ES version 1.1
 123     SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 1);
 124
 125     // Set the video mode to full screen with OpenGL-ES support
 126     screen = SDL_SetVideoMode(SCREENW, SCREENH, 0, SDL_OPENGL);
 127     if (!screen) {
 128                 printf("Could not initialize video!\n");
 129                 exit(1);
 130     }
 131     printf("width: %d, height, %d\n", screen->w, screen->h);
 132         printf("Starting up with %d pixels\n", NPIXELS);
 133
 134 #if WIN32
 135     // Load the desktop OpenGL-ES emulation library
 136     _dgles_load_library(NULL, proc_loader);
 137 #endif
 138
 139         init();
 140
 141     // Event descriptor
 142     SDL_Event Event;
 143         int app_is_active = 1;
 144         Uint32 last = SDL_GetTicks();
 145         int fps_counter = 0;
 146
 147     do {
 148         // Process the events
 149                 if (!app_is_active)
 150                         SDL_WaitEvent(NULL);
 151         while (SDL_PollEvent(&Event)) {
 152             switch (Event.type) {
 153                                 case SDL_MOUSEMOTION:
 154                                         mx = Event.motion.x;
 155                                         my = Event.motion.y;
 156                                         break;
 157                                 case SDL_MOUSEBUTTONDOWN:
 158                                         pushPixels(Event.button.x, Event.button.y);
 159                                 case SDL_ACTIVEEVENT:
 160                                         if (Event.active.state == SDL_APPACTIVE)
 161                                                 app_is_active = Event.active.gain;
 162                                         break;
 163                 default:
 164                     break;
 165             }
 166         }
 167
 168                 engine();
 169                 glFlush();
 170                 SDL_GL_SwapBuffers();
 171
 172                 // Calculate FPS
 173                 fps_counter++;
 174                 Uint32 now = SDL_GetTicks();
 175                 if (now - last > 1000) {
 176                         printf("%d FPS\n", fps_counter);
 177                         fps_counter = 0;
 178                         last = now;
 179                 }
 180     } while (Event.type != SDL_QUIT);
 181     // We exit anytime we get a request to quit the app
 182
 183     // Cleanup
 184     PDL_Quit();
 185     SDL_Quit();
 186
 187     return 0;
 188 }