dethphysics/vector.c

   1 //headers
   2 #include <SDL/SDL.h>
   3 #include <SDL/SDL_opengl.h>
   4 #include <stdio.h>
   5 #include <math.h>
   6
   7 //Screen attributes
   8 const int SCREEN_WIDTH = 640;
   9 const int SCREEN_HEIGHT = 480;
  10 const int SCREEN_BPP = 32;
  11
  12 //function prototypes
  13 void draw_line(int, int, int, int vectores[][2]);
  14 void draw_axis();
  15 void draw_vectors(int, int vectores[][2]);
  16 void dibuja_flecha(int, int);
  17
  18 int main(int argc, char *argv[])
  19 {
  20     int quit = 0;
  21
  22     //Initialize
  23     if( init() == 0 )
  24     {
  25         return 1;
  26     }
  27
  28     SDL_Surface *screen;
  29     SDL_Event event; //The event structure
  30     int cantidad = 0; // cantidad de vectores
  31     int vectores[1000][2]; //arreglo de vectores
  32
  33     glBegin(GL_LINES);
  34     draw_axis();
  35     glEnd();
  36
  37     //escucha de eventos
  38     //While the user hasn't quit
  39     while( quit == 0 )
  40     {
  41
  42         //If there's events to handle
  43         if( SDL_PollEvent( &event ) )
  44         {
  45             //reset the viewport
  46            // glViewport(0, 0, 600, 800);
  47
  48             //The mouse offsets
  49             int x = 0, y = 0;
  50
  51             //If the mouse moved
  52             if( event.type == SDL_MOUSEMOTION )
  53             {
  54                 //Get the mouse offsets
  55                 x = event.motion.x;
  56                 y = event.motion.y;
  57                 draw_line(x, y, cantidad, vectores);
  58             }
  59
  60             if (event.type == SDL_MOUSEBUTTONDOWN)
  61             {
  62                 if( event.button.button == SDL_BUTTON_LEFT )
  63                 {
  64                    vectores[cantidad][0] = event.button.x;
  65                    vectores[cantidad][1] = event.button.y;
  66                    cantidad++;
  67                 }
  68             }
  69
  70             SDL_GL_SwapBuffers();
  71             //If the user has Xed out the window
  72             if( event.type == SDL_QUIT )
  73             {
  74                 //Quit the program
  75                 quit = 1;
  76             }
  77         }
  78     }
  79
  80     SDL_Quit();
  81
  82     return 0;
  83 }
  84
  85 int init_GL()
  86 {
  87     //Set clear color
  88     glClearColor( 0, 0, 0, 0 );
  89
  90     //Set the viewport
  91     glViewport(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT);
  92
  93     //Set projection
  94     glMatrixMode( GL_PROJECTION );
  95     glLoadIdentity();
  96     glOrtho( 0, SCREEN_WIDTH, SCREEN_HEIGHT, 0, -1, 1 );
  97
  98     //Initialize modelview matrix
  99     glMatrixMode( GL_MODELVIEW );
 100     glLoadIdentity();
 101
 102     //If there was any errors
 103     if( glGetError() != GL_NO_ERROR )
 104     {
 105         return 0;
 106     }
 107
 108     //If everything initialized
 109     return 1;
 110 }
 111
 112 int init()
 113 {
 114     //Initialize SDL
 115     if( SDL_Init( SDL_INIT_EVERYTHING ) < 0 )
 116     {
 117         return 0;
 118     }
 119
 120     //Create Window
 121     if( SDL_SetVideoMode( SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP, SDL_OPENGL ) == NULL )
 122     {
 123         return 0;
 124     }
 125
 126     //Initialize OpenGL
 127     if( init_GL() == 0 )
 128     {
 129         return 0;
 130     }
 131
 132     //Set caption
 133     SDL_WM_SetCaption( "OpenGL Test", NULL );
 134
 135     return 1;
 136 }
 137
 138 void draw_line(int x, int y, int cantidad, int vectores [][2])
 139 {
 140     // Clear the screen before drawing:
 141     glClear( GL_COLOR_BUFFER_BIT );
 142
 143     // draw the line
 144     glBegin(GL_LINES);
 145
 146         draw_axis();
 147         draw_vectors(cantidad, vectores);
 148
 149         //dibuja lineas
 150         glVertex3f( SCREEN_WIDTH/2, SCREEN_HEIGHT/2, 0 );
 151         glVertex3f( x, y, 0 );
 152         dibuja_flecha(x,y);
 153
 154     glEnd();
 155 }
 156
 157 void draw_vectors(int cantidad, int vectores[][2])
 158 {
 159      int i=0;
 160      while(i < cantidad && (cantidad != 0))
 161      {
 162          glVertex3f( SCREEN_WIDTH/2, SCREEN_HEIGHT/2, 0 );
 163          glVertex3f( vectores[i][0], vectores[i][1], 0 );
 164          i++;
 165      }
 166 }
 167
 168 void draw_axis()
 169 {
 170         //eje x
 171         glVertex3f( SCREEN_WIDTH/2, 20, 0 );
 172         glVertex3f( SCREEN_WIDTH/2,SCREEN_HEIGHT - 20, 0 );
 173         //eje y
 174         glVertex3f( SCREEN_WIDTH - 20, SCREEN_HEIGHT/2, 0 );
 175         glVertex3f( 20, SCREEN_HEIGHT/2,0 );
 176 }
 177
 178 void dibuja_flecha(int x1, int y1){
 179         int x = x1 - SCREEN_WIDTH/2;
 180         int y = y1 - SCREEN_HEIGHT/2;
 181         float theta = atan2(y, x); //angulo del vector
 182         int magnitud = 20;//magnitud del vector
 183         float a1=0, b1 = 0; //
 184         float a2=0, b2 = 0;
 185
 186         //valores del vector flecha
 187         //obtengo los angulos
 188         float phi1 = theta + 210;
 189         float phi2 = theta - 210;
 190
 191         //obtengo los puntos y le sumo el valor del punto P(x1,y1)
 192         //para obtener una representacion particular
 193         a1 = magnitud*cos( phi1 ) + x1; b1 = magnitud*sin( phi1 ) + y1;
 194         a2 = magnitud*cos( phi2 ) + x1; b2 = magnitud*sin( phi2 ) + y1;
 195
 196        //dibuja la lineas de la flecha
 197        glVertex3f ( x1, y1, 0);
 198        glVertex3f ( a1, b1, 0);
 199        glVertex3f ( x1, y1, 0);
 200        glVertex3f ( a2, b2, 0);
 201 }