dethphysics/vector3D.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     glRotatef(15, 1.0, 0.0, 0.0);
  33     glRotatef(-25, 0.0, 1.0, 0.0);
  34     glBegin(GL_LINES);
  35     draw_axis();
  36     glEnd();
  37     //escucha de eventos
  38     //While the user hasn't quit
  39     while( quit == 0 )
  40     {
  41         //If there's events to handle
  42         if( SDL_PollEvent( &event ) )
  43         {
  44             //The mouse offsets
  45             int x = 0, y = 0;
  46
  47             //If the mouse moved
  48             if( event.type == SDL_MOUSEMOTION )
  49             {
  50                 //Get the mouse offsets
  51                 x = event.motion.x;
  52                 y = event.motion.y;
  53                 x = x - SCREEN_WIDTH/2;
  54                 y = SCREEN_HEIGHT/2 - y;
  55                 draw_line(x, y, cantidad, vectores);
  56             }
  57
  58             if (event.type == SDL_MOUSEBUTTONDOWN)
  59             {
  60                 if( event.button.button == SDL_BUTTON_LEFT )
  61                 {
  62                    vectores[cantidad][0] = event.button.x;
  63                    vectores[cantidad][1] = event.button.y;
  64                    cantidad++;
  65                 }
  66             }
  67             SDL_GL_SwapBuffers();
  68             //If the user has Xed out the window
  69             if( event.type == SDL_QUIT )
  70             {
  71                 //Quit the program
  72                 quit = 1;
  73             }
  74         }
  75     }
  76
  77     SDL_Quit();
  78
  79     return 0;
  80 }
  81
  82 int init_GL()
  83 {
  84     //Set clear color
  85     glClearColor( 0, 0, 0, 0 );
  86
  87     //reset the viewport
  88     glViewport(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT);
  89
  90     //Set projection
  91     glMatrixMode( GL_PROJECTION );
  92     glLoadIdentity();
  93     gluPerspective(45.0f,(GLfloat) SCREEN_WIDTH/(GLfloat)SCREEN_HEIGHT, 0.1f, 1000.0f);
  94     //Initialize modelview matrix
  95     glMatrixMode( GL_MODELVIEW );
  96     glLoadIdentity();
  97
  98     glTranslatef( 0.0f, 0.0f, -500.0f );
  99     //If there was any errors
 100     if( glGetError() != GL_NO_ERROR )
 101     {
 102         return 0;
 103     }
 104
 105     //If everything initialized
 106     return 1;
 107 }
 108
 109 int init()
 110 {
 111     //Initialize SDL
 112     if( SDL_Init( SDL_INIT_EVERYTHING ) < 0 )
 113     {
 114         return 0;
 115     }
 116
 117     //Create Window
 118     if( SDL_SetVideoMode( SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP, SDL_OPENGL ) == NULL )
 119     {
 120         return 0;
 121     }
 122
 123     //Initialize OpenGL
 124     if( init_GL() == 0 )
 125     {
 126         return 0;
 127     }
 128
 129     //Set caption
 130     SDL_WM_SetCaption( "OpenGL Test", NULL );
 131
 132     return 1;
 133 }
 134
 135 void draw_line(int x, int y, int cantidad, int vectores [][2])
 136 {
 137     // Clear the screen before drawing:
 138     glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT  );
 139
 140     // draw the line
 141     glBegin(GL_LINES);
 142
 143         draw_axis();
 144         draw_vectors(cantidad, vectores);
 145
 146         //dibuja lineas
 147         glVertex3f( 0, 0, 0 );
 148         glVertex3f( x, 0, -1*y );
 149         dibuja_flecha(x,y);
 150
 151     glEnd();
 152 }
 153
 154 void draw_vectors(int cantidad, int vectores[][2])
 155 {
 156      int i=0;
 157      while(i < cantidad && (cantidad != 0))
 158      {
 159          glVertex3f( 0, 0, 0 );
 160          glVertex3f( vectores[i][0], vectores[i][1], 0 );
 161          i++;
 162      }
 163 }
 164
 165 void draw_axis()
 166 {
 167         //eje x
 168         glVertex3f( SCREEN_WIDTH/2 - 100, 0, 0 );
 169         glVertex3f( -1*SCREEN_WIDTH/2 + 50, 0, 0 );
 170
 171         //eje y
 172         glVertex3f( 0, SCREEN_HEIGHT/2 - 60 , 0 );
 173         glVertex3f( 0, -1*SCREEN_HEIGHT/2 + 30,0 );
 174
 175         //eje z
 176          glVertex3f( 0, 0, SCREEN_HEIGHT/2 - 50);
 177          glVertex3f( 0, 0, -2*SCREEN_HEIGHT/2 );
 178
 179 }
 180
 181 void dibuja_flecha(int x1, int y1){
 182         int x = x1;
 183         int y = y1;
 184         float theta = atan2(y, x); //angulo del vector
 185         int magnitud = 20;//magnitud del vector
 186         float a1=0, b1 = 0; //
 187         float a2=0, b2 = 0;
 188
 189         //valores del vector flecha
 190         //obtengo los angulos
 191         float phi1 = theta + 210;
 192         float phi2 = theta - 210;
 193
 194         //obtengo los puntos y le sumo el valor del punto P(x1,y1)
 195         //para obtener una representacion particular
 196         a1 = magnitud*cos( phi1 ) + x1; b1 = magnitud*sin( phi1 ) + y1;
 197         a2 = magnitud*cos( phi2 ) + x1; b2 = magnitud*sin( phi2 ) + y1;
 198
 199        //dibuja la lineas de la flecha
 200        glVertex3f ( x1, 0, -y1);
 201        glVertex3f ( a1, 0, -b1);
 202        glVertex3f ( x1, 0, -y1);
 203        glVertex3f ( a2, 0, -b2);
 204 }