course/semester2/pprog/assignment0/graphics.c

   1 /**
   2  * @file graphics.c
   3  * @purpose Wrapper for SDL and OpenGL graphics libraries. Used for N-Body simulator. Implementations. Mostly copied from internet tutorials.
   4  * @author Sam Moore
   5  * @date August 2012
   6  */
   7
   8
   9
  10 #include "graphics.h"
  11
  12 #include <math.h> //For trig functions
  13
  14 static int screen_width = 0;
  15 static int screen_height = 0;
  16
  17 /**
  18  * @function Graphics_Init
  19  * @purpose Initialise the SDL/OpenGL graphics system
  20  * @param caption - The caption to give the view window
  21  * @param w - The width of the view window
  22  * @param h - The height of the view window
  23  */
  24 void Graphics_Init(const char * caption, int w, int h)
  25 {
  26         if (SDL_Init(SDL_INIT_VIDEO) != 0)
  27         {
  28                 fprintf(stderr, "Graphics_Init - Couldn't initialise SDL! SDL_GetError() = %s\n",SDL_GetError());
  29                 exit(EXIT_FAILURE);
  30         }
  31
  32         SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
  33
  34         SDL_Surface * screen = SDL_SetVideoMode(w,h, 32, SDL_OPENGL);
  35         if ( screen == NULL )
  36         {
  37                 fprintf(stderr, "Graphics_Init - Couldn't set SDL VideoMode (%d x %d x 32). SDL_GetError() = %s\n", w, h, SDL_GetError());
  38                 exit(EXIT_FAILURE);
  39         }
  40
  41         glEnable(GL_TEXTURE_2D);
  42         glClearColor(0,0,0,0);
  43         glViewport(0,0,w,h);    //DOES matter
  44         glClear(GL_COLOR_BUFFER_BIT);
  45         glMatrixMode(GL_PROJECTION);
  46         glLoadIdentity();
  47         glOrtho(0,w,h,0,-1,1);
  48         glMatrixMode(GL_MODELVIEW);
  49         glLoadIdentity();
  50         glDisable(GL_DEPTH_TEST);
  51         SDL_WM_SetCaption(caption, NULL);
  52
  53
  54         screen_width = w; screen_height = h;
  55
  56         atexit(Graphics_Destroy);
  57 }
  58
  59 /**
  60  * @function Graphics_Destroy
  61  * @purpose Destroy the Graphics system
  62  *              Note: Just wrap to SDL_Quit for now
  63  */
  64 void Graphics_Destroy()
  65 {
  66         SDL_Quit();
  67 }
  68
  69 /**
  70  * @function Graphics_DrawPixel
  71  * @purpose Draw a pixel
  72  * @param x[...] Position of pixel
  73  * @param r - Red component (0-1)
  74  * @param g - Green component (0-1)
  75  * @param b - Blue component (0-1)
  76  */
  77 void Graphics_Pixel(int x[DIMENSIONS], float r, float g, float b)
  78 {
  79         glBegin(GL_POINTS);
  80         glColor3f(r, g, b);
  81         if (DIMENSIONS == 2)
  82                 glVertex2f(x[0], x[1]);
  83         else if (DIMENSIONS == 3)
  84                 glVertex3f(x[0], x[1], x[2]);
  85         else
  86         {
  87                 fprintf(stderr, "Graphics_DrawPixel - DIMENSIONS = %d, expected 2 or 3\n", DIMENSIONS);
  88                 exit(EXIT_FAILURE);
  89         }
  90
  91         glColor3f(1,1,1);
  92         glEnd();
  93 }
  94
  95 /**
  96  * @function Graphics_DrawLine
  97  * @purpose Draw a straight line between two points
  98  * @param x1[...] - First coordinate
  99  * @param x2[...] - Second coordinate
 100  * @param r - Red component (0-1)
 101  * @param g - Green component (0-1)
 102  * @param b - Blue component (0-1)
 103  */
 104 void Graphics_Line(int x1[DIMENSIONS], int x2[DIMENSIONS], float r, float g, float b)
 105 {
 106
 107         glColor3f(r, g, b);
 108         glBegin(GL_LINES);
 109         if (DIMENSIONS == 2)
 110         {
 111                 glVertex2f(x1[0], x1[1]); // origin of the line
 112                 glVertex2f(x2[0], x2[1]); // ending point of the line
 113         }
 114         else if (DIMENSIONS == 3)
 115         {
 116                 glVertex3f(x1[0], x1[1], x1[2]); // origin of the line
 117                 glVertex3f(x2[0], x2[1], x2[2]); // ending point of the line
 118         }
 119         else
 120         {
 121                 fprintf(stderr, "Graphics_DrawLine - DIMENSIONS = %d, expected 2 or 3\n", DIMENSIONS);
 122                 exit(EXIT_FAILURE);
 123         }
 124         glColor3f(1,1,1);
 125         glEnd();
 126
 127
 128 }
 129
 130 /**
 131  * @function Graphics_Circle
 132  * @purpose Draw a 2D Circle (filled)
 133  * @param x[...] Position to draw at
 134  * @param radius - Radius of circle
 135  * @param r - Red component (0-1)
 136  * @param g - Green component (0-1)
 137  * @param b - Blue component (0-1)
 138  */
 139
 140 void Graphics_Circle(int x[2], float radius, float r, float g, float b)
 141 {
 142         glColor3f(r, g, b);
 143
 144         glBegin(GL_TRIANGLE_FAN);
 145         glVertex2f(x[0], x[1]);
 146         for (float angle = 0; angle < 360; angle+=1)
 147         {
 148                 glVertex2f(x[0] + sin(angle) * radius, x[1] + cos(angle) * radius);
 149         }
 150         glColor3f(1, 1, 1);
 151         glEnd();
 152 }
 153
 154 /**
 155  * @function Graphics_Clear
 156  * @purpose Clear the screen
 157  * @param r - Red component of clear colour
 158  * @param g - Green component
 159  * @param b - Blue component
 160  */
 161 void Graphics_Clear(float r, float g, float b)
 162 {
 163         glClearColor(r,g,b,1);
 164         glClear(GL_COLOR_BUFFER_BIT);
 165 }
 166
 167 /**
 168  * @function Graphics_Update
 169  * @purpose Update the screen
 170  */
 171 void Graphics_Update()
 172 {
 173         SDL_GL_SwapBuffers();
 174         //SDL_Flip(screen);
 175 }
 176
 177 /**
 178  * @function Process_Events
 179  * @purpose Handle any SDL events recieved.
 180  */
 181 void Process_Events()
 182 {
 183         static float view_v[3] = {0,0,0};
 184         static float view_speed = 5.0;
 185         static float view_scale = 1;
 186         SDL_Event event;
 187
 188
 189
 190
 191         while (SDL_PollEvent(&event))
 192         {
 193                 switch (event.type)
 194                 {
 195                         case SDL_KEYDOWN:
 196                                 switch (event.key.keysym.sym)
 197                                 {
 198                                         case SDLK_LEFT:
 199                                                 view_v[0] += view_speed;
 200                                                 break;
 201                                         case SDLK_RIGHT:
 202                                                 view_v[0] -= view_speed;
 203                                                 break;
 204                                         case SDLK_UP:
 205                                                 view_v[1] += view_speed;
 206                                                 break;
 207                                         case SDLK_DOWN:
 208                                                 view_v[1] -= view_speed;
 209                                                 break;
 210                                         case SDLK_i:
 211                                                 view_v[0] = 0; view_v[1] = 0; view_v[2] = 0;
 212                                                 view_scale = 1;
 213                                                 glLoadIdentity();
 214                                                 break;
 215                                         default:
 216                                                 break;
 217                                 }
 218                                 break;
 219                         case SDL_KEYUP:
 220                                 switch (event.key.keysym.sym)
 221                                 {
 222                                         case SDLK_LEFT:
 223                                         case SDLK_RIGHT:
 224                                                 view_v[0] = 0;
 225                                                 break;
 226                                         case SDLK_UP:
 227                                         case SDLK_DOWN:
 228                                                 view_v[1] = 0;
 229                                         default:
 230                                                 break;
 231                                 }
 232                                 break;
 233
 234                         case SDL_MOUSEBUTTONDOWN:
 235                         {
 236                                 int mouse[2];
 237                                 SDL_GetMouseState(mouse, mouse+1);
 238
 239                                 switch (event.button.button)
 240                                 {
 241                                         case SDL_BUTTON_WHEELUP:
 242
 243                                                 view_scale = 1.05;
 244                                                 glTranslatef(screen_width/2.0, screen_height/2.0,0.0);
 245                                                 glScaled(view_scale, view_scale, 1);
 246                                                 glTranslatef(-screen_width/2.0, -screen_height/2.0, 0.0);
 247                                                 break;
 248                                         case SDL_BUTTON_WHEELDOWN:
 249                                                 view_scale = 0.95;
 250                                                 glTranslatef(screen_width/2.0, screen_height/2.0,0.0);
 251                                                 glScaled(view_scale, view_scale, 1);
 252                                                 glTranslatef(-screen_width/2.0, -screen_height/2.0, 0.0);
 253                                                 break;
 254                                         default:
 255                                                 break;
 256
 257                                 }
 258
 259                                 break;
 260                         }
 261                         case SDL_MOUSEBUTTONUP:
 262                                 break;
 263                         case SDL_QUIT:
 264                                 exit(EXIT_SUCCESS);
 265                                 break;
 266                 }
 267         }
 268
 269
 270         glTranslatef(view_v[0], view_v[1], view_v[2]);
 271         //SDL_Delay(1);
 272 }
 273