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0
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1 #include<stdio.h>
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2 #include<stdlib.h>
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3 #include<unistd.h>
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4 #include<time.h>
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5 #include<float.h>
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6 #include<SDL.h>
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7 #include<OpenGL/gl.h>
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8 #include<OpenGL/glu.h>
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9
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10 #define DEBUGlog(f, args...) \
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11 fprintf(stderr, "in %s: "f, __FUNCTION__, ## args)
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12
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13 #define W_HEIGHT 480
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14 #define W_WIDTH 640
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15
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16 /*
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17 N body problem
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18 */
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19
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20 /* parameters */
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21 static int NUM_BODY = 3;
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22 //static float Gravitation = 6.67e-11 ;
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23 //static float delta = 100;
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24 //static float FIELD = 2e11;
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1
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25 static float Gravitation = 100.0f; // ?
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26 static float delta = 0.05f; // 0.01 ~ 100 ?
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0
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27 static float FIELD = 400.0f; // -100 ~ 100
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1
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28 static const float eps = 15.0f;
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0
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29
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30 /* for OpenGL Utility. */
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31 GLUquadricObj **sphere;
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32
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33 typedef struct
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34 {
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35 /* star's parameter. */
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36 float weight;
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37 float a[3]; /* acceleration */
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38 float v[3]; /* velocity */
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39 float r[3]; /* position */
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40 /* for SDL. */
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41 //SDL_Rect rect;
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42 } body;
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43 body *stars_old, *stars_new;
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44
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45
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46 void start(void);
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47 __code initialize(int num);
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48 __code randomInit(SDL_Surface *screen, int num);
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49 __code starsInit(SDL_Surface *screen, int num);
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50 __code loop(int count, SDL_Surface *screen, int num);
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51 __code compute(int count, SDL_Surface *screen, int num);
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52 __code nextTurn(int count, SDL_Surface *screen, int num);
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53 __code moveCenter(int count, SDL_Surface *screen, int num);
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54 __code CenteringVelocity(int count, SDL_Surface *screen, int num);
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55 __code drawStars(int count, SDL_Surface *screen, int num);
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56
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57 int main(int argc, char **argv)
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58 {
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59 int ch;
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60 while ((ch = getopt(argc, argv, "s:g:")) != -1) {
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61 switch (ch) {
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62 case 's':
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63 delta = atof(optarg);
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64 break;
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65 case 'g':
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66 Gravitation = atof(optarg);
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67 break;
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68 case '?':
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69 default:
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70 break;
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71 }
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72 }
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73 start();
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74 return 0;
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75 }
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76 void start()
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77 {
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78 goto initialize(NUM_BODY);
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79 }
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80
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81 __code finish(int ret, int num)
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82 {
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83 int i;
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84 DEBUGlog("Gravity = %e\n", Gravitation);
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85 DEBUGlog("FLT_MAX = %e\n", FLT_MAX);
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86 DEBUGlog("FLT_MAX_EXP = %d\n", FLT_MAX_EXP);
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87 DEBUGlog("FLT_MIN = %e\n", FLT_MIN);
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88 DEBUGlog("FLT_MIN_EXP = %d\n", FLT_MIN_EXP);
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89 DEBUGlog("FLT_EPSILON = %e\n", FLT_EPSILON);
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90 free(stars_old);
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91 free(stars_new);
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92 for( i=0; i<NUM_BODY; i++){
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93 gluDeleteQuadric(sphere[i]);
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94 }
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95 free(sphere);
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96 exit(ret);
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97 }
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98
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99
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100 __code initialize(int num)
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101 {
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102 SDL_Surface *screen;
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103 int i;
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104
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105 /* malloc. */
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106 stars_old = malloc( sizeof(body)*num );
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107 stars_new = malloc( sizeof(body)*num );
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108 sphere = malloc( sizeof(GLUquadricObj*)*num );
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109 if (stars_old==NULL||stars_new==NULL||sphere==NULL){
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110 perror("malloc");
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111 goto finish(1, num);
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112 }
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113
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114 /* SDL initialization. */
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115 if(SDL_Init(SDL_INIT_VIDEO) < 0){ //Could we start SDL_VIDEO?
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116 fprintf(stderr,"Couldn't init SDL"); //Nope, output to stderr and quit
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117 exit(1);
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118 }
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119 SDL_GL_SetAttribute( SDL_GL_RED_SIZE, 5);
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120 SDL_GL_SetAttribute( SDL_GL_GREEN_SIZE, 5);
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121 SDL_GL_SetAttribute( SDL_GL_BLUE_SIZE, 5);
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122 SDL_GL_SetAttribute( SDL_GL_DEPTH_SIZE, 16);
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123 SDL_GL_SetAttribute( SDL_GL_DOUBLEBUFFER, 1);
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124
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125 screen = SDL_SetVideoMode(W_WIDTH, W_HEIGHT, 32, SDL_HWSURFACE | SDL_RESIZABLE | SDL_OPENGL ); //Create a 640x480x32 resizable window
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126 atexit(SDL_Quit); //Now that we're enabled, make sure we cleanup
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127
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128 /* initialize OpenGL. */
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129 glViewport(0,0,screen->w,screen->h);
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130 glMatrixMode(GL_PROJECTION);
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131 glLoadIdentity();
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132 gluPerspective( 60.0, (float)screen->w/(float)screen->h, 1.0, 1000.0);
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1
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133 gluLookAt( 300.0,300.0,300.0, 0.0,0.0,0.0, 1.0,0.0,0.0);
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0
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134 glClearColor(0.0, 0.0, 0.0, 0.0);
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135 glMatrixMode(GL_MODELVIEW);
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136
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137 //DEBUGlog("scr->w=%d\n", screen->w);
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138 //DEBUGlog("scr->h=%d\n", screen->h);
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139 for( i=0; i<num; i++){
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140 sphere[i] = gluNewQuadric();
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141 gluQuadricDrawStyle(sphere[i], GLU_FILL);
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142 }
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143
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144 goto starsInit(screen, num);
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145 }
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146
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1
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147 __code starsInitRandom(SDL_Surface *screen, int num)
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0
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148 {
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149 int i;
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150 srandom(time(NULL));
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151 for (i=0; i<num; i++){ // this loop should be split into few code segment..
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152 stars_old[i].weight = random()/(RAND_MAX+1.0)*5+5;
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153 stars_old[i].v[0] = random()/(RAND_MAX+1.0)*5+5;
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154 stars_old[i].v[1] = random()/(RAND_MAX+1.0)*5+5;
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155 stars_old[i].v[2] = random()/(RAND_MAX+1.0)*5+5;
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156 stars_old[i].r[0] = random()/(RAND_MAX+1.0)*5+5;
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157 stars_old[i].r[1] = random()/(RAND_MAX+1.0)*5+5;
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158 stars_old[i].r[2] = random()/(RAND_MAX+1.0)*5+5;
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159 stars_new[i].weight = stars_old[i].weight;
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160 }
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161
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162 goto loop(0, screen, num);
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163 }
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164 __code starsInit(SDL_Surface *screen, int num)
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165 {
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166 int i;
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167 /* */
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1
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168 stars_old[0].weight = 1000;
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0
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169 stars_old[0].v[0] = 0.0;
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170 stars_old[0].v[1] = 0.0;
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171 stars_old[0].v[2] = 0.0;
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172 stars_old[0].r[0] = 0.0;
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173 stars_old[0].r[1] = 0.0;
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174 stars_old[0].r[2] = 0.0;
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1
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175 /* */
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176 stars_old[1].weight = 5;
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177 stars_old[1].v[0] = 0.1;
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178 stars_old[1].v[1] = 5.0;
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0
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179 stars_old[1].v[2] = 0.0;
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1
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180 stars_old[1].r[0] = 100.0;
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0
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181 stars_old[1].r[1] = 0.0;
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182 stars_old[1].r[2] = 0.0;
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1
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183 /* */
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184 stars_old[2].weight = 5;
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0
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185 stars_old[2].v[0] = 0.0;
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1
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186 stars_old[2].v[1] = -5.0;
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187 stars_old[2].v[2] = 0.1;
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188 stars_old[2].r[0] = -100.0;
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0
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189 stars_old[2].r[1] = 0.0;
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190 stars_old[2].r[2] = 0.0;
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191
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192 for( i=0; i<num; i++){
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193 stars_new[i].weight = stars_old[i].weight;
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194 //stars_new[i].rect.h = 5, stars_new[i].rect.w = 5;
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195 //stars_old[i].rect.h = 5, stars_old[i].rect.w = 5;
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196 }
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197
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198 goto loop(0, screen, num);
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199 }
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200
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201 __code loop(int count, SDL_Surface *screen, int num)
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202 {
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203 SDL_Event event;
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204
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205 /* check SDL event. */
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206 while(SDL_PollEvent(&event)){ //Poll events
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207 switch(event.type){ //Check event type
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208 case SDL_QUIT: //User hit the X (or equivelent)
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209 goto finish(1, num);
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210 //case SDL_VIDEORESIZE: //User resized window
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211 //screen = SDL_SetVideoMode(event.resize.w, event.resize.h, 32,
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212 //SDL_HWSURFACE | SDL_RESIZABLE); // Create new window
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213 //break; //Event handled, fetch next :)
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214 case SDL_KEYDOWN:
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215 if (event.key.keysym.sym==SDLK_UP && event.key.state==SDL_PRESSED)
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216 FIELD *= 2.0;
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217 else if (event.key.keysym.sym==SDLK_DOWN && event.key.state==SDL_PRESSED)
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218 FIELD /= 2.0;
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219 else if (event.key.keysym.sym==SDLK_r && event.key.state==SDL_PRESSED)
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220 goto moveCenter(count, screen, num);
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221 else if (event.key.keysym.sym==SDLK_v && event.key.state==SDL_PRESSED)
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222 goto CenteringVelocity(count, screen, num);
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223 else if (event.key.keysym.sym==SDLK_l && event.key.state==SDL_PRESSED)
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224 goto AdjustLook(count, screen, num);
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225 break;
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226 default:
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227 break;
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228 } //Finished with current event
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229 } //Done with all events for now
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230
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231 if ( count<num ){
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232 DEBUGlog("count %d, goto commpute().\n", count);
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233 goto compute(count, screen, num);
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234 }else{
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235 DEBUGlog("count %d, goto nextTurn()\n", count);
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236 goto nextTurn(count, screen, num);
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237 }
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238 }
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239
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240 __code AdjustLook(int count, SDL_Surface *screen, int num)
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241 {
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242 int i;
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243 float c0,c1,c2;
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244 float v0,v1,v2,v;
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245 c0=c1=c2=v0=v1=v2=0;
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246
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247 for (i=0; i<num; i++){
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248 c0 += stars_new[i].r[0];
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249 c1 += stars_new[i].r[1];
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250 c2 += stars_new[i].r[2];
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251 }
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252 c0/=3.0; c1/=3.0; c2/=3.0;
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253 for (i=0; i<num; i++){
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254 v0 += (stars_new[i].r[0]-c0)*(stars_new[i].r[0]-c0);
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255 v1 += (stars_new[i].r[1]-c1)*(stars_new[i].r[1]-c1);
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256 v2 += (stars_new[i].r[2]-c2)*(stars_new[i].r[2]-c2);
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257 }
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258 v = v0+v1+v2;
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259 v0 = sqrt(v0); v1 = sqrt(v1); v2 = sqrt(v2);
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260 v = sqrt(v);
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261
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262 glMatrixMode(GL_PROJECTION);
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263 glLoadIdentity();
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264 gluPerspective( 60.0, (float)screen->w/(float)screen->h, 1.0, v);
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265 gluLookAt( v,v,v, 0.0,0.0,0.0, 1.0,0.0,0.0);
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266 glClearColor(0.0, 0.0, 0.0, 0.0);
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267 glMatrixMode(GL_MODELVIEW);
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268
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269 goto loop(0, screen, num);
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270 }
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271
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272 __code CenteringVelocity(int count, SDL_Surface *screen, int num)
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273 {
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274 int i;
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275 float v0,v1,v2;
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276 v0=v1=v2=0.0;
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277
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278 for (i=0; i<num; i++){
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279 v0 += stars_old[i].v[0];
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280 v1 += stars_old[i].v[1];
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281 v2 += stars_old[i].v[2];
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282 }
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283 v0/=(float)num; v1/=(float)num; v2/=(float)num;
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284 for (i=0; i<num; i++){
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285 stars_old[i].v[0] -= v0;
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286 stars_old[i].v[1] -= v1;
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287 stars_old[i].v[2] -= v2;
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288 }
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289
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290 goto loop(0, screen, num);
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291 }
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292 __code moveCenter(int count, SDL_Surface *screen, int num)
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293 {
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294 int i;
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295 float m0,m1,m2;
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296 m0=m1=m2=0.0;
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297
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298 for (i=0; i<num; i++){
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299 m0 += stars_old[i].r[0];
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300 m1 += stars_old[i].r[1];
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301 m2 += stars_old[i].r[2];
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302 }
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303 m0/=(float)num; m1/=(float)num; m2/=(float)num;
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304 for (i=0; i<num; i++){
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305 stars_old[i].r[0] -= m0;
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306 stars_old[i].r[1] -= m1;
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307 stars_old[i].r[2] -= m2;
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308 }
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309
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310 goto loop(0, screen, num);
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311 }
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312
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313 /*
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314 * next x = x+dx
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315 * dx = v*dt => dx/dt = v
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316 * dv = a*dt => dv/dt = a
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317 * a = F/m;
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318 * F = F1 + F2 + ... + Fn
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319 * Fi = G m1m2/r^2
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320 *
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321 */
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322 __code compute(int count, SDL_Surface *screen, int num)
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323 {
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324 int i;
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325 /* a is accel this planet receive now. */
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326 stars_old[count].a[0]=stars_old[count].a[1]=stars_old[count].a[2]=0.0f;
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327 DEBUGlog("count=%d\n", count);
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328 for (i=0; i<num; i++){ // this loop should be split into few code segment..
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329 //float F;
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330 float d0, d1, d2, d;
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331 float a;
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332 //body *o, *m;
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333 //o = &stars_old[i]; m = &stars_old[count];
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334
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335 /* skip compute with itself. */
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336 if ( i==count ) continue;
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337 /* compute distance between two i-th planet and itself. */
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338 d0 = stars_old[i].r[0] - stars_old[count].r[0];
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339 d1 = stars_old[i].r[1] - stars_old[count].r[1];
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340 d2 = stars_old[i].r[2] - stars_old[count].r[2];
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1
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341 d = ( d0*d0+d1*d1+d2*d2+eps*eps );
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0
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342 /* compute force it receive from i-th planet. */
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343 //F = Gravitation * stars_old[i].weight * stars_old[count].weight / d;
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344 /* and accel. */
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345 //a = F/stars_old[count].weight;
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346 a = Gravitation/d * stars_old[i].weight ;
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347 stars_old[count].a[0] += a*d0/sqrt(d);
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348 stars_old[count].a[1] += a*d1/sqrt(d);
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349 stars_old[count].a[2] += a*d2/sqrt(d);
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350 DEBUGlog("a=%e, d=%e, d0=%e\n", a, d, d0);
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351 DEBUGlog("g*w=%e\n", Gravitation*stars_old[i].weight);
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352 }
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353
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354 stars_new[count].v[0] = stars_old[count].v[0]+stars_old[count].a[0]*delta;
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355 stars_new[count].v[1] = stars_old[count].v[1]+stars_old[count].a[1]*delta;
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356 stars_new[count].v[2] = stars_old[count].v[2]+stars_old[count].a[2]*delta;
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357 stars_new[count].r[0] = stars_old[count].r[0]+stars_new[count].v[0]*delta/*+stars_old[count].a[0]*delta*delta/2.0*/;
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358 stars_new[count].r[1] = stars_old[count].r[1]+stars_new[count].v[1]*delta/*+stars_old[count].a[1]*delta*delta/2.0*/;
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359 stars_new[count].r[2] = stars_old[count].r[2]+stars_new[count].v[2]*delta/*+stars_old[count].a[2]*delta*delta/2.0*/;
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360
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361 DEBUGlog("x = %e\n", stars_new[count].r[0]);
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362 DEBUGlog("y = %e\n", stars_new[count].r[1]);
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363 DEBUGlog("z = %e\n", stars_new[count].r[2]);
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364 DEBUGlog("vx = %e\n", stars_new[count].v[0]);
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365 DEBUGlog("vy = %e\n", stars_new[count].v[1]);
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366 DEBUGlog("vz = %e\n", stars_new[count].v[2]);
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367 DEBUGlog("a0=%e,a1=%e,a2=%e\n", stars_new[count].a[0], stars_new[count].a[1], stars_new[count].a[2]);
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368
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369 goto loop(++count, screen, num);
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370 }
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371
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372 /* it is executed after all bodies parameter is computed. */
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373 __code nextTurn(int count, SDL_Surface *screen, int num)
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374 {
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375 body *tmp;
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376 tmp = stars_old;
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377 stars_old = stars_new;
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378 stars_new = tmp;
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379 SDL_UpdateRect(screen, 0, 0, 0, 0);
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380
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381 goto drawStars(count, screen, num);
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382 }
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383
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384 __code drawStars(int count, SDL_Surface *screen, int num)
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385 {
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386 int i;
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387 DEBUGlog("draw\n");
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388 glClear( GL_COLOR_BUFFER_BIT );
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389 for (i=0; i<num; i++){
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390 glPushMatrix();
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391 glTranslatef( stars_new[i].r[0], stars_new[i].r[1], stars_new[i].r[2]);
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1
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392 gluSphere( sphere[i], 2.0, 8.0, 8.0 );
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0
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393 glPopMatrix();
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394 }
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395
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396 glColor3d( 1.0, 1.0, 1.0);
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397 glBegin(GL_LINES);
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398 glVertex3d( 0.0, 0.0, 0.0);
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399 glVertex3d( 10.0, 0.0, 0.0);
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400 glEnd();
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401 glBegin(GL_LINES);
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402 glVertex3d( 0.0, 0.0, 0.0);
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403 glVertex3d( 0.0, 10.0, 0.0);
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404 glEnd();
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405 glBegin(GL_LINES);
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406 glVertex3d( 0.0, 0.0, 0.0);
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407 glVertex3d( 0.0, 0.0, 10.0);
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|
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408 glEnd();
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409
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|
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410 SDL_GL_SwapBuffers();
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|
|
411 goto loop(0, screen, num);
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|
|
412 }
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|
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413
|
