// radar energy pattern // // compile with: gcc -o ar06 ar05.c -lgd -lpng -lm // // uses the libgd library. for documentation see the file: // /usr/share/doc/gd-*/index.html // or the website: http://www.libgd.org/reference // // you will need truetype fonts. if you don't have them, you can // copy ../fonts/truetype/.. from openoffice.org to /usr/share/ // libgd origin at upper left #define IMAGE 1 // #undef IMAGE #include "gd.h" #include "math.h" #include "string.h" #include #include #define PNGFMT "ar06.png" /* #define SCANX 1000.0 // scan width in meters #define LABX 200.0 // label spacing #define EXAG 5.0 // pixel exaggeration #define UNITS "meters" #define USCALE 1.0 #define TUNITS 1000.0 #define TSCALE "ms" #define OX0 700 // first output array left #define OX1 2000 // first output array right #define SCANX 0.1 // scan width in meters #define LABX 0.02 // label spacing #define EXAG 1.0 // pixel exaggeration #define UNITS "centimeters" #define USCALE 100.0 #define TUNITS 1000000.0 #define TSCALE "μs" #define OX0 700 // first output array left #define OX1 2000 // first output array right */ // SCANX LABX EXAG USCALE TUNITS OX0 OX1 UNITS TSCALE #define D0 "1000.0 200.0 5.0 1.0 1000.0 1200 3000 meters ms" #define D1 "0.1 0.02 1.0 100.0 1000000.0 3200 5000 centimeters μs" #define XSIZE 5120 // display window in pixels #define OY0 100 // output array top #define OY1 1200 // output array bottom #define GGAIN 250 #define GY (OY1+130+GGAIN) // plot centerline #define GT (GY+GGAIN) // time text bottom #define YSIZE (GT+20) #define EYC 1100 // earth orbit display vertical middle #define EX0 70 // earth orbit display left #define EX1 940 // earth orbit display right #define LNAR 3 // line pixel width #define LWID 5 // line pixel width #define OSLOPE -0.392 // orbit slope through field #define EINC -50.0 // inclination of target orbit #define EAOP 35.0 // argument of perigee target orbit // ------------------------------------------------------------ #define VORB 3000.0 // orbit velocity #define LAMBDA 0.005 // radio wavelength in meters #define TARGETA 400.0 // altitude of target #define TARGETN 45 // target latitude north #define S_WIDTH 200.0 // array width in meters #define S_NUM 181 // thinsats in a row, odd #define A_SPACE 12 // array spacing in degrees #define A_NUM 7 // array spacing in degrees #define NSAT (S_NUM*A_NUM) // total number of thinsats #define RE 6378.0 // earth radius kilometers #define R288 12789.0 // server sky radius kilometers #define KM 1000.0 // kilometer #define FNT "DejaVuMonoSans" #define CMAX 256 // gray scale // ========================================================================== int main() { FILE *pngout ; // file handle for png output frame char labstring[80] ; // used for labelling int icolor ; // index for computing colors int i ; // general counter int fs ; // large font size double satx[NSAT] ; // satellite x position, east positive double saty[NSAT] ; // satellite y position, out positive double satp[NSAT] ; // satellite phase in radians double sata[NSAT] ; // satellite amplitude double arrx[A_NUM] ; // array center position double arry[A_NUM] ; // array center position double pi2 = 8.0*atan(1.0) ; // 2*pi, 6.283 double d2r = pi2/360.0 ; // degrees to radians double r2d = 360.0/pi2 ; // radians to degrees // ------------------- // coordinates - z, north south, out of plane of drawing // x, orbit tangential distance from center thinsat array double targetr = (RE+TARGETA)*KM ; // target radius in meters double targetn = d2r*TARGETN ; // target latitude in radians north double targetx = 0.0 ; // target x coordinate double targety = targetr*cos(targetn); // target y coordinate double targetz = targetr*sin(targetn); // target z coordinate int idx ; // double cscale = (double) CMAX ; // // ------------------- double k = pi2/LAMBDA ; // wavenumber double re = RE * KM ; // earth radius in meters double r288 = R288 * KM ; // m288 orbit radius in meters int smid = ( S_NUM - 1 ) / 2 ; int amid = ( A_NUM - 1 ) / 2 ; double s_num = (double) S_NUM ; double a_sp = d2r* A_SPACE ; // array spacing in radians double s_sp = S_WIDTH /((S_NUM-1.0)*r288) ; // thinsat spacing rad. // ------------------- // compute position and phase of each thinsat double asum = 0.0 ; // normalize amplitude int acnt, scnt ; for( acnt=0 ; acnt < A_NUM ; acnt++ ) { double a_c = (acnt - amid)*a_sp ; // double a_0 = a_c - smid*s_sp ; // array starting angle int aidx = acnt*S_NUM ; arrx[acnt] = r288 * sin(a_c) ; arry[acnt] = r288 * cos(a_c) ; for( scnt=0 ; scnt < S_NUM ; scnt++ ) { double s_an = a_0 + scnt * s_sp ; // orbit angle for thinsat int idx = aidx + scnt ; // array index for thinsat satx[idx] = r288 * sin(s_an) ; // saty[idx] = r288 * cos(s_an) ; // double dx = satx[idx]-targetx ; // double dy = saty[idx]-targety ; // double dz = targetz ; // double d = sqrt( dx*dx + dy*dy + dz*dz ) ; // distance satp[idx] = k*d ; // phase sata[idx] = 1.0 ; // uniform amplitude for now asum += sata[idx]/d ; // summed amplitude } } double anorm = 1.0 / asum ; // set up array and define colors ----------------------------------------- gdImagePtr im = gdImageCreateTrueColor(XSIZE, YSIZE ); // allocate standard colors int black = gdImageColorAllocate(im, 0, 0, 0); int white = gdImageColorAllocate(im, 255, 255, 255); int sun1 = gdImageColorAllocate(im, 51, 51, 102); int red = gdImageColorAllocate(im, 255, 0, 0); int green = gdImageColorAllocate(im, 0, 255, 0); int dgreen= gdImageColorAllocate(im, 0, 128, 0); int blue = gdImageColorAllocate(im, 0, 0, 255); int gray = gdImageColorAllocate(im, 128, 128, 128); int dgray = gdImageColorAllocate(im, 48, 48, 48); int trans = gdImageColorAllocate(im, 1, 1, 1); int gcolor[CMAX] ; // color map numbers // allocate gray scale array for( icolor=0 ; icolor re ) || ( ez02 > 0.0 ) ) { int ex = (int)( exc + ex02 * escal ) ; int ey = (int)( eyc + ey02 * escal ) ; gdImageFilledEllipse( im, ex, ey, LWID, LWID, red ); } } // HUGE KLUDGE --------------------------------------------------------- // fake loop to change what were defines int define, OX0, OX1 ; double SCANX, LABX, EXAG, USCALE, TUNITS ; char UNITS[16], TSCALE[16]; char str[128] ; // SCANX LABX EXAG USCALE TUNITS OX0 OX1 UNITS TSCALE for( define = 0 ; define <= 1 ; define++ ) { if( define == 0 ) { strcpy( str, D0 ) ; } if( define == 1 ) { strcpy( str, D1 ) ; } sscanf( str, "%lf %lf %lf %lf %lf %d %d %s %s", &SCANX, &LABX, &EXAG, &USCALE, &TUNITS, &OX0, &OX1, UNITS, TSCALE ); printf( "\n%s\n", str ); printf( "SCANX=%9.3e ", SCANX ); printf( "LABX=%9.3e ", LABX ); printf( "EXAG=%9.3e ", EXAG ); printf( "USCALE=%9.3e\n", USCALE); printf( "TUNITS=%9.3e ", USCALE); printf( "OX0=%6d ", OX0 ); printf( "OX1=%6d ", OX1 ); printf( "UNITS=%s ", UNITS ); printf( "TSCALE=%s\n", TSCALE ); // ------------------------------------------------------------------------ // plot scaling - compute x and y from pixel value double ox0 = (double) OX0 ; // output display left double ox1 = (double) OX1 ; // output display right double oy0 = (double) OY0 ; // output display top double oy1 = (double) OY1 ; // output display bottom int ox, oy ; // output grid indices double scany = SCANX * (oy1-oy0)/(ox1-ox0); double x_d = SCANX / (ox1-ox0) ; double x_0 = targetx - ( x_d * ox0 + 0.5*SCANX ) ; double y_d = -x_d ; // pixels increase, y gets smaller double y_0 = targety - ( y_d * oy0 - 0.5*scany ) ; fs= 60 ; gdImageStringFT( im, NULL, // imagespace, bounding box black , FNT, fs, 0.0, // color, font, fontsize, angle OX0 , oy1+3*fs, // x, y UNITS ); // text // now compute pixel array double dz2 = targetz * targetz ; #ifdef IMAGE for( ox=ox0 ; ox cscale ) { mag = cscale ; } gdImageSetPixel( im, ox, oy, gcolor[mag] ) ; } } #endif // now compute path through field gdImageLine( im, OX0-10, GY, OX1+10, GY, black ); double gox = -1.0 ; double goy = -1.0 ; for( ox=ox0 ; ox