main.cpp

00001 /* Mandelbrot for mbed - April 2013
00002  * Uses Peter Drescher's library for Mikroelektronika's TFT-Proto screen, an inexpensive SPI-driven QVGA touch panel
00003  * Library: http://mbed.org/cookbook/SPI-driven-QVGA-TFT
00004  * Manufacturer's page for the screen: http://www.mikroe.com/add-on-boards/display/tft-proto/
00005  * UK distributor: http://www.mcustore.com/tft-proto-board.html
00006  * Partly adapted from Kamil Ondrousek's code for another screen: http://mbed.org/users/JLS/code/Mandelbrot-2/
00007  */
00008 #include "mbed.h"
00009 #include "SPI_TFT.h"
00010 #include "Arial12x12.h"
00011 #include "touch_tft.h"
00012 
00013 #define WIDTH 320
00014 #define HEIGHT 240
00015 
00016 touch_tft tt(p18,p19,p16,p17,p11, p12, p13, p14, p15,"TFT"); // x+,x-,y+,y-,mosi, miso, sclk, cs, reset
00017 
00018 void drawMandelbrot(float centrex, float centrey, float zoom, int maxIter) {
00019     float xmin = centrex - 1.0/zoom;
00020     float xmax = centrex + 1.0/zoom;
00021     float ymin = centrey - HEIGHT / (WIDTH * zoom);
00022     float ymax = centrey + HEIGHT / (WIDTH *zoom);
00023 
00024     float dx = (xmax - xmin) / WIDTH;
00025     float dy = (ymax - ymin) / HEIGHT;
00026 
00027     float y = ymin;
00028 
00029     float c;
00030     unsigned int cr, cg, cb;
00031     
00032     for (int j = 0; j < HEIGHT; j++) {
00033         float x = xmin;
00034 
00035         for (int i = 0;  i < WIDTH; i++) {
00036             float a = x;
00037             float b = y;
00038             int n = 0;
00039 
00040             while (n < maxIter) {
00041                 float aa = a * a;
00042                 float bb = b * b;
00043                 float twoab = 2.0 * a * b;
00044 
00045                 a = aa - bb + x;
00046                 b = twoab + y;
00047 
00048                 if(aa + bb > 16.0) {
00049                     break;
00050                 }
00051                 n++;
00052             }
00053 
00054             if (n == maxIter) {
00055                 //It's in the set - Black
00056                 tt.pixel(i,j,Black);
00057             } else {
00058                 //Not in the set - pick a colour
00059                 c = 3.0 * (maxIter-n)/maxIter;
00060                 cr = ((c < 1.0) ? 255 * ( 1.0 - c) : (c > 2.0) ? 255 * (c - 2.0) : 0);
00061                 cg = ((c < 1.0) ? 255 * c : (c > 2.0) ? 0 : 255 * (2.0 - c));
00062                 cb = ((c < 1.0) ? 0 : (c > 2.0) ? 255 * (3.0 - c) : 255 * (c - 1.0));
00063                 tt.pixel(i,j, RGB(cr,cg,cb));
00064             }
00065             x += dx;
00066         }
00067         y += dy;
00068     }
00069 }
00070 
00071 int main()
00072 {
00073     //Setup screen
00074     tt.claim(stdout);        // send stdout to the TFT display
00075     tt.background(Black);    // set background to black
00076     tt.foreground(White);    // set chars to white
00077     tt.cls();                // clear the screen
00078     tt.set_font((unsigned char*) Arial12x12);  // select the font
00079     tt.set_orientation(1);
00080     tt.calibrate();          // calibrate the touch
00081     point p;
00082 
00083     tt.locate(0,0);
00084 
00085     //Setup base Mandelbrot
00086     float centrex = -0.5;
00087     float centrey = 0.0;
00088     float zoom=0.5;
00089     int maxiterations = 150;
00090 
00091     while(true) {
00092         //Draw it    
00093         drawMandelbrot(centrex, centrey, zoom, maxiterations);
00094     
00095         //Wait for a touch
00096         p=tt.get_touch();
00097         while(!tt.is_touched(p)) {
00098             p=tt.get_touch();
00099         }
00100         //Set new centre and zoom
00101         p = tt.to_pixel(p);
00102         centrex += (2.0 * p.x - WIDTH) / (zoom * WIDTH);
00103         centrey += (2.0 * p.y - HEIGHT) / (zoom * WIDTH);
00104         zoom *= 4.0;
00105         tt.rect(p.x - WIDTH / 8.0, p.y - HEIGHT / 8.0, p.x + WIDTH / 8.0, p.y + HEIGHT / 8.0, Yellow);  
00106     }
00107 }