Mandelbrot.cpp

// Original demo by Stefan Sauer (@ensonic)
// make_pal is from @Spinal's Mode13 demo, with modifications

#include "Pokitto.h"

Pokitto::Core game;

#define RGB888_565(r, g, b) ((r >> 3) | ((g >> 2) << 5) | ((b >> 3) << 11))
#define GRAY888_565(g) ((g >> 3) | ((g >> 2) << 5) | ((g >> 3) << 11))

/* calculate mandelbrot/julia set
 * KEYS
 * - color cycle: left, right
 * - zoom-in/out: up, down
 * - move center: A + up/down/left/right
 *
 * TODO:
 * - increase/decrease max iter: B + up/down 
 * - switch between mandel/julia: C
 *   - will also reset x1/x2/Y1/y2 and max-iter
 */

static const uint8_t width = (POK_LCD_W);
static const uint8_t height = (POK_LCD_H);
 
static float x1 = -2.2;
static float x2 = 1.5;
static float xd = x2 - x1;
static float xs = xd / width;
static float Y1 = -1.5;
static float y2 = 1.5;
static float yd = y2 - Y1;
static float ys = yd / height;

void make_pal(void){
  int a,s,r,g,b;
  for(a=0; a<=63; a++){
    s = 0; 	r = a; 		g = 63-a;	b = 0;
    Pokitto::Display::palette[a+s] = game.display.RGBto565(r*13,g*13,b*13);
    s = 64; r = 63-a;	g = 0;		b = a;
    Pokitto::Display::palette[a+s] = game.display.RGBto565(r*13,g*13,b*13);
    s = 128; r = 0;	 	g = 0;		b = 63-a;
    Pokitto::Display::palette[a+s] = game.display.RGBto565(r*13,g*13,b*13);
    s = 192; r = 0;		g = a;		b = 0;
    Pokitto::Display::palette[a+s] = game.display.RGBto565(r*13,g*13,b*13);
  }
  // game.display.load565Palette(&pal[0]); // load a palette the same way as any other palette in any other screen mode
}


void rotatePalette(int8_t step) {
  if( step == 0 ) return;
  int dir, start, end;
  
  if( step > 0 ){
    dir = 1;
    start = 0;
    end = PALETTE_SIZE;
  }else{
    dir = -1;
    start = PALETTE_SIZE-1;
    end = -1;
  }

  for( int i=start; i!=end; i+=dir ){
    int src = i+step;
    if( src < 0 ) src += PALETTE_SIZE;
    else if( src >= PALETTE_SIZE ) src -= PALETTE_SIZE;
    Pokitto::Display::palette[i] = Pokitto::Display::palette[src];
  }

}

static uint16_t mandel_pixel(float startReal, float startImag) {
    float zReal = startReal;
    float zImag = startImag;

    for (uint16_t counter = 0; counter < 50; counter++) {
        // z := z*z + c
        float r2 = zReal * zReal;
        float i2 = zImag * zImag;
        if (r2 + i2 > 4.0) {
            return counter;
        }
        zImag = 2.0 * zReal * zImag + startImag;
        zReal = r2 - i2 + startReal;
    }
    return 0;
}

void drawPixel( int32_t x, int32_t y, int32_t col ){
  col &= 3;
  int32_t i = y*(width>>2) + (x>>2);
  uint8_t pixel = Pokitto::Display::screenbuffer[i];
  uint8_t column = x&0x03;
  
  if (column==3) pixel = (pixel&0xFC)|(col); // bits 0-1
  else if (column==2) pixel = (pixel&0xF3)|(col<<2); // bits 2-3
  else if (column==1) pixel = (pixel&0xCF)|(col<<4); // bits 4-5
  else pixel = (pixel&0x3F)|(col<<6); // bits 6-7
  
  Pokitto::Display::screenbuffer[i] = pixel;
  
}

static void mandel_screen(void) {
    for (uint8_t ypos = 0; ypos < height; ypos++) {
        float startImag = Y1 + (ys * ypos);    
        for (uint8_t xpos = 0; xpos < width; xpos++) {
            float startReal = x1 + (xs * xpos);
            uint8_t color = mandel_pixel(startReal, startImag) & 0x03;
            // game.display.drawPixel(xpos, ypos, color);
	    drawPixel(xpos, ypos, color);
        }
	rotatePalette(1);
        game.display.update();
    }
}

int main () {
    game.begin();
    // game.display.load565Palette(palette);
    make_pal();

    // don't clear the screen
    game.display.persistence = 1;
    bool recalc = true;
    
    while (game.isRunning()) {
        if (game.update()) {
	    rotatePalette(1);
            if (game.aBtn()) {
                // scroll
                if (game.leftBtn()) {
                    float mx = 10.0 * xs;
                    x1 -= mx;
                    x2 -= mx;
                    recalc = true;
                } else if (game.rightBtn()) {
                    float mx = 10.0 * xs;
                    x1 += mx;
                    x2 += mx;
                    recalc = true;
                } else if (game.upBtn()) {
                    float my = 10.0 * ys;
                    Y1 -= my;
                    y2 -= my;
                    recalc = true;
                } else if (game.downBtn()) {
                    float my = 10.0 * ys;
                    Y1 += my;
                    y2 += my;
                    recalc = true;
                }
            } else {
                // cycle colors & zoom
                if (game.upBtn()) {
                    // zoom in
                    xd /= 2.0;
                    float xm = x1 + xd;
                    x1 = xm - xd / 2.0;
                    x2 = xm + xd / 2.0;
                    xs = xd / width;
                    
                    yd /= 2.0;
                    float ym = Y1 + yd;
                    Y1 = ym - yd / 2.0;
                    y2 = ym + yd / 2.0;
                    ys = yd / height;

                    recalc = true;
                } else if (game.downBtn()) {
                    // zoom out
                    float xm = x1 + xd / 2.0;
                    x1 = xm - xd;
                    x2 = xm + xd;
                    xd *= 2.0;
                    xs = xd / width;
                    
                    float ym = Y1 + yd / 2.0;
                    Y1 = ym - yd;
                    y2 = ym + yd;
                    yd *= 2.0;
                    ys = yd / height;
                    
                    recalc = true;
                }
            }
            if (recalc) {
                mandel_screen();
                recalc = false;
            }
        }
    }
}