84 lines
2.4 KiB
C++
84 lines
2.4 KiB
C++
// Based on sketch here:
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// https://github.com/OpenHDZ/Arduino-experimentation
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// Adapted for TFT_eSPI library
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// Note: a high number of floating point calculations are needed
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// for each pixel so rendering will be quite slow.
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// For best performance use a Teensy 4.x (600MHz CPU clock).
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#include <TFT_eSPI.h> // Hardware-specific library
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TFT_eSPI tft = TFT_eSPI(); // Invoke custom library
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const uint16_t MAX_ITERATION = 300; // Nombre de couleurs
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#define SCREEN_WIDTH tft.width() //
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#define SCREEN_HEIGHT tft.height() // Taille de l'écran
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static float zoom = 0.5;
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/* Fonction setup */
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void setup() {
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/* Initialise l'écran LCD */
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tft.begin();
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tft.setRotation(1);
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tft.fillScreen(TFT_BLACK);
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tft.setFreeFont(&FreeMono9pt7b);
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}
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/* Fonction loop() */
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void loop() {
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/* Dessine la fractale */
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draw_Julia(-0.8,+0.156,zoom);
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tft.fillRect(0, 0, 150, 20, TFT_BLACK);
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tft.setCursor(0,15);
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tft.setTextColor(TFT_WHITE);
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tft.print(" Zoom = ");
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tft.println(zoom);
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delay(2000);
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zoom *= 1.5;
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if (zoom > 100) zoom = 0.5;
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}
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/*
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Dessine une fractale de Julia
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*/
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void draw_Julia(float c_r, float c_i, float zoom) {
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tft.setCursor(0,0);
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float new_r = 0.0, new_i = 0.0, old_r = 0.0, old_i = 0.0;
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/* Pour chaque pixel en X */
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for(int16_t x = SCREEN_WIDTH/2 - 1; x >= 0; x--) { // Rely on inverted symettry
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/* Pour chaque pixel en Y */
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for(uint16_t y = 0; y < SCREEN_HEIGHT; y++) {
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old_r = 1.5 * (x - SCREEN_WIDTH / 2) / (0.5 * zoom * SCREEN_WIDTH);
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old_i = (y - SCREEN_HEIGHT / 2) / (0.5 * zoom * SCREEN_HEIGHT);
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uint16_t i = 0;
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while ((old_r * old_r + old_i * old_i) < 4.0 && i < MAX_ITERATION) {
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new_r = old_r * old_r - old_i * old_i ;
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new_i = 2.0 * old_r * old_i;
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old_r = new_r+c_r;
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old_i = new_i+c_i;
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i++;
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}
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/* Affiche le pixel */
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if (i < 100){
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tft.drawPixel(x,y,tft.color565(255,255,map(i,0,100,255,0)));
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tft.drawPixel(SCREEN_WIDTH - x - 1,SCREEN_HEIGHT - y - 1,tft.color565(255,255,map(i,0,100,255,0)));
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}if(i<200){
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tft.drawPixel(x,y,tft.color565(255,map(i,100,200,255,0),0));
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tft.drawPixel(SCREEN_WIDTH - x - 1,SCREEN_HEIGHT - y - 1,tft.color565(255,map(i,100,200,255,0),0));
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}else{
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tft.drawPixel(x,y,tft.color565(map(i,200,300,255,0),0,0));
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tft.drawPixel(SCREEN_WIDTH - x - 1,SCREEN_HEIGHT - y - 1,tft.color565(map(i,200,300,255,0),0,0));
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}
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}
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}
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}
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