acid-drop

- Hacking the planet from a LilyGo T-Deck using custom firmware
git clone git://git.acid.vegas/acid-drop.git
TFT_FillArcSpiral.ino (4286B)
      1 // This sketch tests a fillArc function that has been adapted to permit the drawing of spirals
      2 
      3 // Sketch also includes (but does not use) a function to change the brightness of a colour
      4 
      5 #include <TFT_eSPI.h> // Hardware-specific library
      6 #include <SPI.h>
      7 
      8 TFT_eSPI tft = TFT_eSPI();       // Invoke custom library
      9 
     10 #define DEG2RAD 0.0174532925
     11 
     12 int segment = 0;
     13 unsigned int col = 0;
     14 int delta = -1;
     15 
     16   byte red = 31; // Red is the top 5 bits of a 16 bit colour value
     17   byte green = 0;// Green is the middle 6 bits
     18   byte blue = 0; // Blue is the bottom 5 bits
     19   byte state = 0;
     20 
     21 void setup(void) {
     22   tft.begin();
     23 
     24   tft.setRotation(1);
     25 
     26   tft.fillScreen(TFT_BLACK);
     27 }
     28 
     29 
     30 void loop() {
     31   fillArc(160, 120, segment*6, 1, 120-segment/4, 120-segment/4, 3, rainbow(col));
     32 
     33   segment+=delta;
     34   col+=1;
     35   if (col>191) col = 0;
     36   if (segment <0) delta = 1;
     37   if (segment >298) delta = -1; // ~5 turns in the spiral (300*6 degrees)
     38   //delay(5); // Slow drawing down
     39 }
     40 
     41 // #########################################################################
     42 // Draw an arc with a defined thickness (modified to aid drawing spirals)
     43 // #########################################################################
     44 
     45 // x,y == coords of centre of arc
     46 // start_angle = 0 - 359
     47 // seg_count = number of 3 degree segments to draw (120 => 360 degree arc)
     48 // rx = x axis radius
     49 // yx = y axis radius
     50 // w  = width (thickness) of arc in pixels
     51 // colour = 16 bit colour value
     52 // Note if rx and ry are the same an arc of a circle is drawn
     53 
     54 void fillArc(int x, int y, int start_angle, int seg_count, int rx, int ry, int w, unsigned int colour)
     55 {
     56 
     57   // Make the segment size 7 degrees to prevent gaps when drawing spirals
     58   byte seg = 7; // Angle a single segment subtends (made more than 6 deg. for spiral drawing)
     59   byte inc = 6; // Draw segments every 6 degrees
     60 
     61   // Draw colour blocks every inc degrees
     62   for (int i = start_angle; i < start_angle + seg * seg_count; i += inc) {
     63     // Calculate pair of coordinates for segment start
     64     float sx = cos((i - 90) * DEG2RAD);
     65     float sy = sin((i - 90) * DEG2RAD);
     66     uint16_t x0 = sx * (rx - w) + x;
     67     uint16_t y0 = sy * (ry - w) + y;
     68     uint16_t x1 = sx * rx + x;
     69     uint16_t y1 = sy * ry + y;
     70 
     71     // Calculate pair of coordinates for segment end
     72     float sx2 = cos((i + seg - 90) * DEG2RAD);
     73     float sy2 = sin((i + seg - 90) * DEG2RAD);
     74     int x2 = sx2 * (rx - w) + x;
     75     int y2 = sy2 * (ry - w) + y;
     76     int x3 = sx2 * rx + x;
     77     int y3 = sy2 * ry + y;
     78 
     79     tft.fillTriangle(x0, y0, x1, y1, x2, y2, colour);
     80     tft.fillTriangle(x1, y1, x2, y2, x3, y3, colour);
     81   }
     82 }
     83 
     84 // #########################################################################
     85 // Return a 16 bit colour with brightness 0 - 100%
     86 // #########################################################################
     87 unsigned int brightness(unsigned int colour, int brightness)
     88 {
     89   byte red  = colour >> 11;
     90   byte green = (colour & 0x7E0) >> 5;
     91   byte blue   = colour & 0x1F;
     92 
     93   blue = (blue * brightness)/100;
     94   green = (green * brightness)/100;
     95   red = (red * brightness)/100;
     96 
     97   return (red << 11) + (green << 5) + blue;
     98 }
     99 
    100 // #########################################################################
    101 // Return a 16 bit rainbow colour
    102 // #########################################################################
    103 unsigned int rainbow(byte value)
    104 {
    105   // Value is expected to be in range 0-127
    106   // The value is converted to a spectrum colour from 0 = blue through to 127 = red
    107 
    108     switch (state) {
    109       case 0:
    110         green ++;
    111         if (green == 64) {
    112           green = 63;
    113           state = 1;
    114         }
    115         break;
    116       case 1:
    117         red--;
    118         if (red == 255) {
    119           red = 0;
    120           state = 2;
    121         }
    122         break;
    123       case 2:
    124         blue ++;
    125         if (blue == 32) {
    126           blue = 31;
    127           state = 3;
    128         }
    129         break;
    130       case 3:
    131         green --;
    132         if (green == 255) {
    133           green = 0;
    134           state = 4;
    135         }
    136         break;
    137       case 4:
    138         red ++;
    139         if (red == 32) {
    140           red = 31;
    141           state = 5;
    142         }
    143         break;
    144       case 5:
    145         blue --;
    146         if (blue == 255) {
    147           blue = 0;
    148           state = 0;
    149         }
    150         break;
    151     }
    152     return red << 11 | green << 5 | blue;
    153 }
    154