155 lines
4.2 KiB
C++
155 lines
4.2 KiB
C++
// This sketch tests a fillArc function that has been adapted to permit the drawing of spirals
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// Sketch also includes (but does not use) a function to change the brightness of a colour
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#include <TFT_eSPI.h> // Hardware-specific library
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#include <SPI.h>
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TFT_eSPI tft = TFT_eSPI(); // Invoke custom library
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#define DEG2RAD 0.0174532925
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int segment = 0;
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unsigned int col = 0;
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int delta = -1;
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byte red = 31; // Red is the top 5 bits of a 16 bit colour value
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byte green = 0;// Green is the middle 6 bits
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byte blue = 0; // Blue is the bottom 5 bits
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byte state = 0;
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void setup(void) {
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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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}
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void loop() {
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fillArc(160, 120, segment*6, 1, 120-segment/4, 120-segment/4, 3, rainbow(col));
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segment+=delta;
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col+=1;
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if (col>191) col = 0;
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if (segment <0) delta = 1;
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if (segment >298) delta = -1; // ~5 turns in the spiral (300*6 degrees)
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//delay(5); // Slow drawing down
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}
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// #########################################################################
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// Draw an arc with a defined thickness (modified to aid drawing spirals)
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// #########################################################################
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// x,y == coords of centre of arc
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// start_angle = 0 - 359
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// seg_count = number of 3 degree segments to draw (120 => 360 degree arc)
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// rx = x axis radius
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// yx = y axis radius
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// w = width (thickness) of arc in pixels
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// colour = 16 bit colour value
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// Note if rx and ry are the same an arc of a circle is drawn
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int fillArc(int x, int y, int start_angle, int seg_count, int rx, int ry, int w, unsigned int colour)
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{
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// Make the segment size 7 degrees to prevent gaps when drawing spirals
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byte seg = 7; // Angle a single segment subtends (made more than 6 deg. for spiral drawing)
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byte inc = 6; // Draw segments every 6 degrees
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// Draw colour blocks every inc degrees
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for (int i = start_angle; i < start_angle + seg * seg_count; i += inc) {
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// Calculate pair of coordinates for segment start
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float sx = cos((i - 90) * DEG2RAD);
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float sy = sin((i - 90) * DEG2RAD);
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uint16_t x0 = sx * (rx - w) + x;
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uint16_t y0 = sy * (ry - w) + y;
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uint16_t x1 = sx * rx + x;
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uint16_t y1 = sy * ry + y;
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// Calculate pair of coordinates for segment end
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float sx2 = cos((i + seg - 90) * DEG2RAD);
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float sy2 = sin((i + seg - 90) * DEG2RAD);
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int x2 = sx2 * (rx - w) + x;
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int y2 = sy2 * (ry - w) + y;
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int x3 = sx2 * rx + x;
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int y3 = sy2 * ry + y;
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tft.fillTriangle(x0, y0, x1, y1, x2, y2, colour);
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tft.fillTriangle(x1, y1, x2, y2, x3, y3, colour);
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}
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}
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// #########################################################################
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// Return a 16 bit colour with brightness 0 - 100%
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// #########################################################################
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unsigned int brightness(unsigned int colour, int brightness)
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{
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byte red = colour >> 11;
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byte green = (colour & 0x7E0) >> 5;
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byte blue = colour & 0x1F;
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blue = (blue * brightness)/100;
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green = (green * brightness)/100;
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red = (red * brightness)/100;
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return (red << 11) + (green << 5) + blue;
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}
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// #########################################################################
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// Return a 16 bit rainbow colour
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// #########################################################################
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unsigned int rainbow(byte value)
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{
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// Value is expected to be in range 0-127
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// The value is converted to a spectrum colour from 0 = blue through to 127 = red
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switch (state) {
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case 0:
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green ++;
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if (green == 64) {
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green = 63;
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state = 1;
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}
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break;
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case 1:
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red--;
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if (red == 255) {
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red = 0;
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state = 2;
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}
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break;
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case 2:
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blue ++;
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if (blue == 32) {
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blue = 31;
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state = 3;
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}
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break;
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case 3:
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green --;
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if (green == 255) {
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green = 0;
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state = 4;
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}
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break;
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case 4:
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red ++;
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if (red == 32) {
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red = 31;
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state = 5;
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}
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break;
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case 5:
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blue --;
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if (blue == 255) {
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blue = 0;
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state = 0;
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}
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break;
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}
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return red << 11 | green << 5 | blue;
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}
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