tfttest.c

#include <SPI.h>
#include <TFT_eSPI.h>
#define PIXELPIN   5
#define NUMPIXELS  5
#define pixlux    20  
#define BUTTON_1        35
#define BUTTON_2        0
#define SW 135
#define SH 240

TFT_eSPI tft = TFT_eSPI(SW, SH);

float col[3];

void setup() {
  tft.begin();
  tft.setRotation(0);
  tft.fillScreen(TFT_BLACK);
  tft.setTextColor(0x5E85);
  tft.setTextSize(3);
  pinMode(BUTTON_1, INPUT_PULLUP);
  pinMode(BUTTON_2, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(BUTTON_1),reset, FALLING);
  attachInterrupt(digitalPinToInterrupt(BUTTON_2),reset, FALLING);
}

float fract(float x) { return x - int(x); }

float mix(float a, float b, float t) { return a + (b - a) * t; }

float step(float e, float x) { return x < e ? 0.0 : 1.0; } 

float* hsv2rgb(float h, float s, float b, float* rgb) {
  rgb[0] = b * mix(1.0, constrain(abs(fract(h + 1.0) * 6.0 - 3.0) - 1.0, 0.0, 1.0), s);
  rgb[1] = b * mix(1.0, constrain(abs(fract(h + 0.6666666) * 6.0 - 3.0) - 1.0, 0.0, 1.0), s);
  rgb[2] = b * mix(1.0, constrain(abs(fract(h + 0.3333333) * 6.0 - 3.0) - 1.0, 0.0, 1.0), s);
  return rgb;
}

void reset(){
  }

float ramp_step = SH/360.0;

void loop() {
  for (int i=0; i++; i<SH){
    tft.drawLine(0, i, SW, i, hsv2rgb(ramp_step*i, 1.0, 1.0, col));
  }
}