UwUGL/helpers.cpp

#pragma once

#include <stdint.h>
#include "datatypes.cpp"

namespace UwU {
  
  class Helpers {
    public:
      static uint8_t lerp8(uint8_t a, uint8_t b, uint8_t t) {
        uint16_t product = (a * (255 - t)) + (b * t);
        return product / 255;
      }

      static Color lerpColor(Color a, Color b, uint8_t t) {
        Color mixed = Color();
        mixed.r = lerp8(a.r, b.r, t);
        mixed.g = lerp8(a.g, b.g, t);
        mixed.b = lerp8(a.b, b.b, t);
        mixed.a = lerp8(a.a, b.a, t); // maybe the alpha channel should be handled differently?
        return mixed;
      }

      static void bresenhamLow(uint16_t x0, int16_t y0, uint16_t x1, int16_t y1, int16_t* LUT) {
        int16_t dx = int16_t(x1) - int16_t(x0);
        int16_t dy = y1 - y0;
        int16_t yi = 1;
        if (dy < 0) {
          yi = -1;
          dy = -dy;
        }
        int16_t d = (2 * dy) - dx;
        int16_t y = y0;
        for (uint16_t x = x0; x <= x1; x++) {
          LUT[x] = y;
          if (d > 0) {
            y += yi;
            d += (2 * (dy - dx));
          } else {
            d += (2 * dy);
          }
        }
        return;
      }

      static void bresenhamHigh(uint16_t x0, int16_t y0, uint16_t x1, int16_t y1, int16_t* LUT) {
        int16_t dx = (int16_t)x1 - (int16_t)x0;
        int16_t dy = y1 - y0;
        int16_t xi = 1;
        if (dx < 0) {
          xi = -1;
          dx = -dx;
        }
        int16_t d = (2 * dx) - dy;
        int16_t x = (int16_t)x0;
        for (int16_t y = y0; y <= y1; y++) {
          LUT[x] = y;
          if (d > 0) {
            x += xi;
            d += (2 * (dx - dy));
          } else {
            d += (2 * dx);
          }
        }
        return;
      }

      // x1 must >= x0 && LUT must be size x1 + 1
      static void bresenham(uint16_t x0, int16_t y0, uint16_t x1, int16_t y1, int16_t* LUT) {
        if (x0 == x1) {
          // catch vline condition
          LUT[x0] = y1;
          return;
        }
        if (y0 == y1) {
          // catch hline condition
          for (uint16_t i = x0; i <= x1; i++) {
            LUT[i] = y1;
          }
          return;
        }
        if (abs(y1 - y0) <= x1) {
          bresenhamLow(x0, y0, x1, y1, LUT);
        } else {
          if (y0 > y1) {
            bresenhamHigh(x1, y1, x0, y0, LUT);
          } else {
            bresenhamHigh(x0, y0, x1, y1, LUT);
          }
        }
        return;
      }
  };
}