UwUGL/primatives/trapezoid.cpp

#pragma once

#include <stdint.h>
#include <algorithm>

#include "../datatypes.cpp"
#include "../helpers.cpp"
#include "../buffer.cpp"
#include "../mappers/mappers.h"
#include "../textures/textures.h"

namespace UwU {
  // trapezoid (horizontally constrained)
  class Trapezoid {
    public:
      Trapezoid(uint16_t y0, uint16_t y1, uint16_t xl0, uint16_t xl1, uint16_t xr0, uint16_t xr1) {
        this->y0 = y0;
        this->y1 = y1;
        this->xl0 = xl0;
        this->xl1 = xl1;
        this->xr0 = xr0;
        this->xr1 = xr1;
      }
      Trapezoid() {}
      uint16_t y0;
      uint16_t y1;
      uint16_t xl0;
      uint16_t xl1;
      uint16_t xr0;
      uint16_t xr1;
      
      // Draw a horizontally bounded trapezoid
      // y1 >= y0
      template <class MapperT, class TextureT>
      void draw (Buffer buffer, MapperBase<MapperT>& mapper, TextureBase<TextureT>& texture) {
        uint16_t height = 1 + y1 - y0;
        int16_t LeftBound[height];
        int16_t RightBound[height];
        
        Helpers::bresenham(0, xl0, y1 - y0, xl1, LeftBound);
        Helpers::bresenham(0, xr0, y1 - y0, xr1, RightBound);

        uint16_t x0 = std::min(xl0, xl1);
        
        for (uint16_t i = 0; i < height; i++) {
          for (uint16_t x = LeftBound[i]; x <= RightBound[i]; x++) {
            Coord2 uv = mapper.map(x0, y0, x, i + y0);
            buffer.drawPixel(x, i + y0, texture.texel(uv.x, uv.y));
          }
        }
        return;
      }
  };
}