package main

import (
	"math"
)

func Bresenham2(fb *Framebuffer, color uint, x0 int, y0 int, x1 int, y1 int) {
	dx := int(math.Abs(float64(x1 - x0)))
	sx := -1
	if x0 < x1 {
		sx = 1
	}
	dy := -int(math.Abs(float64(y1 - y0)))
	sy := -1
	if y0 < y1 {
		sy = 1
	}
	err := dx + dy

	for {
		fb.SetSafe(uint(x0), uint(y0), color)
		if x0 == x1 && y0 == y1 {
			break
		}
		e2 := 2 * err
		if e2 >= dy {
			if x0 == x1 {
				break
			}
			err += dy
			x0 += sx
		}
		if e2 <= dx {
			if y0 == y1 {
				break
			}
			err += dx
			y0 += sy
		}
	}
}

func line(fb *Framebuffer, color uint, v0 Vec2i, v1 Vec2i) {
	Bresenham2(fb, color, v0.X, v0.Y, v1.X, v1.Y)
}

func Triangle1(fb *Framebuffer, color uint, v0 Vec2i, v1 Vec2i, v2 Vec2i) {
	line(fb, color, v0, v1)
	line(fb, color, v1, v2)
	line(fb, color, v2, v0)
}