package main

import (
	"github.com/hajimehoshi/ebiten"
	"github.com/peterhellberg/gfx"
)

var (
	w, h    = 256, 256
	palette = gfx.PaletteEN4
	center  = gfx.V(128, 128)
	pos     = center
	p       = gfx.Polygon{
		{-64, -64},
		{-32, -32},
		{-64, 64},
		{64, 64},
		{64, -64},
	}
)

func main() {
	ebiten.SetFullscreen(true)
	ebiten.Run(run, w, h, 1, "Ebiten GFX Moving Polygon")
}

func run(screen *ebiten.Image) error {
	if ebiten.IsKeyPressed(ebiten.KeyEscape) || ebiten.IsKeyPressed(ebiten.KeyQ) {
		return gfx.ErrDone
	}

	if ebiten.IsDrawingSkipped() {
		return nil
	}

	m := gfx.NewPaletted(w, h, palette, palette[3])
	d := float64(int(pos.X) % 360)

	matrix := gfx.IM.Moved(pos)

	tp := center

	touches := ebiten.Touches()

	switch {
	case len(touches) > 0:
		tp = gfx.IV(touches[0].Position())
	case ebiten.IsMouseButtonPressed(ebiten.MouseButtonLeft):
		tp = gfx.IV(ebiten.CursorPosition())
	}

	pos = gfx.Lerp(pos, tp, 0.2)

	gfx.DrawPolygon(m, p.Project(matrix), 0, palette[2])
	gfx.DrawPolygon(m, p.Project(matrix.Scaled(pos, 0.5).RotatedDegrees(pos, d)), 0, palette[1])

	gfx.DrawFastFilledCircle(m, pos, 4, palette[0])

	return screen.ReplacePixels(m.Pixels())
}