old-9heroja/terrain/terrain.go

package terrain

import (
	"bytes"
	"github.com/hajimehoshi/ebiten/v2"
	"gitlab.com/kbr4/9heroja/resources"
	"image"
	"log"
)

var (
	grassImage *ebiten.Image
)

type Terrain struct {
	positionX float64
	positionY float64
}

func (t *Terrain) DrawTerrain(screen *ebiten.Image) {
	screenWidth := screen.Bounds().Max.X
	screenHeight := screen.Bounds().Max.Y
	offsetX := int(t.positionX) % 64
	offsetY := int(t.positionY) % 64
	op := &ebiten.DrawImageOptions{}
	for i := -1; i <= screenWidth/64+1; i++ {
		for j := -1; j <= screenHeight/64+1; j++ {
			// ground
			op.GeoM.Reset()
			op.GeoM.Translate(float64(i*64+offsetX), float64(j*64+offsetY))
			screen.DrawImage(grassImage.SubImage(image.Rect(32, 160, 32+64, 160+64)).(*ebiten.Image), op)
		}

	}
}

func init() {
	img, _, err := image.Decode(bytes.NewReader(resources.Grass_png))
	if err != nil {
		log.Fatal(err)
	}
	grassImage = ebiten.NewImageFromImage(img)
}

func NewTerrain() *Terrain {
	return &Terrain{
		positionX: 0,
		positionY: 0,
	}
}

func (t *Terrain) GoDown() {
	t.positionY += 1
}