openquell/components/position.go

package components

import (
	"fmt"
	"image"
	. "openquell/config"
)

// physical location on screen
type Position struct {
	X        int
	Y        int
	Cellsize int
	Rect     *image.Rectangle
}

func (position *Position) Update(x, y int, size ...int) {
	if len(size) == 1 {
		position.Cellsize = size[0]
	}

	position.X = x
	position.Y = y

	rect := image.Rect(x, y, x+position.Cellsize, y+position.Cellsize)
	position.Rect = &rect
}

func NewPosition(point image.Point, cellsize int) *Position {
	position := &Position{}
	position.Update(point.X*cellsize, point.Y*cellsize, cellsize)
	return position
}

func (position *Position) GetMoved(velosity *Velocity) *Position {
	pos := &Position{}
	pos.Update(position.X+velosity.Data.X, position.Y+velosity.Data.Y, position.Cellsize)

	return pos
}

func (position *Position) Point() image.Point {
	return image.Point{position.X / position.Cellsize, position.Y / position.Cellsize}
}

func (position *Position) Left() int {
	return position.X
}

func (position *Position) Right() int {
	return position.X + position.Cellsize
}

func (position *Position) Top() int {
	return position.Y
}

func (position *Position) Bottom() int {
	return position.Y + position.Cellsize
}

func (position *Position) String() string {
	return fmt.Sprintf("[%d,%d](Left:%d,Top:%d) x (Right:%d,Bottom:%d)",
		position.X/32,
		position.Y/32,
		position.X,
		position.Y,
		position.Right(),
		position.Bottom(),
	)
}

func (position *Position) Move(velocity *Velocity) {
	position.Update(position.X+velocity.Data.X, position.Y+velocity.Data.Y)
}

func (position *Position) Set(newpos *Position) {
	position.Update(newpos.X, newpos.Y)
}

func (tile *Position) Intersects(moving *Position, velocity *Velocity) (bool, *Position) {
	object := moving.GetMoved(velocity)

	is := tile.Rect.Bounds().Intersect(object.Rect.Bounds())
	if is != image.ZR {
		fmt.Printf("    velocity: %d,%d\n", velocity.Data.X, velocity.Data.Y)
		fmt.Printf("      player: %s\n", moving.Rect)
		fmt.Printf("moved player: %s\n", object.Rect)
		fmt.Printf("collision at: %s\n", is)
		// collision, snap into neighbouring tile depending on the direction
		switch velocity.Direction {
		case West:
			object.Update(tile.Rect.Max.X, tile.Y)
		case East:
			object.Update(tile.Rect.Min.X-tile.Cellsize, tile.Y)
		case South:
			object.Update(tile.X, tile.Rect.Min.Y-tile.Cellsize)
		case North:
			object.Update(tile.X, tile.Rect.Max.Y)
		}

		return true, object
	}

	return false, nil
}