fluids/game/game.go

package game

import (
	"fluids/elements"
	"fluids/gamedata"
	"fmt"
	"image/color"
	"math"

	"github.com/hajimehoshi/ebiten/v2"
	"github.com/hajimehoshi/ebiten/v2/ebitenutil"
	"github.com/hajimehoshi/ebiten/v2/inpututil"
)

const (
	GameWidth  = 640
	GameHeight = 360
	GameFSDW   = 200
	GameFSDH   = 100
	GameSims   = 3 //number of total sims
)

type Game struct {
	//control data
	cycle       int
	paused      bool
	fluidsimidx int

	//key elements
	fluidsimd  *elements.FluidSimD
	fluidsim10 []*elements.FluidSim10
	alertbox   *elements.Alert
	flask      *elements.RoundedBottomFlask

	//cache elements
	fluidsim10width  float64
	fluidsim10height float64

	//other
	fluidsim10angle float64 //purely for debugging
	mdown           bool
	mdx, mdy        int
	mdangle         float64 //angle at mousedown
	mfangle         float64 //last flask angle

	//colors
	flaskcolor color.RGBA
}

func NewGame() *Game {
	g := &Game{
		paused:      false,
		fluidsimidx: 0,
		alertbox:    elements.NewAlert(),
		fluidsimd:   elements.NewFluidSimD(),
		flask:       elements.NewRoundedBottomFlask(),
	}

	g.Initialize()
	return g
}

func (g *Game) Update() error {

	g.ParseInputs()

	if !g.paused {
		switch g.fluidsimidx {
		case 0:
			g.UpdateFlask()
		case 1:
			g.fluidsimd.Update()
		case 2:
			g.UpdateFluidsim10()
		default:
			break
		}
	}

	g.cycle++

	return nil
}

func (g *Game) UpdateFluidsim10() {
	for _, sim := range g.fluidsim10 {
		sim.Update()
	}
}

func (g *Game) Draw(screen *ebiten.Image) {
	screen.Clear()

	switch g.fluidsimidx {
	case 0:
		g.RenderFlask(screen)
	case 1:
		g.RenderFluidSimD(screen)
	case 2:
		g.RenderFluidSim10(screen)

	default:
		break
	}

	if g.paused {
		op := &ebiten.DrawImageOptions{}
		op.GeoM.Translate(50, 50)
		screen.DrawImage(g.alertbox.Sprite, op)
	}
}

func (g *Game) RenderFluidSimD(img *ebiten.Image) {
	g.fluidsimd.Draw()
	pos := g.fluidsimd.GetPosition()
	op := &ebiten.DrawImageOptions{}
	op.GeoM.Translate(pos.X, pos.Y)
	img.DrawImage(g.fluidsimd.GetSprite(), op)
}

func (g *Game) RenderFluidSim10(img *ebiten.Image) {

	for _, sim := range g.fluidsim10 {
		sim.Draw()

		angle := sim.GetAngle()
		pos := sim.GetPosition()
		op := &ebiten.DrawImageOptions{}
		op.GeoM.Translate(-g.fluidsim10width/2, -g.fluidsim10height/2)
		op.GeoM.Scale(1, -1)
		op.GeoM.Rotate(angle)
		//	op.GeoM.Translate(g.fluidsim10width/2, g.fluidsim10height/2)
		op.GeoM.Translate(pos.X, pos.Y)
		img.DrawImage(sim.GetSprite(), op)
	}

	//debug info
	x, y := ebiten.CursorPosition()
	deg := g.fluidsim10angle * 180 / math.Pi

	str := fmt.Sprintf("Mouse (x: %d, y: %d) Origin (x: %d, y: %d) Angle (%f)", x, y, GameWidth/2, GameHeight/2, deg)
	ebitenutil.DebugPrint(img, str)
}

func (g *Game) Layout(x, y int) (int, int) {
	return GameWidth, GameHeight
}

func (g *Game) ParseInputs() {

	//simulation specific updates
	switch g.fluidsimidx {
	case 0:
		g.ManageFlaskInputs()
	case 1:
		g.ManageFluidSimDInputs()
	case 2:
		g.ManageFluidSim10Inputs()

	default:
		break
	}

	//common updates
	if inpututil.IsKeyJustPressed(ebiten.KeyP) {
		g.paused = !g.paused
		g.alertbox.SetText("PAUSED")
		g.alertbox.Draw()
	}

	//swap fluid simulations
	if inpututil.IsKeyJustPressed(ebiten.KeyPageUp) {
		g.fluidsimidx = (g.fluidsimidx + 1) % GameSims
	}

	if inpututil.IsKeyJustPressed(ebiten.KeyPageDown) {
		g.fluidsimidx = g.fluidsimidx - 1
		if g.fluidsimidx < 0 {
			g.fluidsimidx = GameSims - 1
		}
	}

}

func (g *Game) ManageFluidSimDInputs() {
	//refresh particles
	if inpututil.IsKeyJustPressed(ebiten.KeyR) {
		g.fluidsimd.InitializeParticles()
	}

	//pause simulation
	if inpututil.IsKeyJustPressed(ebiten.KeyP) {
		g.fluidsimd.SetPaused(!g.fluidsimd.Paused())
	}

	//show quadtree quadrants
	if inpututil.IsKeyJustPressed(ebiten.KeyQ) {
		g.fluidsimd.SetRenderQuads(!g.fluidsimd.RenderQuads())
	}

	//enable collision resolution
	if inpututil.IsKeyJustPressed(ebiten.KeyC) {
		g.fluidsimd.SetResolveCollisions(!g.fluidsimd.ResolveCollisions())
	}

	//switch between collision resolvers
	if inpututil.IsKeyJustPressed(ebiten.KeyLeft) {
		g.fluidsimd.PreviousSolver()
	}

	if inpututil.IsKeyJustPressed(ebiten.KeyRight) {
		g.fluidsimd.NextSolver()
	}
}

func (g *Game) ManageFluidSim10Inputs() {
	//refresh particles
	if inpututil.IsKeyJustPressed(ebiten.KeyR) {
		for _, sim := range g.fluidsim10 {
			sim.Initialize()
			g.fluidsim10angle = 0
		}
	}

	if inpututil.IsMouseButtonJustPressed(ebiten.MouseButtonLeft) {
		g.mdown = true
		g.mdx, g.mdy = ebiten.CursorPosition()
	}

	if ebiten.IsMouseButtonPressed(ebiten.MouseButtonLeft) {
		if g.mdown {
			mx, my := ebiten.CursorPosition()

			for _, sim := range g.fluidsim10 {
				dx := float64(mx) - sim.GetPosition().X
				dy := float64(my) - sim.GetPosition().Y
				angle := math.Atan2(dy, dx)
				g.fluidsim10angle = angle
				sim.SetAngle(angle)
			}
		}
	}

	if inpututil.IsMouseButtonJustReleased(ebiten.MouseButtonLeft) {
		g.mdown = false
	}

	if inpututil.IsKeyJustPressed(ebiten.KeyB) {
		for _, sim := range g.fluidsim10 {
			sim.ToggleShape()
		}
	}

	if inpututil.IsKeyJustPressed(ebiten.KeyV) {
		for _, sim := range g.fluidsim10 {
			sim.ToggleParticles()
		}
	}

}

func (g *Game) Initialize() {

	//10MP Fluid Simulation Initialization
	g.fluidsim10 = append(g.fluidsim10, elements.NewFluidSim10())
	g.fluidsim10 = append(g.fluidsim10, elements.NewFluidSim10())

	g.fluidsim10width = float64(g.fluidsim10[0].GetSprite().Bounds().Dx())
	g.fluidsim10height = float64(g.fluidsim10[0].GetSprite().Bounds().Dy())

	x0 := float64(GameWidth / (len(g.fluidsim10) + 1))

	for i, sim := range g.fluidsim10 {

		pos := gamedata.Vector{
			X: x0 * float64(i+1),
			Y: GameHeight / 2.,
		}
		sim.SetPosition(pos)
	}

	//Flask Initialization
	pos := gamedata.Vector{
		X: GameWidth / 2,
		Y: GameHeight / 2,
	}
	g.flask.SetPosition(pos)
	g.flaskcolor = color.RGBA{R: 0xff, G: 0x00, B: 0x00, A: 0xff}
	g.flask.SetFluidColor(g.flaskcolor)

}

func (g *Game) ManageFlaskInputs() {
	if inpututil.IsKeyJustPressed(ebiten.KeyR) {
		g.flask.Initialize()
		g.mfangle = 0
		g.flask.SetAngle(g.mfangle)
		g.flask.SetFluidColor(g.flaskcolor)
	}

	if inpututil.IsMouseButtonJustPressed(ebiten.MouseButtonLeft) {
		//angle at mouse down is the zero angle
		g.mdown = true
		g.mdx, g.mdy = ebiten.CursorPosition()

		dx := float64(g.mdx) - g.flask.GetPosition().X
		dy := float64(g.mdy) - g.flask.GetPosition().Y
		g.mdangle = math.Atan2(dy, dx)
	}

	if ebiten.IsMouseButtonPressed(ebiten.MouseButtonLeft) {

		if g.mdown {
			mx, my := ebiten.CursorPosition()

			dx := float64(mx) - g.flask.GetPosition().X
			dy := float64(my) - g.flask.GetPosition().Y
			angle := math.Atan2(dy, dx)

			g.flask.SetAngle(g.mfangle + (angle - g.mdangle))
		}
	}

	if inpututil.IsMouseButtonJustReleased(ebiten.MouseButtonLeft) {
		g.mdown = false

		mx, my := ebiten.CursorPosition()

		dx := float64(mx) - g.flask.GetPosition().X
		dy := float64(my) - g.flask.GetPosition().Y
		angle := math.Atan2(dy, dx)

		g.mfangle = g.mfangle + (angle - g.mdangle)
	}

	if inpututil.IsKeyJustPressed(ebiten.KeyM) {
		g.flask.ToggleBoundaryMask()
	}
}

func (g *Game) UpdateFlask() {
	g.flask.Update()
}

func (g *Game) RenderFlask(img *ebiten.Image) {

	g.flask.Draw()

	angle := g.flask.GetAngle()
	dim := g.flask.GetDimensions()

	// //TODO: use flask position for rendering, not screen
	pos := g.flask.GetPosition()

	op := &ebiten.DrawImageOptions{}
	op.GeoM.Translate(-dim.X/2, -dim.Y/2)
	op.GeoM.Rotate(angle)
	op.GeoM.Scale(2, 2)
	op.GeoM.Translate(pos.X, pos.Y)

	img.DrawImage(g.flask.GetSprite(), op)

}