blooblib/run.go

package bloob

import (
	_ "embed"
	"fmt"
	"github.com/veandco/go-sdl2/sdl"
	"time"
)

type Runnable interface {
	Init(settings *Settings)
	Render(screen *Image)
	Update(bloob *Bloob)
}

type Settings struct {
	WindowSize Vec2i
	Scale      int
	TargetFps  int
	Title      string
}

type Bloob struct {
	MousePos Vec2i
	Cursor   *Image
}

var DefaultCursor *Image

//go:embed "cursor.png"
var defaultCursorBytes []byte

func Run(game Runnable) {
	_ = sdl.Init(sdl.INIT_EVERYTHING)
	defer sdl.Quit()

	settings := Settings{
		WindowSize: Vec2i{X: 640, Y: 360},
		Scale:      3,
		TargetFps:  60,
		Title:      "Blooblib",
	}

	if DefaultCursor == nil {
		DefaultCursor = LoadImageBytes(defaultCursorBytes)
	}

	bloob := Bloob{
		Cursor: DefaultCursor,
	}

	game.Init(&settings)

	window, _ := sdl.CreateWindow(
		settings.Title,
		sdl.WINDOWPOS_CENTERED,
		sdl.WINDOWPOS_CENTERED,
		int32(settings.WindowSize.X*settings.Scale),
		int32(settings.WindowSize.Y*settings.Scale),
		sdl.WINDOW_SHOWN,
	)
	surface, _ := window.GetSurface()
	windowImage := NewImageFromPointer(surface.Data(), MulScalar(settings.WindowSize, settings.Scale))
	screen := NewImage(settings.WindowSize)
	screen.Alpha = false

	sdl.ShowCursor(sdl.DISABLE)

	_ = window.UpdateSurface()

	lastSecond := time.Now()
	framesSinceLastSecond := 0

	targetFPS := 60
	frameDuration := time.Second / time.Duration(targetFPS)
	lastFrame := lastSecond

	running := true
	for running {
		for event := sdl.PollEvent(); event != nil; event = sdl.PollEvent() {
			switch event := event.(type) {
			case sdl.QuitEvent:
				running = false
				break
			case sdl.MouseMotionEvent:
				bloob.MousePos.X = int(event.X) / settings.Scale
				bloob.MousePos.Y = int(event.Y) / settings.Scale
				break
			}
		}
		now := time.Now()
		delta := now.Sub(lastSecond)
		if delta.Seconds() >= 1.0 {
			fmt.Printf("FPS: %5d | mspf: %f\n", framesSinceLastSecond, 1000.0/float32(framesSinceLastSecond))
			framesSinceLastSecond = 0
			lastSecond = lastSecond.Add(time.Second)
		}

		delta2 := now.Sub(lastFrame)
		if delta2 >= frameDuration {
			game.Update(&bloob)
			game.Render(screen)
			if bloob.Cursor != nil {
				screen.Draw(bloob.Cursor, bloob.MousePos)
			}
			windowImage.DrawUpscale(screen)
			framesSinceLastSecond += 1
			lastFrame = lastFrame.Add(frameDuration)
		}
		_ = window.UpdateSurface()
	}

}