GOingTunneling/graphics.go

package main

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

func initializeSDL() {
	if err := sdl.Init(sdl.INIT_EVERYTHING); err != nil {
		panic(err)
	}
}

func setupWindowAndSurface(playerIndex uint8) (*sdl.Window, *sdl.Surface) {
	const windowWidth, windowHeight = 160, 100
	window, err := sdl.CreateWindow(fmt.Sprintf("Tunneler - player %d", playerIndex), sdl.WINDOWPOS_UNDEFINED, sdl.WINDOWPOS_UNDEFINED, windowWidth, windowHeight, sdl.WINDOW_SHOWN|sdl.WINDOW_RESIZABLE)
	if err != nil {
		panic(err)
	}

	logicalSurface, err := sdl.CreateRGBSurface(0, windowWidth, windowHeight, 32, 0, 0, 0, 0)
	if err != nil {
		panic(err)
	}

	return window, logicalSurface
}

func setupMapWindowAndSurface() (*sdl.Window, *sdl.Surface) {
	window, err := sdl.CreateWindow("Tunneler map", sdl.WINDOWPOS_UNDEFINED, sdl.WINDOWPOS_UNDEFINED, int32(serverConfig.MapWidth), int32(serverConfig.MapWidth), sdl.WINDOW_SHOWN|sdl.WINDOW_RESIZABLE)
	if err != nil {
		panic(err)
	}

	logicalSurface, err := sdl.CreateRGBSurface(0, int32(serverConfig.MapWidth), int32(serverConfig.MapWidth), 32, 0, 0, 0, 0)
	if err != nil {
		panic(err)
	}

	return window, logicalSurface
}

func setupPlaySurface() (*sdl.Surface, *sdl.Rect, *sdl.Rect) {
	playSurface, err := sdl.CreateRGBSurface(0, config.CameraW, config.CameraH, 32, 0, 0, 0, 0)
	if err != nil {
		panic(err)
	}
	playSurfaceRect := &sdl.Rect{X: 0, Y: 0, W: config.CameraW, H: config.CameraH}
	playSurfaceTargetRect := &sdl.Rect{X: 42, Y: 0, W: config.CameraW, H: config.CameraH}

	return playSurface, playSurfaceRect, playSurfaceTargetRect
}

func setupHUDSurface() (*sdl.Surface, *sdl.Rect, *sdl.Rect) {
	HUDSurface, err := sdl.CreateRGBSurface(0, 112, 25, 32, 0, 0, 0, 0)
	if err != nil {
		panic(err)
	}
	HUDSurfaceRect := &sdl.Rect{X: 0, Y: 0, W: 112, H: 25}
	HUDSurfaceTargetRect := &sdl.Rect{X: 24, Y: config.CameraH, W: 112, H: 25}

	return HUDSurface, HUDSurfaceRect, HUDSurfaceTargetRect
}

func handleEvents(window *sdl.Window, logicalSurface *sdl.Surface) bool {
	for event := sdl.PollEvent(); event != nil; event = sdl.PollEvent() {
		switch e := event.(type) {
		case *sdl.QuitEvent:
			return false
		case *sdl.WindowEvent:
			if e.Event == sdl.WINDOWEVENT_RESIZED {
				handleWindowResize(window, logicalSurface)
			}
		}
	}
	return true
}

func handleWindowResize(window *sdl.Window, logicalSurface *sdl.Surface) {
	windowSurface, err := window.GetSurface()
	if err != nil {
		panic(err)
	}

	windowWidth, windowHeight := windowSurface.W, windowSurface.H

	aspectRatio := float64(logicalSurface.W) / float64(logicalSurface.H)
	newWidth := windowWidth
	newHeight := int32(float64(windowWidth) / aspectRatio)

	if newHeight > windowHeight {
		newHeight = windowHeight
		newWidth = int32(float64(windowHeight) * aspectRatio)
	}

	letterboxX := (windowWidth - newWidth) / 2
	letterboxY := (windowHeight - newHeight) / 2

	srcRect := &sdl.Rect{X: 0, Y: 0, W: logicalSurface.W, H: logicalSurface.H}
	dstRect := &sdl.Rect{X: letterboxX, Y: letterboxY, W: newWidth, H: newHeight}

	_ = logicalSurface.BlitScaled(srcRect, windowSurface, dstRect)
	_ = window.UpdateSurface()
}

func adjustWindow(window *sdl.Window, logicalSurface *sdl.Surface) {
	// Get window surface and handle any errors
	windowSurface, err := window.GetSurface()
	if err != nil {
		panic(err)
	}

	// Retrieve window dimensions
	windowWidth, windowHeight := windowSurface.W, windowSurface.H

	// Calculate aspect ratio
	logicalAspectRatio := float64(logicalSurface.W) / float64(logicalSurface.H)
	windowAspectRatio := float64(windowWidth) / float64(windowHeight)

	var newWidth, newHeight int32
	if windowAspectRatio > logicalAspectRatio {
		// Window is wider than logical surface
		newHeight = windowHeight
		newWidth = int32(float64(windowHeight) * logicalAspectRatio)
	} else {
		// Window is taller or equal in aspect ratio
		newWidth = windowWidth
		newHeight = int32(float64(windowWidth) / logicalAspectRatio)
	}

	// Calculate letterbox positions
	letterboxX := (windowWidth - newWidth) / 2
	letterboxY := (windowHeight - newHeight) / 2

	// Fill background
	_ = windowSurface.FillRect(nil, sdl.MapRGBA(logicalSurface.Format, 80, 20, 10, 255))

	// Set source and destination rectangles
	srcRect := &sdl.Rect{X: 0, Y: 0, W: logicalSurface.W, H: logicalSurface.H}
	dstRect := &sdl.Rect{X: letterboxX, Y: letterboxY, W: newWidth, H: newHeight}

	// Perform the scaled blit
	_ = logicalSurface.BlitScaled(srcRect, windowSurface, dstRect)

	// Update the window surface
	_ = window.UpdateSurface()
}