Refactor into cmd, engine and game packages to make the code more clear

engine/render/render.go

@@ -0,0 +1,83 @@
+// Package render provides a tile-based rendering system inspired by the NES 8-bit graphics API.
+//
+// This is not an emulator, but rather a rendering layer designed to mimic the style
+// and constraints of 8-bit consoles. It exposes a simplified API for tile-based drawing,
+// allowing rendering of graphics in a grid-based fashion similar to early consoles.
+//
+// The render target is an off-screen texture with a fixed resolution of 224×288 pixels,
+// divided into 8x8 pixel tiles:
+//
+//   - Screen dimensions: 28 tiles wide, 36 tiles high
+//   - Tile size: 8x8 pixels
+//
+// This off-screen texture is then scaled to fit the actual window size when presented to the screen.
+// Rendering is double-buffered and must follow a Begin/Draw/End pattern each frame.
+package render
+
+import rl "github.com/gen2brain/raylib-go/raylib"
+
+// target is the off-screen render target where all drawing operations are performed.
+// It has a fixed resolution of WIDTHxHEIGHT and is later scaled to the window size.
+var target rl.RenderTexture2D
+
+// Init initializes the rendering system.
+//
+// It creates an off-screen render texture with the fixed resolution defined by WIDTH and HEIGHT.
+// This texture is where all tiles and game graphics are drawn before being scaled and presented.
+func Init() {
+	target = rl.LoadRenderTexture(WIDTH, HEIGHT)
+}
+
+// Exit shuts down the rendering system.
+//
+// It unloads the render texture and frees any associated GPU resources.
+// This should be called before the application exits.
+func Exit() {
+	rl.UnloadRenderTexture(target)
+}
+
+// Begin prepares the rendering system for a new frame.
+//
+// It binds the off-screen texture target and clears it to a black background.
+// All tile drawing operations (e.g., DrawTile) should occur after Begin() and
+// before End().
+func Begin() {
+	// Bind texture so that all draw calls after are applied to target texture
+	rl.BeginTextureMode(target)
+	// Clear background
+	rl.ClearBackground(rl.Black)
+}
+
+// End finalizes the current frame and displays it on the screen.
+//
+// It ends the off-screen drawing session and stretches the texture target
+// to fill the window. This function must be called after all drawing is done.
+func End() {
+	// End drawing to the texture target.
+	rl.EndTextureMode()
+
+	// Begin drawing to screen buffer.
+	rl.BeginDrawing()
+
+	// Define source rectangle (flip vertically to match coordinate systems).
+	src := rl.Rectangle{
+		X:      0,
+		Y:      0,
+		Width:  float32(target.Texture.Width),
+		Height: -float32(target.Texture.Height),
+	}
+
+	// Define destination rectangle (window).
+	dest := rl.Rectangle{
+		X:      0,
+		Y:      0,
+		Width:  float32(rl.GetScreenWidth()),
+		Height: float32(rl.GetScreenHeight()),
+	}
+
+	// Blit the off-screen texture to the screen.
+	rl.DrawTexturePro(target.Texture, src, dest, rl.Vector2Zero(), 0.0, rl.White)
+
+	// End drawing to screen.
+	rl.EndDrawing()
+}