abstracting to engine package

engine/app.odin

@@ -0,0 +1,56 @@
+package engine
+
+import "core:fmt"
+import sdl "vendor:sdl3"
+
+App :: struct {
+	window:   ^sdl.Window,
+	renderer: ^sdl.Renderer,
+}
+
+init :: proc(app: ^App, title: cstring, width, height: i32) -> bool {
+	if !sdl.Init({.VIDEO}) {
+		fmt.eprintfln("SDL_Init failed: %s", sdl.GetError())
+		return false
+	}
+
+	if !sdl.CreateWindowAndRenderer(title, width, height, {}, &app.window, &app.renderer) {
+		fmt.eprintfln("CreateWindowAndRenderer failed: %s", sdl.GetError())
+		return false
+	}
+
+	return true
+}
+
+shutdown :: proc(app: ^App) {
+	if app.renderer != nil do sdl.DestroyRenderer(app.renderer)
+	if app.window != nil do sdl.DestroyWindow(app.window)
+
+	sdl.Quit()
+	app^ = {}
+}
+
+pump_events :: proc() -> bool {
+	event: sdl.Event
+
+	for sdl.PollEvent(&event) {
+		if event.type == .QUIT {
+			return false
+		}
+	}
+
+	return true
+}
+
+begin_frame :: proc(app: ^App, r: u8 = 30, g: u8 = 30, b: u8 = 40, a: u8 = 255) {
+	sdl.SetRenderDrawColor(app.renderer, r, g, b, a)
+	sdl.RenderClear(app.renderer)
+}
+
+end_frame :: proc(app: ^App) {
+	sdl.RenderPresent(app.renderer)
+}
+
+renderer :: proc(app: ^App) -> ^sdl.Renderer {
+	return app.renderer
+}

engine/character_data.odin

@@ -0,0 +1,108 @@
+package engine
+
+import "core:encoding/json"
+import "core:fmt"
+import "core:os"
+import "core:path/filepath"
+import "core:strings"
+import sdl "vendor:sdl3"
+
+Frame_Def :: struct {
+	rect:        [4]int,
+	source_size: [2]int,
+	trim_offset: [2]int,
+}
+
+Clip_Def :: struct {
+	loop:   bool,
+	fps:    f32,
+	frames: []Frame_Def,
+}
+
+Char_Def :: struct {
+	version:         int,
+	id:              string,
+	atlas:           string,
+	pixels_per_unit: f32,
+	pivot:           [2]f32,
+	clips:           map[string]Clip_Def,
+}
+
+Character_Data :: struct {
+	def:     Char_Def,
+	texture: ^sdl.Texture,
+}
+
+load_character_data :: proc(
+	renderer: ^sdl.Renderer,
+	character_json_path: string,
+) -> (
+	Character_Data,
+	bool,
+) {
+	file_data, read_err := os.read_entire_file(character_json_path, context.allocator)
+	if read_err != nil {
+		fmt.eprintfln("failed to read %s: %v", character_json_path, read_err)
+		return {}, false
+	}
+
+	defer delete(file_data)
+
+	out: Character_Data
+	if err := json.unmarshal(file_data, &out.def); err != nil {
+		fmt.eprintfln("json unmarshal failed: %v", err)
+		return {}, false
+	}
+
+	// filepath.dir returns a substring of the path — do NOT delete it
+	dir := filepath.dir(character_json_path)
+
+	atlas_path, join_err := filepath.join({dir, out.def.atlas})
+	if join_err != nil {
+		fmt.eprintfln("atlas join failed: %v", join_err)
+		return {}, false
+	}
+
+	defer delete(atlas_path)
+
+	c_path := strings.clone_to_cstring(atlas_path)
+	defer delete(c_path)
+
+	surface := sdl.LoadPNG(c_path)
+	if surface == nil {
+		fmt.eprintfln("LoadPNG failed: %s", sdl.GetError())
+		return {}, false
+	}
+	defer sdl.DestroySurface(surface)
+
+	out.texture = sdl.CreateTextureFromSurface(renderer, surface)
+	if out.texture == nil {
+		fmt.eprintfln("CreateTextureFromSurface failed: %s", sdl.GetError())
+		return {}, false
+	}
+	sdl.SetTextureScaleMode(out.texture, .NEAREST)
+	return out, true
+}
+
+destroy_character_data :: proc(data: ^Character_Data) {
+	if data.texture != nil {
+		sdl.DestroyTexture(data.texture)
+	}
+	data^ = {}
+}
+
+character_frame_rect :: proc(
+	data: ^Character_Data,
+	clip_name: string,
+	frame_index: int,
+) -> (
+	rect: [4]int,
+	ok: bool,
+) {
+	clip, found := data.def.clips[clip_name]
+	if !found || frame_index < 0 || frame_index >= len(clip.frames) {
+		return {}, false
+	}
+
+	return clip.frames[frame_index].rect, true
+}

engine/sprite.odin

@@ -0,0 +1,51 @@
+package engine
+
+import sdl "vendor:sdl3"
+
+Vec2 :: [2]f32
+
+Sprite :: struct {
+	data:     ^Character_Data,
+	position: Vec2,
+	clip:     string,
+	frame:    int,
+}
+
+spawn_sprite :: proc(
+	data: ^Character_Data,
+	position: Vec2,
+	clip: string = "idle",
+	frame: int = 0,
+) -> Sprite {
+	return Sprite{data = data, position = position, clip = clip, frame = frame}
+}
+
+// stubbed for later
+update_sprite :: proc(sprite: ^Sprite, dt: f32) {
+	_ = sprite
+	_ = dt
+}
+
+draw_sprite :: proc(renderer: ^sdl.Renderer, sprite: ^Sprite) {
+	assert(sprite.data != nil)
+	rect, ok := character_frame_rect(sprite.data, sprite.clip, sprite.frame)
+	if !ok {
+		return
+	}
+
+	w := f32(rect[2])
+	h := f32(rect[3])
+	dst := sdl.FRect {
+		x = sprite.position.x - w * 0.5,
+		y = sprite.position.y - h,
+		w = w,
+		h = h,
+	}
+	src := sdl.FRect {
+		x = f32(rect[0]),
+		y = f32(rect[1]),
+		w = w,
+		h = h,
+	}
+	sdl.RenderTexture(renderer, sprite.data.texture, &src, &dst)
+}