perf: add reproducible sprite benchmarks

Co-authored-by: codegirl007 <s.raide@gmail.com>

benchmarks/draw_sprite/main.odin

@@ -0,0 +1,102 @@
+package main
+
+import "core:fmt"
+import "core:os"
+import eng "pkg:engine"
+import sdl "vendor:sdl3"
+
+PERF_ITERATIONS :: #config(PERF_ITERATIONS, 2_000_000)
+PERF_WARMUP     :: #config(PERF_WARMUP, 10_000)
+PERF_TRIALS     :: #config(PERF_TRIALS, 7)
+
+@(private)
+median :: proc(values: []f64) -> f64 {
+	for i in 1 ..< len(values) {
+		value := values[i]
+		j := i
+		for j > 0 {
+			if values[j - 1] <= value do break
+			values[j] = values[j - 1]
+			j -= 1
+		}
+		values[j] = value
+	}
+
+	middle := len(values) / 2
+	if len(values) & 1 == 1 do return values[middle]
+	return (values[middle - 1] + values[middle]) / 2
+}
+
+@(private)
+run_draws :: proc(app: ^eng.App, sprite: ^eng.Sprite, iterations: int) -> u64 {
+	clear(&app.draw_list)
+	start := sdl.GetTicksNS()
+	for i in 0 ..< iterations {
+		if len(app.draw_list) >= eng.MAX_SPRITES {
+			clear(&app.draw_list)
+		}
+
+		// Vary an input so optimized builds cannot hoist the draw calculations.
+		sprite.position.x = f32(i & 1023)
+		eng.draw_sprite(app, sprite)
+	}
+	return sdl.GetTicksNS() - start
+}
+
+main :: proc() {
+	#assert(PERF_ITERATIONS > 0)
+	#assert(PERF_WARMUP > 0)
+	#assert(PERF_TRIALS > 0)
+
+	file_data, err := os.read_entire_file(
+		"assets_baked/characters/toad/toad.char.json",
+		context.allocator,
+	)
+	if err != nil {
+		fmt.eprintfln("benchmark asset read failed: %v", err)
+		return
+	}
+	defer delete(file_data)
+
+	def, ok := eng.parse_char_def(file_data)
+	if !ok do return
+
+	data := eng.Character_Data {
+		def     = def,
+		texture = cast(^sdl.GPUTexture)uintptr(1),
+		width   = 1911,
+		height  = 1526,
+	}
+	app := eng.App {
+		cmd               = cast(^sdl.GPUCommandBuffer)uintptr(1),
+		swapchain_texture = cast(^sdl.GPUTexture)uintptr(2),
+		swapchain_w       = 800,
+		swapchain_h       = 600,
+		camera             = eng.camera_default(),
+		draw_list          = make(
+			[dynamic]eng.Queued_Sprite,
+			0,
+			eng.MAX_SPRITES,
+		),
+	}
+	defer delete(app.draw_list)
+
+	sprite := eng.spawn_sprite(&data, {400, 400}, "walk", 4)
+	_ = run_draws(&app, &sprite, PERF_WARMUP)
+
+	samples: [PERF_TRIALS]f64
+	fmt.printfln(
+		"benchmark=draw_sprite iterations=%d warmup=%d trials=%d sprites_per_queue=%d",
+		PERF_ITERATIONS,
+		PERF_WARMUP,
+		PERF_TRIALS,
+		eng.MAX_SPRITES,
+	)
+	for trial in 0 ..< PERF_TRIALS {
+		elapsed := run_draws(&app, &sprite, PERF_ITERATIONS)
+		samples[trial] = f64(elapsed) / f64(PERF_ITERATIONS)
+		fmt.printfln("trial=%d ns_per_draw=%.3f", trial + 1, samples[trial])
+	}
+
+	fmt.printfln("median_ns_per_draw=%.3f", median(samples[:]))
+}