Better frame scheduling

src/main/kotlin/ru/dbotthepony/kstarbound/Main.kt

@@ -242,8 +242,8 @@ fun main() {
 		//client.camera.pos.y = ent.position.y.toFloat()
 
 		client.camera.pos += Vector2f(
-			(if (client.input.KEY_LEFT_DOWN || client.input.KEY_A_DOWN) -client.frameRenderTime.toFloat() * 32f / client.settings.zoom else 0f) + (if (client.input.KEY_RIGHT_DOWN || client.input.KEY_D_DOWN) client.frameRenderTime.toFloat() * 32f / client.settings.zoom else 0f),
+			(if (client.input.KEY_LEFT_DOWN || client.input.KEY_A_DOWN) -Starbound.TICK_TIME_ADVANCE.toFloat() * 32f / client.settings.zoom else 0f) + (if (client.input.KEY_RIGHT_DOWN || client.input.KEY_D_DOWN) Starbound.TICK_TIME_ADVANCE.toFloat() * 32f / client.settings.zoom else 0f),
-			(if (client.input.KEY_UP_DOWN || client.input.KEY_W_DOWN) client.frameRenderTime.toFloat() * 32f / client.settings.zoom else 0f) + (if (client.input.KEY_DOWN_DOWN || client.input.KEY_S_DOWN) -client.frameRenderTime.toFloat() * 32f / client.settings.zoom else 0f)
+			(if (client.input.KEY_UP_DOWN || client.input.KEY_W_DOWN) Starbound.TICK_TIME_ADVANCE.toFloat() * 32f / client.settings.zoom else 0f) + (if (client.input.KEY_DOWN_DOWN || client.input.KEY_S_DOWN) -Starbound.TICK_TIME_ADVANCE.toFloat() * 32f / client.settings.zoom else 0f)
 		)
 
 		//println(client.camera.velocity.toDoubleVector() * client.frameRenderTime * 0.1)

src/main/kotlin/ru/dbotthepony/kstarbound/Starbound.kt

@@ -85,6 +85,8 @@ import ru.dbotthepony.kstarbound.util.set
 import ru.dbotthepony.kstarbound.util.traverseJsonPath
 import java.io.*
 import java.text.DateFormat
+import java.time.Duration
+import java.time.temporal.ChronoUnit
 import java.util.function.BiConsumer
 import java.util.function.BinaryOperator
 import java.util.function.Function
@@ -95,7 +97,8 @@ import kotlin.collections.ArrayList
 import kotlin.random.Random
 
 object Starbound : ISBFileLocator {
-	const val TICK_TIME_ADVANCE = 1.0 / 60.0
+	const val TICK_TIME_ADVANCE = 0.01666666666666664
+	const val TICK_TIME_ADVANCE_NANOS = 16_666_666L
 
 	// currently it saves only 4 megabytes of ram on pretty big modpack
 	// Hrm.

src/main/kotlin/ru/dbotthepony/kstarbound/client/StarboundClient.kt

@@ -49,7 +49,6 @@ import ru.dbotthepony.kstarbound.client.world.ClientWorld
 import ru.dbotthepony.kstarbound.defs.image.Image
 import ru.dbotthepony.kstarbound.math.roundTowardsNegativeInfinity
 import ru.dbotthepony.kstarbound.math.roundTowardsPositiveInfinity
-import ru.dbotthepony.kstarbound.util.JVMTimeSource
 import ru.dbotthepony.kstarbound.util.formatBytesShort
 import ru.dbotthepony.kstarbound.world.LightCalculator
 import ru.dbotthepony.kstarbound.world.api.ICellAccess
@@ -742,26 +741,41 @@ class StarboundClient : Closeable {
 		blendFunc = BlendFunc.MULTIPLY_WITH_ALPHA
 	}
 
-	var frameRenderTime = 0.0
+	// nanoseconds
+	var frameRenderTime = 0L
 		private set
 
-	private var lastRender = JVMTimeSource.INSTANCE.seconds
+	private var nextRender = System.nanoTime()
-	val framesPerSecond get() = if (frameRenderTime == 0.0) 1.0 else 1.0 / frameRenderTime
+	private val frameRenderTimes = LongArray(60) { 1L }
-
-	private val frameRenderTimes = DoubleArray(60) { 1.0 }
 	private var frameRenderIndex = 0
+	private val renderWaitTimes = LongArray(60) { 1L }
+	private var renderWaitIndex = 0
+	private var lastRender = System.nanoTime()
 
-	val averageFramesPerSecond: Double get() {
+	val averageRenderWait: Double get() {
 		var sum = 0.0
 
-		for (value in frameRenderTimes) {
+		for (value in renderWaitTimes)
 			sum += value
-		}
 
 		if (sum == 0.0)
 			return 0.0
 
-		return frameRenderTimes.size / sum
+		sum /= 1_000_000_000.0
+		return sum / renderWaitTimes.size
+	}
+
+	val averageRenderTime: Double get() {
+		var sum = 0.0
+
+		for (value in frameRenderTimes)
+			sum += value
+
+		if (sum == 0.0)
+			return 0.0
+
+		sum /= 1_000_000_000.0
+		return sum / frameRenderTimes.size
 	}
 
 	val settings = ClientSettings()
@@ -828,15 +842,24 @@ class StarboundClient : Closeable {
 	fun renderFrame(): Boolean {
 		ensureSameThread()
 
-		val diff = JVMTimeSource.INSTANCE.seconds - lastRender
+		var diff = nextRender - System.nanoTime()
+		var yields = 0
 
-		if (diff < Starbound.TICK_TIME_ADVANCE)
+		// try to sleep until next frame as precise as possible
-			LockSupport.parkNanos(((Starbound.TICK_TIME_ADVANCE - diff) * 1_000_000_000.0).toLong())
+		while (diff > 0L) {
+			if (diff >= 1_500_000L) {
+				LockSupport.parkNanos(1_000_000L)
+			} else {
+				Thread.yield()
+				yields++
+			}
 
-		frameRenderTime = JVMTimeSource.INSTANCE.seconds - lastRender
+			diff = nextRender - System.nanoTime()
-		frameRenderTimes[++frameRenderIndex % frameRenderTimes.size] = frameRenderTime
+		}
-		lastRender = JVMTimeSource.INSTANCE.seconds
 
+		val mark = System.nanoTime()
+
+		try {
 			if (GLFW.glfwWindowShouldClose(window)) {
 				close()
 				return false
@@ -974,8 +997,9 @@ class StarboundClient : Closeable {
 
 			val runtime = Runtime.getRuntime()
 
-		font.render("FPS: ${(averageFramesPerSecond * 100f).toInt() / 100f}", scale = 0.4f)
+			font.render("Latency: ${(averageRenderWait * 1_00000.0).toInt() / 100f}ms", scale = 0.4f)
-		font.render("JVM Heap: ${formatBytesShort(runtime.totalMemory() - runtime.freeMemory())}", y = font.lineHeight * 0.5f, scale = 0.4f)
+			font.render("Frame: ${(averageRenderTime * 1_00000.0).toInt() / 100f}ms", y = font.lineHeight * 0.6f, scale = 0.4f)
+			font.render("JVM Heap: ${formatBytesShort(runtime.totalMemory() - runtime.freeMemory())}", y = font.lineHeight * 1.2f, scale = 0.4f)
 
 			GLFW.glfwSwapBuffers(window)
 			GLFW.glfwPollEvents()
@@ -986,6 +1010,13 @@ class StarboundClient : Closeable {
 			cleanup()
 
 			return true
+		} finally {
+			frameRenderTime = System.nanoTime() - mark
+			frameRenderTimes[++frameRenderIndex % frameRenderTimes.size] = frameRenderTime
+			renderWaitTimes[++renderWaitIndex % renderWaitTimes.size] = System.nanoTime() - lastRender
+			lastRender = System.nanoTime()
+			nextRender = mark + Starbound.TICK_TIME_ADVANCE_NANOS
+		}
 	}
 
 	fun onTermination(lambda: () -> Unit) {