New example : Custom Frame Control

examples/core/custom_frame_control/main.go

@@ -0,0 +1,131 @@
+package main
+
+/*******************************************************************************************
+*
+*   raylib [core] example - custom frame control
+*
+*   NOTE: WARNING: This is an example for advanced users willing to have full control over
+*   the frame processes. By default, EndDrawing() calls the following processes:
+*       1. Draw remaining batch data: rlDrawRenderBatchActive()
+*       2. SwapScreenBuffer()
+*       3. Frame time control: WaitTime()
+*       4. PollInputEvents()
+*
+*   To avoid steps 2, 3 and 4, flag SUPPORT_CUSTOM_FRAME_CONTROL can be enabled in
+*   config.h (it requires recompiling raylib). This way those steps are up to the user.
+*
+*   Note that enabling this flag invalidates some functions:
+*       - GetFrameTime()
+*       - SetTargetFPS()
+*       - GetFPS()
+*
+*   Example originally created with raylib 4.0, last time updated with raylib 4.0
+*
+*   Example licensed under an unmodified zlib/libpng license, which is an OSI-certified,
+*   BSD-like license that allows static linking with closed source software
+*
+*   Copyright (c) 2021-2024 Ramon Santamaria (@raysan5)
+*
+********************************************************************************************/
+
+import (
+	"fmt"
+
+	rl "github.com/gen2brain/raylib-go/raylib"
+)
+
+const (
+	screenWidth  = 800
+	screenHeight = 450
+)
+
+func main() {
+	rl.InitWindow(screenWidth, screenHeight, "raylib [core] example - Custom Frame Control")
+
+	previousTime := rl.GetTime()
+	currentTime := 0.0
+	updateDrawTime := 0.0
+	waitTime := 0.0
+	deltaTime := 0.0
+
+	timeCounter := 0.0
+	position := 0.0
+	pause := false
+
+	targetFPS := 60
+
+	for !rl.WindowShouldClose() {
+		rl.PollInputEvents() // Poll input events (SUPPORT_CUSTOM_FRAME_CONTROL)
+
+		if rl.IsKeyPressed(rl.KeySpace) {
+			pause = !pause
+		}
+		if rl.IsKeyPressed(rl.KeyUp) {
+			targetFPS += 20
+		} else if rl.IsKeyPressed(rl.KeyDown) {
+			targetFPS -= 20
+		}
+
+		if targetFPS < 0 {
+			targetFPS = 0
+		}
+
+		if !pause {
+			position += 200 * deltaTime // We move at 200 pixels per second
+			if position >= float64(rl.GetScreenWidth()) {
+				position = 0
+			}
+			timeCounter += deltaTime // We count time (seconds)
+		}
+
+		rl.BeginDrawing()
+		rl.ClearBackground(rl.RayWhite)
+
+		for i := 0; i < rl.GetScreenWidth()/200; i++ {
+			rl.DrawRectangle(200*int32(i), 0, 1, int32(rl.GetScreenHeight()), rl.SkyBlue)
+		}
+
+		rl.DrawCircle(int32(position), int32(rl.GetScreenHeight()/2-25), 50, rl.Red)
+
+		msg := fmt.Sprintf("%03.0f ms", timeCounter*1000)
+		rl.DrawText(msg, int32(position-40), int32(rl.GetScreenHeight()/2-100), 20, rl.Maroon)
+		msg = fmt.Sprintf("PosX: %03.0f", position)
+		rl.DrawText(msg, int32(position-50), int32(rl.GetScreenHeight()/2+40), 20, rl.Black)
+
+		msg = "Circle is moving at a constant 200 pixels/sec,\nindependently of the frame rate."
+		rl.DrawText(msg, 10, 10, 20, rl.DarkGray)
+		msg = "PRESS SPACE to PAUSE MOVEMENT"
+		rl.DrawText(msg, 10, int32(rl.GetScreenHeight()-60), 20, rl.Gray)
+		msg = "PRESS UP | DOWN to CHANGE TARGET FPS"
+		rl.DrawText(msg, 10, int32(rl.GetScreenHeight()-30), 20, rl.Gray)
+		msg = fmt.Sprintf("TARGET FPS: %d", targetFPS)
+		rl.DrawText(msg, int32(rl.GetScreenWidth()-220), 10, 20, rl.Lime)
+		msg = fmt.Sprintf("CURRENT FPS: %d", int(1/deltaTime))
+		rl.DrawText(msg, int32(rl.GetScreenWidth()-220), 40, 20, rl.Lime)
+
+		rl.EndDrawing()
+
+		// NOTE: In case raylib is configured to SUPPORT_CUSTOM_FRAME_CONTROL,
+		// Events polling, screen buffer swap and frame time control must be managed by the user
+
+		rl.SwapScreenBuffer() // We want a fixed frame rate
+
+		currentTime = rl.GetTime()
+		updateDrawTime = currentTime - previousTime
+
+		if targetFPS > 0 { // We want a fixed frame rate
+			waitTime = (1 / float64(targetFPS)) - updateDrawTime
+			if waitTime > 0 {
+				rl.WaitTime(waitTime)
+				currentTime = rl.GetTime()
+				deltaTime = currentTime - previousTime
+			}
+		} else {
+			deltaTime = updateDrawTime
+		}
+
+		previousTime = currentTime
+	}
+
+	rl.CloseWindow()
+}