Text Center & Scroll > 2D

package main

import (
	rl "github.com/gen2brain/raylib-go/raylib"
)

/* MORE RAYLIB GO EXAMPLES ARE AVAILABLE HERE:

https://github.com/unklnik/raylib-go-more-examples

*/

var (
	cntr                     rl.Vector2                    // SCREEN CENTER
	txtsizes                 = []int32{10, 20, 30, 40, 50} // FONT SIZES SLICE INT32
	currentSize              = 2                           // SET CURRENT SIZE
	txtMoveState             int                           // STATE OF MOTION
	txtx, txty, txt2x, txt2y int32                         // X & Y POSITIONS OF TEXT
	txt, txt2                string                        // TXT STRINGS
)

func main() {

	rl.InitWindow(0, 0, "text center & scroll - raylib go - https://github.com/unklnik/raylib-go-more-examples")
	scrW, scrH := rl.GetScreenWidth(), rl.GetScreenHeight() // GET SCREEN SIZES
	rl.SetWindowSize(scrW, scrH)                            // SET WINDOW SIZE

	//rl.ToggleFullscreen() // UNCOMMENT IF YOU HAVE DISPLAY ISSUES WITH OVERLAPPING WINDOW BARS

	cntr = rl.NewVector2(float32(scrW/2), float32(scrH/2)) // SET SCREEN CENTER

	makeTXT() // SEE FUNCTION END OF CODE

	camera := rl.Camera2D{} // DEFINES THE CAMERA
	camera.Zoom = 1.0       //SETS CAMERA ZOOM

	rl.SetTargetFPS(60) // NUMBER OF FRAMES DRAWN IN A SECOND

	for !rl.WindowShouldClose() {

		if rl.IsKeyPressed(rl.KeyTab) { // CHANGES TEXT SIZE
			currentSize++
			if currentSize == len(txtsizes) { // REACH END OF SLICE RETURN TO ZERO
				currentSize = 0
			}
			makeTXT()
		}

		if rl.IsKeyPressed(rl.KeySpace) { // CHANGE MOVE STATE
			txtMoveState++
			if txtMoveState > 2 { // REACH END OF MOVE STATES RETURN TO ZERO
				txtMoveState = 0
				makeTXT()
			}
		}

		switch txtMoveState {
		case 2: //UP
			txty -= 4 // -Y VALUE MOVES UP

			// Y LESS THAN ZERO (TOP OF SCREEN) RETURN TO BOTTOM (SCREEN HEIGHT)
			if txty < 0 {
				txty = int32(scrH)
			}
			txt2y -= 4
			if txt2y < 0 {
				txt2y = int32(scrH)
			}
		case 1: // RIGHT LEFT
			txtx += 4                                            // MOVE TOP TEXT RIGHT
			txtlen := rl.MeasureText(txt, txtsizes[currentSize]) // MEASURES LENGTH OF TEXT

			// X LARGER THAN SCREEN WIDTH RETURN TO ZERO - TEXT LENGTH
			if txtx > int32(scrW) {
				txtx = -txtlen
			}
			txt2x -= 4 // MOVE BOTTOM TEXT LEFT
			txtlen = rl.MeasureText(txt2, txtsizes[currentSize])
			if txt2x+txtlen < 0 { // X SMALLER THAN ZERO MOVE TO SCREEN WIDTH + TEXT LENGTH
				txt2x = int32(scrW) + txtlen
			}
		}

		rl.BeginDrawing()

		rl.ClearBackground(rl.Black)

		rl.BeginMode2D(camera)

		rl.DrawText(txt, txtx, txty, txtsizes[currentSize], rl.White)    // DRAW TOP TEXT
		rl.DrawText(txt2, txt2x, txt2y, txtsizes[currentSize], rl.White) // DRAW BOTTOM TEXT

		rl.EndMode2D()

		rl.EndDrawing()
	}

	rl.CloseWindow()
}
func makeTXT() {

	txt = "This is a text message, press SPACE to scoll"

	txtlen := rl.MeasureText(txt, txtsizes[currentSize]) // MEASURES LENGTH OF TEXT
	txtx = int32(cntr.X) - txtlen/2                      // X = CENTER - HALF TEXT LENGTH > CENTERS TEXT
	txty = int32(cntr.Y) - txtsizes[currentSize]         // Y = CENTER - TEXT SIZE

	txt2 = "Press TAB to change text size"
	txtlen = rl.MeasureText(txt2, txtsizes[currentSize]) // MEASURES LENGTH OF TEXT
	txt2x = int32(cntr.X) - txtlen/2
	txt2y = int32(cntr.Y) + txtsizes[currentSize]

}