Draw sin (LWJGL 2)

Main.java

package me.superblaubeere27;

import org.lwjgl.LWJGLException;
import org.lwjgl.input.Keyboard;
import org.lwjgl.opengl.Display;
import org.lwjgl.opengl.DisplayMode;
import org.lwjgl.opengl.GL11;
import org.lwjgl.opengl.PixelFormat;

public class Main {
    private static double TIME;
    private static boolean PAUSE = false;
    private static int STEP_SIZE = 10;

    private void start() {
        try {
            for (DisplayMode availableDisplayMode : Display.getAvailableDisplayModes()) {
                if (availableDisplayMode.getWidth() == 1920 && availableDisplayMode.getHeight() == 1080 && availableDisplayMode.isFullscreenCapable()) {
                    Display.setDisplayMode(availableDisplayMode);
                    Display.setFullscreen(true);
                    break;
                }
            }
            Display.setVSyncEnabled(true);
            Display.setResizable(true);
            Display.setTitle("Sine");
            Display.create(new PixelFormat(0, 8, 0, 8));
        } catch (LWJGLException e) {
            e.printStackTrace();
            System.exit(-1);
        }

        // init OpenGL
        GL11.glMatrixMode(GL11.GL_PROJECTION);
        GL11.glLoadIdentity();
        GL11.glOrtho(0, Display.getWidth(), Display.getHeight(), 0, 1, -1);
        GL11.glMatrixMode(GL11.GL_MODELVIEW);

        while (!Display.isCloseRequested()) {
            // Clear the screen and depth buffer
            GL11.glClear(GL11.GL_COLOR_BUFFER_BIT | GL11.GL_DEPTH_BUFFER_BIT);

            render();

            Display.update();

            update();
        }

        Display.destroy();
    }

    private void update() {
        while (Keyboard.next()) {
            int k = Keyboard.getEventKey() == 0 ? Keyboard.getEventCharacter() + 256 : Keyboard.getEventKey();

            if (Keyboard.getEventKeyState()) {
                if (k == Keyboard.KEY_ADD) {
                    STEP_SIZE++;
                    System.out.println("Stepsize: " + STEP_SIZE);
                }
                if (k == Keyboard.KEY_SUBTRACT) {
                    STEP_SIZE--;
                    System.out.println("Stepsize: " + STEP_SIZE);
                }
                if (k == Keyboard.KEY_PAUSE) {
                    PAUSE = !PAUSE;
                }
            }
        }
    }

    private void render() {
        GL11.glBlendFunc(GL11.GL_SRC_ALPHA, GL11.GL_ONE_MINUS_SRC_ALPHA);
        GL11.glEnable(GL11.GL_BLEND);

        GL11.glColor4f(1.0f, 1.0f, 1.0f, 1.0f);
        GL11.glLineWidth(2.0f);

        GL11.glBegin(GL11.GL_LINE_STRIP);

        TIME = PAUSE ? TIME : System.currentTimeMillis() / 100.0;

        for (int i = 0; i < Display.getWidth(); i += STEP_SIZE) {
            double sin = Math.sin(i / 75.0 + TIME);
            GL11.glVertex2d(i, Display.getHeight() / 2.0 + (sin * Display.getHeight() / 4.0));
        }
        GL11.glEnd();

        GL11.glBegin(GL11.GL_LINE_STRIP);

        for (int i = 0; i < Display.getWidth(); i += STEP_SIZE) {
            double sin = Math.cos(i / 60.0 + TIME);
            GL11.glVertex2d(i, Display.getHeight() / 2.0 + (sin * Display.getHeight() / 4.0));
        }

        GL11.glEnd();
    }

    public static void main(String[] argv) {
        Main quadExample = new Main();
        quadExample.start();
    }
}