Anti-aliasing in LWJGL 3

Question

I am trying to draw an anti-aliased square in LWJGL 3. I am only drawing 2D sprites and I'm not drawing textures. This answer to a similar question reveals that anti-aliasing in LWJGL must be achieved with post-processing, but does not actually give an example or any resources on how to do this. Below is an example of some code. This is what is rendered on screen from the code. Please tell me how to modify this code to make anti-aliasing possible.

import java.nio.FloatBuffer;
import java.nio.IntBuffer;

import org.lwjgl.*;
import org.lwjgl.glfw.*;
import org.lwjgl.opengl.*;

import static org.lwjgl.glfw.GLFW.*;
import static org.lwjgl.opengl.GL11.*;
import static org.lwjgl.system.MemoryUtil.*;
import static org.lwjgl.opengl.GL15.*;

public class LWJGLTest {

    private GLFWErrorCallback errorCallback;
    private GLFWKeyCallback   keyCallback;

    private long window;

    public void run() {

        try {
            init();
            loop();

            glfwDestroyWindow(window);
            keyCallback.release();
        } finally {

            glfwTerminate();
            errorCallback.release();
        }
    }

    int WIDTH = 300;
    int HEIGHT = 300;

    private void init() {

        glfwSetErrorCallback(errorCallback = GLFWErrorCallback.createPrint(System.err));

        if ( glfwInit() != GLFW_TRUE )
            throw new IllegalStateException("Unable to initialize GLFW");

        glfwDefaultWindowHints();
        glfwWindowHint(GLFW_VISIBLE, GLFW_FALSE);
        glfwWindowHint(GLFW_RESIZABLE, GLFW_TRUE);

        window = glfwCreateWindow(WIDTH, HEIGHT, "Hello World!", NULL, NULL);
        if ( window == NULL )
            throw new RuntimeException("Failed to create the GLFW window");

        glfwSetKeyCallback(window, keyCallback = new GLFWKeyCallback() {
            @Override
            public void invoke(long window, int key, int scancode, int action, int mods) {
                if ( key == GLFW_KEY_ESCAPE && action == GLFW_RELEASE )
                    glfwSetWindowShouldClose(window, GLFW_TRUE);
            }
        });

        GLFWVidMode vidmode = glfwGetVideoMode(glfwGetPrimaryMonitor());

        glfwSetWindowPos(
            window,
            (vidmode.width() - WIDTH) / 2,
            (vidmode.height() - HEIGHT) / 2
        );

        glfwMakeContextCurrent(window);
        glfwSwapInterval(1);

        glfwShowWindow(window);
    }

    private void loop() {
        GL.createCapabilities();

        glClearColor(1.0f, 1.0f, 1.0f, 0.0f);

        while ( glfwWindowShouldClose(window) == GLFW_FALSE ) {
            glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

            draw();

            glfwSwapBuffers(window);

            glfwPollEvents();
        }
    }

    private static void draw(){

        int vertices = 4;
        int colorSize = 3;
        int vertexSize = 3;

        FloatBuffer cBuffer = BufferUtils.createFloatBuffer(vertices * colorSize);
        cBuffer.put(0).put(0).put(0);
        cBuffer.put(0).put(0).put(0);
        cBuffer.put(0).put(0).put(0);
        cBuffer.put(0).put(0).put(0);
        cBuffer.flip();

        FloatBuffer vBuffer = BufferUtils.createFloatBuffer(vertices * vertexSize);
        vBuffer.put(0.4056f).put(0.5792f).put(0.0f);
        vBuffer.put(-0.5792f).put(0.4056f).put(0.0f);
        vBuffer.put(-0.4056f).put(-0.5792f).put(0.0f);
        vBuffer.put(0.5792f).put(-0.4056f).put(0.0f);
        vBuffer.flip();



        IntBuffer ib = BufferUtils.createIntBuffer(2);

        glGenBuffers(ib);

        int vHandle = ib.get(0);
        int cHandle = ib.get(1);

        glEnableClientState(GL_VERTEX_ARRAY);
        glEnableClientState(GL_COLOR_ARRAY);

        glBindBuffer(GL_ARRAY_BUFFER, vHandle);
        glBufferData(GL_ARRAY_BUFFER, vBuffer, GL_STATIC_DRAW);
        glVertexPointer(vertexSize, GL_FLOAT, vertexSize*4, 0);

        glBindBuffer(GL_ARRAY_BUFFER, cHandle);
        glBufferData(GL_ARRAY_BUFFER, cBuffer, GL_STATIC_DRAW);
        glColorPointer(colorSize, GL_FLOAT, colorSize*4, 0);

        glDrawArrays(GL_POLYGON, 0, vertices);

        glBindBuffer(GL_ARRAY_BUFFER, 0);

        glDisableClientState(GL_COLOR_ARRAY);
        glDisableClientState(GL_VERTEX_ARRAY);

        ib.put(0, vHandle);
        ib.put(1, cHandle);
        glDeleteBuffers(ib);

    }

    public static void main(String[] args){

        new LWJGLTest().run();

    }

}

Answer 1

You can enable multisampling (MSAA) in GLFW which should give you the effect you want. Look up using GL_SAMPLES on it.

eg

glfwWindowHint(GLFW_STENCIL_BITS, 4);
glfwWindowHint(GLFW_SAMPLES, 4);

before you create the window.