I attempted to follow the LWJGL 3.2+ Tutorial on drawElements and get my LWJGL application to draw a quad. My code runs successfully but doesn't draw anything (apart from the basic window), no matter where I run my loopCycle method that should draw the quad. I assume it has to do with the change from Display (Tutorial) to GLFW (my code)? I saw some posts talking about Projection, View and Model matrices that I do not use (afaik), is that the issue why it doesn't display?
package org.tempest.game;
import org.lwjgl.*;
import org.lwjgl.glfw.*;
import org.lwjgl.opengl.*;
import org.lwjgl.system.*;
import java.nio.*;
import static org.lwjgl.glfw.Callbacks.*;
import static org.lwjgl.glfw.GLFW.*;
import static org.lwjgl.opengl.GL11.*;
import static org.lwjgl.system.MemoryStack.*;
import static org.lwjgl.system.MemoryUtil.*;
public class Graphics {
// The window handle
private long window;
// Window setup
private final String WINDOW_TITLE = "Test";
// 1920x1080, 1600x900 and 1200x675 are all 16:9 ratios
private final int WIDTH = 320;
private final int HEIGHT = 240;
// Quad variables
private int vaoId = 0;
private int vboId = 0;
private int vboiId = 0;
private int indicesCount = 0;
public static void main(String[] args) {
new Graphics().run();
}
public void run() {
System.out.println("Hello LWJGL " + Version.getVersion() + "!");
init();
setupQuad();
loop();
destroyOpenGL();
// Free the window callbacks and destroy the window
glfwFreeCallbacks(window);
glfwDestroyWindow(window);
// Terminate GLFW and free the error callback
glfwTerminate();
glfwSetErrorCallback(null).free();
}
private void init() {
// Setup an error callback. The default implementation
// will print the error message in System.err.
GLFWErrorCallback.createPrint(System.err).set();
// Initialize GLFW. Most GLFW functions will not work before doing this.
if ( !glfwInit() )
throw new IllegalStateException("Unable to initialize GLFW");
// Configure GLFW
glfwDefaultWindowHints(); // optional, the current window hints are already the default
glfwWindowHint(GLFW_VISIBLE, GLFW_FALSE);
glfwWindowHint(GLFW_RESIZABLE, GLFW_TRUE);
// Create the window
window = glfwCreateWindow(WIDTH, HEIGHT, WINDOW_TITLE, NULL, NULL);
if ( window == NULL )
throw new RuntimeException("Failed to create the GLFW window");
// Setup a key callback. It will be called every time a key is pressed, repeated or released.
glfwSetKeyCallback(window, (window, key, scancode, action, mods) -> {
if ( key == GLFW_KEY_ESCAPE && action == GLFW_RELEASE )
glfwSetWindowShouldClose(window, true); // We will detect this in the rendering loop
});
// Get the thread stack and push a new frame
try ( MemoryStack stack = stackPush() ) {
IntBuffer pWidth = stack.mallocInt(1); // int*
IntBuffer pHeight = stack.mallocInt(1); // int*
// Get the window size passed to glfwCreateWindow
glfwGetWindowSize(window, pWidth, pHeight);
// Get the resolution of the primary monitor
GLFWVidMode vidmode = glfwGetVideoMode(glfwGetPrimaryMonitor());
// Center the window
glfwSetWindowPos(
window,
(vidmode.width() - pWidth.get(0)) / 2,
(vidmode.height() - pHeight.get(0)) / 2
);
} // the stack frame is popped automatically
// Make the OpenGL context current
glfwMakeContextCurrent(window);
// Enable v-sync with 1
glfwSwapInterval(0);
// Make the window visible
glfwShowWindow(window);
}
private void loop() {
// Initialize variables for fps calculation
long time_start = System.nanoTime();
int frames = 0;
final double check_fps_time = 1d;
// Set the clear color
glClearColor(0.2f, 0.2f, 0.2f, 0.0f);
// TODO Where to initialize this?
//GL11.glViewport(0, 0, WIDTH, HEIGHT);
// Run the rendering loop until the user has attempted to close
// the window or has pressed the ESCAPE key.
while ( !glfwWindowShouldClose(window) ) {
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // clear the framebuffer
glfwSwapBuffers(window); // swap the color buffers
// Count, calculate and display fps
frames++;
long time_now = System.nanoTime();
if ((double)(time_now - time_start)/1000000000 > check_fps_time) {
int fps_prediction = (int)(frames/check_fps_time);
System.out.println("FPS: " + fps_prediction);
frames = 0;
time_start = time_now;
}
// Poll for window events. The key callback above will only be
// invoked during this call.
glfwPollEvents();
loopCycle();
}
}
public void setupQuad() {
GL.createCapabilities();
// Vertices, the order is not important.
float[] vertices = {
-0.5f, 0.5f, 0f, // Left top ID: 0
-0.5f, -0.5f, 0f, // Left bottom ID: 1
0.5f, -0.5f, 0f, // Right bottom ID: 2
0.5f, 0.5f, 0f // Right left ID: 3
};
// Sending data to OpenGL requires the usage of (flipped) byte buffers
FloatBuffer verticesBuffer = BufferUtils.createFloatBuffer(vertices.length);
verticesBuffer.put(vertices);
verticesBuffer.flip();
// OpenGL expects to draw vertices in counter clockwise order by default
byte[] indices = {
// Left bottom triangle
0, 1, 2,
// Right top triangle
2, 3, 0
};
indicesCount = indices.length;
ByteBuffer indicesBuffer = BufferUtils.createByteBuffer(indicesCount);
indicesBuffer.put(indices);
indicesBuffer.flip();
// Create a new Vertex Array Object in memory and select it (bind)
// A VAO can have up to 16 attributes (VBOs) assigned to it by default
vaoId = GL30.glGenVertexArrays();
GL30.glBindVertexArray(vaoId);
// Create a new Vertex Buffer Object in memory and select it (bind)
// A VBO is a collection of Vectors which in this case resemble the location of each vertex.
vboId = GL15.glGenBuffers();
GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, vboId);
GL15.glBufferData(GL15.GL_ARRAY_BUFFER, verticesBuffer, GL15.GL_STATIC_DRAW);
// Put the VBO in the attributes list at index 0
GL20.glVertexAttribPointer(0, 3, GL11.GL_FLOAT, false, 0, 0);
// Deselect (bind to 0) the VBO
GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, 0);
// Deselect (bind to 0) the VAO
GL30.glBindVertexArray(0);
// Create a new VBO for the indices and select it (bind)
vboiId = GL15.glGenBuffers();
GL15.glBindBuffer(GL15.GL_ELEMENT_ARRAY_BUFFER, vboiId);
GL15.glBufferData(GL15.GL_ELEMENT_ARRAY_BUFFER, indicesBuffer, GL15.GL_STATIC_DRAW);
// Deselect (bind to 0) the VBO
GL15.glBindBuffer(GL15.GL_ELEMENT_ARRAY_BUFFER, 0);
}
public void loopCycle() {
GL11.glClear(GL11.GL_COLOR_BUFFER_BIT);
// Bind to the VAO that has all the information about the vertices
GL30.glBindVertexArray(vaoId);
GL20.glEnableVertexAttribArray(0);
// Bind to the index VBO that has all the information about the order of the vertices
GL15.glBindBuffer(GL15.GL_ELEMENT_ARRAY_BUFFER, vboiId);
// Draw the vertices
GL11.glDrawElements(GL11.GL_TRIANGLES, indicesCount, GL11.GL_UNSIGNED_BYTE, 0);
// Put everything back to default (deselect)
GL15.glBindBuffer(GL15.GL_ELEMENT_ARRAY_BUFFER, 0);
GL20.glDisableVertexAttribArray(0);
GL30.glBindVertexArray(0);
}
public void destroyOpenGL() {
// Disable the VBO index from the VAO attributes list
GL20.glDisableVertexAttribArray(0);
// Delete the vertex VBO
GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, 0);
GL15.glDeleteBuffers(vboId);
// Delete the index VBO
GL15.glBindBuffer(GL15.GL_ELEMENT_ARRAY_BUFFER, 0);
GL15.glDeleteBuffers(vboiId);
// Delete the VAO
GL30.glBindVertexArray(0);
GL30.glDeleteVertexArrays(vaoId);
}
public int getWIDTH() {
return WIDTH;
}
public int getHEIGHT() {
return HEIGHT;
}
}
I am a beginner and probably there are a number of things I need to look into to make this work. I would love to hear some guidance on what to look into to get my application to do something so I can take things from there. Thank you so much! :)
There is at least one issue with this code- it calls clear/draw/swap in the wrong order. Basically with OpenGL, the main loop should call clear() first, draw some things, and then call swapBuffers() to display the buffer contents.
The example instead: calls clear (ok, clear the buffer), swaps the buffers (here a blank window is shown, since the buffer is cleared), and then draws a bunch of stuff to the buffer. But the buffer contents is never displayed (since in the next cycle, the first operation is clear() again).
Below the slightly modified code; it draws a white rectangle - I am not totally sure about the usage of glBindBuffer (I used drawLine and drawTriangle in the past), but it's a start.
package sample;
import org.lwjgl.*;
import org.lwjgl.glfw.*;
import org.lwjgl.opengl.*;
import org.lwjgl.system.*;
import java.nio.*;
import static org.lwjgl.glfw.Callbacks.*;
import static org.lwjgl.glfw.GLFW.*;
import static org.lwjgl.opengl.GL11.*;
import static org.lwjgl.system.MemoryStack.*;
import static org.lwjgl.system.MemoryUtil.*;
public class DrawExample {
// The window handle
private long window;
// Window setup
private final String WINDOW_TITLE = "Test";
// 1920x1080, 1600x900 and 1200x675 are all 16:9 ratios
private final int WIDTH = 320;
private final int HEIGHT = 240;
// Quad variables
private int vaoId = 0;
private int vboId = 0;
private int vboiId = 0;
private int indicesCount = 0;
public static void main(String[] args) {
new DrawExample().run();
}
public void run() {
System.out.println("Hello LWJGL " + Version.getVersion() + "!");
init();
setupQuad();
loop();
destroyOpenGL();
// Free the window callbacks and destroy the window
glfwFreeCallbacks(window);
glfwDestroyWindow(window);
// Terminate GLFW and free the error callback
glfwTerminate();
glfwSetErrorCallback(null).free();
}
private void init() {
// Setup an error callback. The default implementation
// will print the error message in System.err.
GLFWErrorCallback.createPrint(System.err).set();
// Initialize GLFW. Most GLFW functions will not work before doing this.
if (!glfwInit())
throw new IllegalStateException("Unable to initialize GLFW");
// Configure GLFW
glfwDefaultWindowHints(); // optional, the current window hints are already the default
glfwWindowHint(GLFW_VISIBLE, GLFW_FALSE);
glfwWindowHint(GLFW_RESIZABLE, GLFW_TRUE);
// Create the window
window = glfwCreateWindow(WIDTH, HEIGHT, WINDOW_TITLE, NULL, NULL);
if (window == NULL)
throw new RuntimeException("Failed to create the GLFW window");
// Setup a key callback. It will be called every time a key is pressed, repeated or released.
glfwSetKeyCallback(window, (window, key, scancode, action, mods) -> {
if (key == GLFW_KEY_ESCAPE && action == GLFW_RELEASE)
glfwSetWindowShouldClose(window, true); // We will detect this in the rendering loop
});
// Get the resolution of the primary monitor
GLFWVidMode vidmode = glfwGetVideoMode(glfwGetPrimaryMonitor());
// Get the thread stack and push a new frame
try (MemoryStack stack = stackPush()) {
IntBuffer pWidth = stack.mallocInt(1); // int*
IntBuffer pHeight = stack.mallocInt(1); // int*
// Get the window size passed to glfwCreateWindow
glfwGetWindowSize(window, pWidth, pHeight);
// Center the window
glfwSetWindowPos(window, (vidmode.width() - pWidth.get(0)) / 2,
(vidmode.height() - pHeight.get(0)) / 2);
} // the stack frame is popped automatically
// Make the OpenGL context current
glfwMakeContextCurrent(window);
// Enable v-sync with 1
glfwSwapInterval(1);
// Make the window visible
glfwShowWindow(window);
}
private void loop() {
// Initialize variables for fps calculation
long time_start = System.nanoTime();
int frames = 0;
final double check_fps_time = 1d;
// Set the clear color
glClearColor(0.2f, 0.2f, 0.2f, 0.0f);
// TODO Where to initialize this?
// GL11.glViewport(0, 0, WIDTH, HEIGHT);
// Run the rendering loop until the user has attempted to close
// the window or has pressed the ESCAPE key.
while (!glfwWindowShouldClose(window)) {
// Count, calculate and display fps
frames++;
long time_now = System.nanoTime();
if ((double) (time_now - time_start) / 1000000000 > check_fps_time) {
int fps_prediction = (int) (frames / check_fps_time);
System.out.println("FPS: " + fps_prediction);
frames = 0;
time_start = time_now;
}
// Poll for window events. The key callback above will only be
// invoked during this call.
glfwPollEvents();
loopCycle();
glfwSwapBuffers(window); // swap the color buffers
}
}
public void setupQuad() {
GL.createCapabilities();
// Vertices, the order is not important.
float[] vertices = {-0.5f, 0.5f, 0f, // Left top ID: 0
-0.5f, -0.5f, 0f, // Left bottom ID: 1
0.5f, -0.5f, 0f, // Right bottom ID: 2
0.5f, 0.5f, 0f // Right left ID: 3
};
// Sending data to OpenGL requires the usage of (flipped) byte buffers
FloatBuffer verticesBuffer = BufferUtils.createFloatBuffer(vertices.length);
verticesBuffer.put(vertices);
verticesBuffer.flip();
// OpenGL expects to draw vertices in counter clockwise order by default
byte[] indices = {
// Left bottom triangle
0, 1, 2,
// Right top triangle
2, 3, 0};
indicesCount = indices.length;
ByteBuffer indicesBuffer = BufferUtils.createByteBuffer(indicesCount);
indicesBuffer.put(indices);
indicesBuffer.flip();
// Create a new Vertex Array Object in memory and select it (bind)
// A VAO can have up to 16 attributes (VBOs) assigned to it by default
vaoId = GL30.glGenVertexArrays();
GL30.glBindVertexArray(vaoId);
// Create a new Vertex Buffer Object in memory and select it (bind)
// A VBO is a collection of Vectors which in this case resemble the location of each vertex.
vboId = GL15.glGenBuffers();
GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, vboId);
GL15.glBufferData(GL15.GL_ARRAY_BUFFER, verticesBuffer, GL15.GL_STATIC_DRAW);
// Put the VBO in the attributes list at index 0
GL20.glVertexAttribPointer(0, 3, GL11.GL_FLOAT, false, 0, 0);
// Deselect (bind to 0) the VBO
GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, 0);
// Deselect (bind to 0) the VAO
GL30.glBindVertexArray(0);
// Create a new VBO for the indices and select it (bind)
vboiId = GL15.glGenBuffers();
GL15.glBindBuffer(GL15.GL_ELEMENT_ARRAY_BUFFER, vboiId);
GL15.glBufferData(GL15.GL_ELEMENT_ARRAY_BUFFER, indicesBuffer, GL15.GL_STATIC_DRAW);
// Deselect (bind to 0) the VBO
GL15.glBindBuffer(GL15.GL_ELEMENT_ARRAY_BUFFER, 0);
}
public void loopCycle() {
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// Bind to the VAO that has all the information about the vertices
GL30.glBindVertexArray(vaoId);
GL20.glEnableVertexAttribArray(0);
// Bind to the index VBO that has all the information about the order of the vertices
GL15.glBindBuffer(GL15.GL_ELEMENT_ARRAY_BUFFER, vboiId);
// Draw the vertices
GL11.glDrawElements(GL11.GL_TRIANGLES, indicesCount, GL11.GL_UNSIGNED_BYTE, 0);
// Put everything back to default (deselect)
GL15.glBindBuffer(GL15.GL_ELEMENT_ARRAY_BUFFER, 0);
GL20.glDisableVertexAttribArray(0);
GL30.glBindVertexArray(0);
}
public void destroyOpenGL() {
// Disable the VBO index from the VAO attributes list
GL20.glDisableVertexAttribArray(0);
// Delete the vertex VBO
GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, 0);
GL15.glDeleteBuffers(vboId);
// Delete the index VBO
GL15.glBindBuffer(GL15.GL_ELEMENT_ARRAY_BUFFER, 0);
GL15.glDeleteBuffers(vboiId);
// Delete the VAO
GL30.glBindVertexArray(0);
GL30.glDeleteVertexArrays(vaoId);
}
public int getWIDTH() {
return WIDTH;
}
public int getHEIGHT() {
return HEIGHT;
}
}