Some LWJGL 3d help?

[PeterNicholson]

Hello All!
I am currently trying to learn opengl 3d rendering. I am using LWJGL as my engine. But I have got this problem. I follow tutorials from all over the internet, but when I run it in Eclipse, I just get a black screen:



This is the source code:

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import org.lwjgl.LWJGLException; import org.lwjgl.opengl.Display; import org.lwjgl.opengl.DisplayMode; import static org.lwjgl.opengl.GL11.*; import org.lwjgl.input.Keyboard; import org.lwjgl.input.Mouse; import static org.lwjgl.util.glu.GLU.*; public class Main {        public static void main(String args[]) {       Main game = new Main();       game.run();    }        private void run() {             try {          Display.setDisplayMode(new DisplayMode(500, 400));          Display.setTitle("Hello World!");          Display.create();       } catch (LWJGLException ex) {          ex.printStackTrace();          System.exit(0);       }             glMatrixMode(GL_PROJECTION);       glLoadIdentity();       gluPerspective(45.0f,((float)500)/((float)400),0.1f,100.0f);       glEnable(GL_DEPTH_TEST);       glMatrixMode(GL_MODELVIEW);             while (!Display.isCloseRequested()) {                    render();                    Display.update();          Display.sync(60);                    if (Keyboard.isKeyDown(Keyboard.KEY_ESCAPE)) {             System.exit(0);          }       }          }        public static void render() {             glPushMatrix();             glColor3f(0.0f, 0.5f, 0.0f);             glBegin(GL_QUADS);          glVertex3f(0.0f, 1.0f, 0.0f);          glVertex3f(0.0f, 1.0f, -1.0f);          glVertex3f(1.0f, 1.0f, -1.0f);          glVertex3f(1.0f, 1.0f, 0.0f);       glEnd();             glPopMatrix();          }     }

Please Help! If you have any more questions, then ask!

[Giovanni]

Some things:

First of all, you forgot glClear. You have to call it in order for the quad to be visible. So your code should look like this:

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while (!Display.isCloseRequested()) {          glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);                   render();                    Display.update();          Display.sync(60);                    if (Keyboard.isKeyDown(Keyboard.KEY_ESCAPE)) {             System.exit(0);          }       }

The second thing; The coordinates of your quad were pretty weird, especially the z-coords:

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glVertex3f(0.0f, 1.0f, 0.0f); glVertex3f(0.0f, 1.0f, -1.0f); glVertex3f(1.0f, 1.0f, -1.0f); glVertex3f(1.0f, 1.0f, 0.0f);

I think you missunderstood something here. The function's parameters are like following:
glVertex3f(x, y, z);

The z-axis is in your case the depth of the whole scene. The way you specified the z-coords would mean that your quad had some weird rotation. Also, some coordinates have the same x and y coordiantes which doesn't really make sense in this case. I changed the coordinates a little bit so that the quad gets displayed:

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glBegin(GL_QUADS);          glVertex3f(-1.0f, 1.0f, -5.0f);          glVertex3f(1.0f, 1.0f, -5.0f);          glVertex3f(1.0f, -1.0f, -5.0f);          glVertex3f(-1.0f, -1.0f, -5.0f); glEnd();

The third thing; You don't seem to be really familiar with the OpenGL coordinate system or other basic stuff. You better stick to 2D rendering for a little bit longer to gain more knowledge.


The fourth thing; Immediate mode is wicked (yes, wicked)! It appeared in the first OpenGL version (if I'm right) which was released around 1992. I think it should be quite obvious that it is by now totally deprecated. In newer OpenGL versions these functions don't even exist anymore. You should better skip Immediate-Mode rendering and start with more modern techniques like using VAOs & VBOs or whatever.



Edit: This post should help you: http://www.java-gaming.org/topics/hello/24411/msg/205121/view.html#msg205121

[PeterNicholson]

Hi!
Thanks for your`e help!  I think I will try a bit more of 2d! Thanks for your`e help