CODEWITHSUNDEEP
javaopengl
thrash
thrash

Reputation: 187

Java openGL - drawing a 3D object

Im looking to draw a 3D object in openGL but whats the best way to approach this? I was thinking of drawing the side profile of it in 2D and maybe then fleshing it out to become 3D but is that possible? I think it would be easier to do it that way then just go straight into 3D but if you cant then id just be wasting my time.

I also cant figure out how to add the sky and maybe even the sea with a reflection, is this easily done?

   gl.glClear(GL.GL_COLOR_BUFFER_BIT);
   gl.glColor3f(1.0f, 1.0f, 1.0f);

   gl.glPushMatrix();
   gl.glTranslatef(-1.0f, 0.0f, 0.0f);
   gl.glRotatef((float) shoulder, 0.0f, 0.0f, 1.0f);
   gl.glTranslatef(1.0f, 0.0f, 0.0f);
   // gl.glPushMatrix();
   gl.glScalef(2.0f, 0.4f, 1.0f);
   glut.glutWireCube(1.0f);
   // gl.glPopMatrix();

   gl.glTranslatef(1.0f, 0.0f, 0.0f);
   gl.glRotatef((float) elbow, 0.0f, 0.0f, 1.0f);
   gl.glTranslatef(1.0f, 0.0f, 0.0f);
   // gl.glPushMatrix();
   gl.glScalef(2.0f, 0.4f, 1.0f);
   glut.glutWireCube(1.0f);
   // gl.glPopMatrix();

   gl.glTranslatef(1.0f, 1.0f, 1.0f);
   gl.glRotatef((float) hand, 0.0f, 0.0f, 1.0f);
   gl.glTranslatef(1.0f, 0.0f, 0.0f);
   // gl.glPushMatrix();
   gl.glScalef(2.0f, 0.4f, 1.0f);
   glut.glutWireCube(1.0f);
   // gl.glPopMatrix();

Ive just been trying random numbers to try and get it to work but not such luck so far!

Upvotes: 0

Views: 1912

Answers (1)

user1650305
user1650305

Reputation:

Ok first, reflections can be hard depending on how you want to do them. You will definitely need to learn more OpenGL before attempting something like that. Second, 3D objects require some more matrix stuff, this is an example from my init method in my 3D game:

private void initGl() {
    glViewport(0, 0, Display.getWidth(), Display.getHeight());
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    GLU.gluPerspective(45.0f, Display.getWidth() / Display.getHeight(), 1.0f, 100.0f);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
    glClearDepth(1.0f);
    glDepthFunc(GL_LEQUAL);
    glEnable(GL_DEPTH_TEST);
    glShadeModel(GL_SMOOTH);
    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
    glEnable(GL_FOG);
    glFogi(GL_FOG_MODE, GL_EXP2);
    glFogf(GL_FOG_DENSITY, density);
    glHint(GL_FOG_DENSITY, GL_FASTEST);
    glEnable(GL_CULL_FACE);
    glCullFace(GL_BACK);
}

You will also need to clear the buffer like this before drawing:

        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

You are almost correct when you say just flesh out a 2D object. If we were still using immediate mode (glBegin()/glEnd()), your approach would be correct. However, immediate mode is deprecated now and we usually use VBOs. I would suggest going on YouTube and searching for theCodingUniverse if you are using LWJGL, he has a video on VBOs and advanced rendering, its how I learned them!

Good luck in the world of 3D, its not easy at all, but its (in my opinion), much more satisfying than 2D when you get something working.

Also, consider investing in the RedBook, its all about LWJGL.

Upvotes: 1

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