CODEWITHSUNDEEP
javaopengllwjgl
themorfeus
themorfeus

Reputation: 287

Quads appear in front of others while they're not

I am trying to write a simple Doom style game, and for that matter i've decided to write a block-type engine (much simmilar to Minecraft), however i have ran into a problem: The blocks render really oddly, with parts of blocks passing through like nothing is there.

This is what happens when you look at quad from left:left However, when you look at it from right, everything looks perfectly fine: right

Let's get to the code, shall we? This is how i initialise OpenGL:

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();

    gluPerspective(fov, (float) Display.getWidth() / (float) Display.getHeight(), 0, -2);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    glEnable(GL_TEXTURE_2D);
    glEnable(GL_BLEND);
    glEnable(GL_CULL_FACE);
    glCullFace(GL_BACK);

I render block's faces using display lists. I tried using VBO's, but changed to display lists, as i thought they caused the problem. Every display list looks generally the same:

        glNewList(listTop, GL_COMPILE);
        glBegin(GL_QUADS);
        tex.bind();
            glTexCoord2f(0, 0);
        glVertex3f(x+0.0f, y+1.0f, z-1.0f); 
            glTexCoord2f(0, 1);
        glVertex3f(x+0.0f, y+1.0f, z+0.0f); 
            glTexCoord2f(1, 1);
        glVertex3f(x+1.0f, y+1.0f, z+0.0f); 
            glTexCoord2f(1, 0);
        glVertex3f(x+1.0f, y+1.0f, z-1.0f); 
        glEnd();
    glEndList();

And then there's rendering:

glClearColor(0, .5f, 0, 1);
    glClear(GL_COLOR_BUFFER_BIT);

            glPushMatrix();

          if(rTo)glCallList(listTop);
          if(rBt)glCallList(listBot);
          if(rFr)glCallList(listFront);
          if(rBk)glCallList(listBack);
          if(rLe)glCallList(listLeft);
          if(rRi)glCallList(listRight);

            glPopMatrix();

    glLoadIdentity();
    //Display.update() etc here

So, what might be causing this bug? Anyone had simillar problems?

Upvotes: 1

Views: 66

Answers (2)

themorfeus
themorfeus

Reputation: 287

Ok, so it turns out i didn't enable GL_DEPTH_TEST. While that was the problem, it was not the only one. The biggest problem was in gluPerspective method, the zNear was set to 0, i learnt that it needs to be above 0. So,changing this line:

gluPerspective(fov, (float) Display.getWidth() / (float) Display.getHeight(), 0, -2);

To this:

gluPerspective(fov, (float) Display.getWidth() / (float) Display.getHeight(), 0.1f, -2);

AND enabling GL_DEPTH_TEST fixed everything :)

Upvotes: 1

BlastDV
BlastDV

Reputation: 110

I don't see that you are enabling the DEPTH TEST,

glEnable(GL_DEPTH_TEST);

Also, you have to clear the depth buffer on every frame.

Try to do that before rendering your scene, since it looks that objects are being incorrectly overlayed. Also, I think that you shouldn't set your near value in the projection matrix to Zero, since it may cause you some troubles later.

Upvotes: 5

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