Lighting with VBO

Question

INTRO

I'm using a Java JOGL wrapper called processing.org and I have coded some environment on it and I'm quite proud of it even if it has some library stuff that I didn't know anything about it (==LIGHTS).

Now, for some geometry, I've decided to use a VBO. I had to pass in the hard way and recode all lights. But I can't achieve the same result.

With that environment if i use the standard lights i get this result:

This environment wrap the opengl functions and i don't manage to understand the pure OPENGL calls.

i know that the code for standard light in processing.org enviroment is:

public void lights() {
    enableLighting();

    // need to make sure colorMode is RGB 255 here
    int colorModeSaved = colorMode;
    colorMode = RGB;

    lightFalloff(1, 0, 0);
    lightSpecular(0, 0, 0);

    ambientLight(colorModeX * 0.5f, colorModeY * 0.5f, colorModeZ * 0.5f);
    directionalLight(colorModeX * 0.5f, colorModeY * 0.5f, colorModeZ * 0.5f, 0, 0, -1);

    colorMode = colorModeSaved;
}

PROBLEM

I want to replicate this light system with pure openGL calls.

Now, i have done some trial with no succes.

ambient and spot lights:

adding smooth and flat:

QUESTION

Now, i'd like for someone to help me in analysing the first picture and help me in understanding what kind (light or material or whatever) of OPENGL calls i can use to achieve a similar result.

CODE

this is my code so far:

gl.glEnable(GL.GL_LIGHTING);
gl.glEnable(GL.GL_LIGHT0);
gl.glEnable(GL.GL_COLOR_MATERIAL);
gl.glShadeModel(GL.GL_SMOOTH);
gl.glShadeModel(GL.GL_FLAT);

Vec3D l = new Vec3D(0,0,-10);
gl.glColor3f(0.8f,0f,0f);
gl.glLightfv(GL.GL_LIGHT0, GL.GL_POSITION, new float[] { l.x, l.y, l.z, 0 }, 0);
gl.glLightfv(GL.GL_LIGHT0, GL.GL_SPOT_DIRECTION, new float[] { 1, 1, 1 }, 0);
//gl.glLightfv(GL.GL_LIGHT0, GL.GL_SPECULAR, new float[] { 1, 1, 1}, 0); // if i comment this line nothing change, why?

gl.glMaterialfv(GL.GL_FRONT_AND_BACK, GL.GL_AMBIENT,        new float[]{1f,0f,0f}, 0);
gl.glMaterialfv(GL.GL_FRONT_AND_BACK, GL.GL_SPOT_DIRECTION, new float[]{1f,0f,0f}, 0);
//gl.glMaterialfv(GL.GL_FRONT_AND_BACK, GL.GL_SPECULAR, new float[]{1f, 1f, 1f, 1.0f}, 0);  // if i comment this line nothing change, why?

Answer 1

Check your normals!

In the first image, each face has three vertices with the same normal as the face. These vertices are not shared between faces.

In your data, each vertex is shared by multiple faces. As such, it has a normal computed from the average of the normals of all the faces it's connected to.

You need to re-export your data, to get the normals you want. Either that, or re-compute normals per face. Just remember that you can't share vertices between faces.

Answer 2

It seems to me that you're either passing smooth normals or have smooth shading enabled in the 2nd picture compared to the first one, but I can't really tell with just what you have posted.