Question

Im trying to make a basic shape ( Hexigon ) to start and learn some basics about OpenGL on the Android platform and i have a little problem.

I have successfully made a pointy Hexagon, but when i convert it into a flat Hexygon it doesnt render correctly. Here is some code, for you guys to figure out the problem ( probably a easy fix.. )

vertices / indices

//flat hexagon
private float verticesFlat[] = {     
    0.0f,   0.0f, 0.0f,    //center
    -0.5f,   1.0f, 0.0f,    // left top
    0.5f,   1.0f, 0.0f,    // right top
    1.0f,   0.0f, 0.0f,    // right
    0.5f,   1.0f, 0.0f,    // right bottom
    -0.5f,  -1.0f, 0.0f,    // left bottom
    -1.0f,   0.0f, 0.0f,     // left
};

private short[] indices = { 0, 1, 2, 3, 4, 5, 6, 1 };

standard vertex / index Buffers..

// a float is 4 bytes, therefore we multiply the number if
// vertices with 4.
ByteBuffer vbb = ByteBuffer.allocateDirect(verticesFlat.length * 4);
vbb.order(ByteOrder.nativeOrder());
vertexBuffer = vbb.asFloatBuffer();
vertexBuffer.put(verticesFlat);
vertexBuffer.position(0);

// short is 2 bytes, therefore we multiply the number if
// vertices with 2.
ByteBuffer ibb = ByteBuffer.allocateDirect(indices.length * 2);
ibb.order(ByteOrder.nativeOrder());
indexBuffer = ibb.asShortBuffer();
indexBuffer.put(indices);
indexBuffer.position(0);

The onDraw(GL10 gl):

gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);

gl.glMatrixMode(GL10.GL_MODELVIEW);
gl.glLoadIdentity();

GLU.gluLookAt(gl, 0, 0, -5, 0f, 0f, 0f, 0f, 1.0f, 0.0f);    

gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);

gl.glVertexPointer(3, GL10.GL_FLOAT, 0, vertexBuffer);
gl.glDrawElements(GL10.GL_TRIANGLE_FAN, indices.length, GL10.GL_UNSIGNED_SHORT, indexBuffer);

gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);

The result im getting is illustrated in the image below:

Answer 1

Should be

private float verticesFlat[] = {     
    0.0f,   0.0f, 0.0f,    //center
    -0.5f,   1.0f, 0.0f,    // left top
    0.5f,   1.0f, 0.0f,    // right top
    1.0f,   0.0f, 0.0f,    // right
    0.5f,   -1.0f, 0.0f,    // right bottom (notice sign)
    -0.5f,  -1.0f, 0.0f,    // left bottom
    -1.0f,   0.0f, 0.0f,     // left
};