Poor shading problem in Android OpenGL ES

I set up diffuse lighting:

private float[] lightAmbient = { 0.5f, 0.5f, 0.5f, 1.0f };
private float[] lightDiffuse = { 1.0f, 1.0f, 1.0f, 1.0f };
private float[] lightPosition = { 0.0f, 0.0f, 2.0f, 1.0f };

gl.glLightfv(GL10.GL_LIGHT0, GL10.GL_AMBIENT, lightAmbientBuffer);
gl.glLightfv(GL10.GL_LIGHT0, GL10.GL_DIFFUSE, lightDiffuseBuffer);

gl.glLightfv(GL10.GL_LIGHT0, GL10.GL_POSITION, lightPositionBuffer);
gl.glEnable(GL10.GL_LIGHT0);

gl.gl开发者_运维技巧ShadeModel(GL10.GL_SMOOTH);

But I get triangulated shading or flat color on the cube located at origin ( center) and rotated 45 deg around x and y. So the cube is directly in front of the light. Any reasons why I am getting such poor results? Attached is the cube image.

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OpenGL ES calculates colors at the vertices of each triangle. The color is then interpolated across the triangle, Ideally the vertices should calculate the same colors between the two triangles but a variety of situations could cause it not to.

It appears are though your cube edges are modeled with two triangles. You could decompose the cube side into more triangles, but that adds more memory storage and could slow down drawing.

You could also move to OpenGL ES 2.0 and write a shader, which can properly interpolate the colors across the surface, but that will require rewriting the entire pipeline. OGL ES doesn't let you mix old style and shader based implementations.