CC3MeshNode is not affected by light in cocos3d

Question

I have drawn a complex 3d shape using CC3MeshNode in cocos3d, but this shape is not affected (shadow and bright places depending on positioning) by the light source (lamp) that i set in the world, where if i use one of the populateAs methods to draw something like a sphere it will get affected by the light source. What should i do while manually drawing a CC3MeshNode so that it will get affected by light.

Here is a sample code of drawing a rectangle manually in cocos3d

    CC3MeshNode *pMeshNode = [[CC3MeshNode alloc] init];
    [pMeshNode setIsTouchEnabled:YES];

    CC3Mesh* theArrayMesh = [pMeshNode prepareParametricMesh];
    // Prepare the vertex content and allocate space for vertices and indices.
    [theArrayMesh ensureVertexContent];
    theArrayMesh.allocatedVertexCapacity = totalVertexCount;
    theArrayMesh.allocatedVertexIndexCapacity = (triangleCount * 3);
    GLushort* indices = theArrayMesh.vertexIndices.vertices;

    /*
     *  1-------0
     *  |      /|   -z
     *  |     / |    ⥣
     *  |    /  |     =>+x
     *  |   /   |
     *  |  /    |
     *  | /     |
     *  |/      |
     *  2-------3
     */
    {
        [theArrayMesh setVertexLocation: cc3v(3, -3,0) at: 3];
        [theArrayMesh setVertexLocation: cc3v(-3, -3,0 ) at: 2];
        [theArrayMesh setVertexLocation: cc3v(-3, 3, 0) at: 1];
        [theArrayMesh setVertexLocation: cc3v(3, 3, 0) at: 0];

    }
    GLubyte indxIndx = 0;
    GLubyte vtxIndx = 0;
    for (int side = 0; side < 1; side++) {
        // First trangle of side - CCW from bottom left
        indices[indxIndx++] = vtxIndx++;        // vertex 0
        indices[indxIndx++] = vtxIndx++;        // vertex 1
        indices[indxIndx++] = vtxIndx;          // vertex 2

        // Second triangle of side - CCW from bottom left
        indices[indxIndx++] = vtxIndx++;        // vertex 2
        indices[indxIndx++] = vtxIndx++;        // vertex 3
        indices[indxIndx++] = (vtxIndx - 4);    // vertex 0
    }

   [self addChild:pMeshNode]; 

Answer 1

I think the problem is you need to supply vertex normals for your mesh. Normals are required for the lighting calculations to operate correctly. The routines to automatically populate a sphere, etc. are generating and storing vertex normals in the mesh. Desktop OpenGL will generate normals for a mesh without them when you use glEnable(GL_AUTO_NORMAL), but this functionality doesn't exist in mobile, at least not in OpenGL ES 2.0.