OpenGL ES2 : Vertex Indices and Texture coordinates?

Question

I am using Vertex Indices to render my mesh.I have no problem passing vertex-indices and vertex positions.

But I am wondering in the case of texture coordinates,should I pass them them using Indices too?

Edit : I am trying to pass and render OBJ file and confused on how to handle texture coordinates described in "f x/y/z"

For example in the case of a Cube I pass my vertex coordinates :

*8 Vertex coords

*36 Vertex Indices:

When passing textures(or even normals) should I pass them as:

*(8 texture coords+36 texture coordinate indices). If so, how to assign them during render ?

or

*(36 texture coordinates) ?

This is my abstract mesh class,

public class AbstractMesh3D {
    //private int buffers[]={0,0};
    private int vbVertices[]=new int[1];
    private int vbIndices[]=new int[1];
    private int vbNormals[]=new int[1];
    private int vbColors[]=new int[1];
    private int vbTextureCords[]=new int[1];
    private boolean bVertices=false;
    private boolean bIndices=false;
    private boolean bNormals=false;
    private int numOfVertices;
    private int numOfIndices;
    private int numOfNormals;
    private World3D _world;
    private String textureId;

    public void setTextureId(String textureId) {
        this.textureId = textureId;
    }




    public AbstractMesh3D(){


    }
    public void setWorld(World3D world){
        this._world=world;
    }
    public void setVertexBuffer(float vertexData[]){
        GLES20.glGenBuffers(1, vbVertices, 0);
        //Short
        FloatBuffer vertexFloatBuffer=ByteBuffer.allocateDirect(vertexData.length*4).order(ByteOrder.nativeOrder()).asFloatBuffer();
        vertexFloatBuffer.put(vertexData);
        vertexFloatBuffer.position(0);

        //GLES20.glGenBuffers(1, vbVertices, 0);
        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, vbVertices[0]);
        GLES20.glBufferData(GLES20.GL_ARRAY_BUFFER, vertexData.length*4, vertexFloatBuffer, GLES20.GL_STATIC_DRAW);
        numOfVertices=vertexData.length/3;
        bVertices=true;

        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);
        GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, 0);


        //vertexFloatBuffer.
    }

    public void setNormalBuffer(float normalData[]){
        GLES20.glGenBuffers(1, vbNormals, 0);
        //Short
        FloatBuffer vertexFloatBuffer=ByteBuffer.allocateDirect(normalData.length*4).order(ByteOrder.nativeOrder()).asFloatBuffer();
        vertexFloatBuffer.put(normalData);
        vertexFloatBuffer.position(0);

        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, vbNormals[0]);
        GLES20.glBufferData(GLES20.GL_ARRAY_BUFFER, normalData.length*4, vertexFloatBuffer, GLES20.GL_STATIC_DRAW);
        bNormals=true;
        numOfNormals=normalData.length/3;

        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);
        GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, 0);

    }

    public void setIndices(short indices[]){
        GLES20.glGenBuffers(1, vbIndices, 0);
        ShortBuffer vertexFloatBuffer=ByteBuffer.allocateDirect(indices.length*2).order(ByteOrder.nativeOrder()).asShortBuffer();
        vertexFloatBuffer.put(indices);
        vertexFloatBuffer.position(0);

        //GLES20.glGenBuffers(1, buffers[1], 0);
        GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, vbIndices[0]);
        GLES20.glBufferData(GLES20.GL_ELEMENT_ARRAY_BUFFER, indices.length*2, vertexFloatBuffer, GLES20.GL_STATIC_DRAW);
        numOfIndices=indices.length;
        bIndices=true;

        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);
        GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, 0);

    }

    public void render(){
        int posHandle=_world.getOgl_aPositionHandle();
        int normalHandle=_world.getOgl_aNormalHandle();

        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, vbVertices[0]);
        GLES20.glEnableVertexAttribArray(posHandle);
        GLES20.glVertexAttribPointer(posHandle, 3, GLES20.GL_FLOAT, false, 12, 0);

        if(bNormals){
            GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, vbNormals[0]);
            GLES20.glEnableVertexAttribArray(normalHandle);
            GLES20.glVertexAttribPointer(normalHandle, 3, GLES20.GL_FLOAT, false, 12, 0);
        }

        if(bIndices){   
            //System.out.println("render indices");
            GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, vbIndices[0]);

            GLES20.glDrawElements(GLES20.GL_TRIANGLES, numOfIndices, GLES20.GL_UNSIGNED_SHORT, 0);          

        }else{
            GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, numOfVertices);
        }
        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);
        GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, 0);

        GLES20.glDisableVertexAttribArray(posHandle);
        GLES20.glDisableVertexAttribArray(normalHandle);
        //System.out.println("rendered");





    }

}

Answer 1

You must reorder the texcoords and vertices such that they share the same index. You cannot use a separate index for different attributes.

Always the number of vertices must equal number of texcoords must equal number of normals, etc.

When parsing OBJ this will involve duplicating some vertices/texcoords such that you can meet this requirement.