// My GLSurfaceView.Renderer class

    @Override
    public void onDrawFrame(GL10 unused) {

        // draw background color
        GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);

        Matrix.setLookAtM(this.modelViewMatrix, 0, 0, 0, this.eyeZ, 0f, 0f, 0f, 0f, 1.0f, 0.0f);
        Matrix.multiplyMM(this.mvpMatrix, 0, this.projectionMatrix, 0, this.modelViewMatrix, 0);

        Square s = new Square();
        s.draw(this.mvpMatrix);
    }

    @Override
    public void onSurfaceChanged(GL10 unused, int width, int height) {
        GLES20.glViewport(0, 0, width, height);
        ratio = (float) width / height;
        Matrix.frustumM(this.projectionMatrix, 0, -ratio, ratio, -1, 1, 50, 70);
    }


    // My shaders

    public static final String vertexShaderCode =
                    "uniform mat4 mvpMatrix;" +
                    "attribute vec4 positionVector;" +
                    "void main() {" +
                    "   gl_Position = positionVector * mvpMatrix;" +
                    "}";

    public static final String fragmentShaderCode =
            "precision mediump float;" +
                    "uniform vec4 colorVector;" +
                    "void main() {" +
                    "   gl_FragColor = colorVector;" +
                    "}";


    //  Draw method for the square that I see

    public void draw(float[] mvpMatrix) {
        FloatBuffer vertexBuffer = this.calculateVertexBuffer();

        GLES20.glUseProgram(program);
        this.positionHandle = GLES20.glGetAttribLocation(program, "positionVector");
        GLES20.glEnableVertexAttribArray(this.positionHandle);

        GLES20.glVertexAttribPointer(
                this.positionHandle,
                this.coordsPerVertex,
                GLES20.GL_FLOAT,
                false,
                this.vertexStride,
                vertexBuffer
        );

        this.coloHandle = GLES20.glGetUniformLocation(this.program, "colorVector");
        GLES20.glUniform4fv(this.coloHandle, 1, this.color, 0);

        this.mvpMatrixHandle = GLES20.glGetUniformLocation(this.program, "mvpMatrix");
        UtilOpenGL.checkGlError("glGetUniformLocation");

        GLES20.glUniformMatrix4fv(this.mvpMatrixHandle, 1, false, mvpMatrix, 0);
        UtilOpenGL.checkGlError("glUniformMatrix4fv");

        GLES20.glDrawElements(
                GLES20.GL_TRIANGLES,
                drawOrder.length,
                GLES20.GL_UNSIGNED_SHORT,
                drawListBuffer
        );

        GLES20.glDisableVertexAttribArray(this.positionHandle);
    }