Android, OpenGL convert vertices values to pixels

I'm creating application to Android using OpenGL开发者_运维百科 ES.

I created rectangle using following vertices.

private float vertices[] = {
          -1.0f,  0.5f, 0.0f,  // 0, Top Left
          -1.0f, -0.5f, 0.0f,  // 1, Bottom Left
           1.0f, -0.5f, 0.0f,  // 2, Bottom Right
           1.0f,  0.5f, 0.0f,  // 3, Top Right
    };

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

How do find location in pixels for this rectangle.

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It depends on your viewport, projection and model view matrices. position of a vertex on the screen is calculated with the formula like: projectionMatrix * modelviewMatrix * vertex

find some useful explanations here: http://robertokoci.com/world-view-projection-matrix-unveiled/ http://db-in.com/blog/2011/04/cameras-on-opengl-es-2-x/