var mvMatrix;
var mvMatrixStack = [];
function mvPushMatrix(m)
{
    if (m) {
      mvMatrixStack.push(m.dup());
      mvMatrix = m.dup();
    } else {
      mvMatrixStack.push(mvMatrix.dup());
    }
}

function mvPopMatrix()
{
    if (mvMatrixStack.length == 0) {
      throw "Invalid popMatrix!";
    }
    mvMatrix = mvMatrixStack.pop();
    return mvMatrix;
}

function multMatrix(m)
{
    mvMatrix = mvMatrix.x(m);
}

function mvTranslate(v)
{
    var m = Matrix.Translation($V([v[0], v[1], v[2]])).ensure4x4();
    multMatrix(m);
}

function mvRotate(ang, v)
{
    var arad = ang * Math.PI / 180.0;
    var m = Matrix.Rotation(arad, $V([v[0], v[1], v[2]])).ensure4x4();
    multMatrix(m);
}

function setMatrixUniforms()
{
    gl.uniformMatrix4fv(shaderProgram.pMatrixUniform, false, new Float32Array(pMatrix.flatten()));
    gl.uniformMatrix4fv(shaderProgram.mvMatrixUniform, false, new Float32Array(mvMatrix.flatten()));
}