@Override
public void display() {
gl.glClear(GL3.GL_COLOR_BUFFER_BIT | GL3.GL_DEPTH_BUFFER_BIT);
// Calculate the model matrix ...
modelMatrix.loadIdentity();
// ... by rotating the cube.
modelMatrix.rotate(Maths.degToRad(15), new float[] {1, 0, 0});
modelMatrix.rotate(Maths.degToRad(angle), new float[] {0, 1, 0});
// MV = V * M
modelViewMatrix.multiply(viewMatrix, modelMatrix);
modelViewMatrix.bind();
// Again, extract the normal matrix.
// Remember, so far the model view matrix (rotation part) is orthogonal.
normalMatrix.extract(modelViewMatrix);
normalMatrix.bind();
// Extract the rotation part of the view matrix.
inverseViewMatrix.extract(viewMatrix);
// Pass this matrix to the shader with the transpose flag.
// As the view matrix is orthogonal, the transposed is the inverse view matrix.
inverseViewMatrix.bind(true);
cubeMap.bind();
model.bind();
model.draw(GL3.GL_TRIANGLES);
gl.glFlush();
update();
}