private int loadShader (int type, String source) {
GL20 gl = Gdx.graphics.getGL20();
IntBuffer intbuf = BufferUtils.newIntBuffer(1);
int shader = gl.glCreateShader(type);
if (shader == 0) return -1;
gl.glShaderSource(shader, source);
gl.glCompileShader(shader);
gl.glGetShaderiv(shader, GL20.GL_COMPILE_STATUS, intbuf);