Posted by Lathanda on Aug 04, 2010; 7:06am
URL: https://forum.jogamp.org/Transparent-Texture-tp1020455p1021617.html

I used the more manuall way, the only way you learn how things work :)

I change my code to
  gl.glEnable(GL.GL_BLEND);
  gl.glBlendFunc(GL.GL_ONE, GL.GL_ONE_MINUS_SRC_ALPHA);
  t.enable();
  t.bind();
  gl.glTexEnvi(GL2.GL_TEXTURE_ENV, GL2.GL_TEXTURE_ENV_MODE, GL2.GL_REPLACE);
  gl.glBegin(GL2.GL_QUADS);
    gl.glTexCoord2d(0.0,0.0); gl.glVertex2d(x, y);
    gl.glTexCoord2d(1.0,0.0); gl.glVertex2d(x+width, y);
    gl.glTexCoord2d(1.0,1.0); gl.glVertex2d(x+width, y+height);
    gl.glTexCoord2d(0.0,1.0); gl.glVertex2d(x, y+height);
  gl.glEnd();
  t.disable();
  gl.glDisable(GL.GL_BLEND);
And now it's working as intended.
Thank you for your hint.