Method initFBOLayerGL

core/src/processing/opengl/PJOGL.java:321–354

()

  private void initFBOLayerGL() {
    // Copy the contents of the front and back screen buffers to the textures
    // of the FBO, so they are properly initialized. Note that the front buffer
    // of the default framebuffer (the screen) contains the previous frame:
    // https://www.opengl.org/wiki/Default_Framebuffer
    // so it is copied to the front texture of the FBO layer:
    if (pclearColor || 0 < pgeomCount || !sketch.isLooping()) {
      if (hasReadBuffer()) readBuffer(FRONT);
    } else {
      // ...except when the previous frame has not been cleared and nothing was
      // rendered while looping. In this case the back buffer, which holds the
      // initial state of the previous frame, still contains the most up-to-date
      // screen state.
      readBuffer(BACK);
    }
    bindFramebufferImpl(DRAW_FRAMEBUFFER, glColorFbo.get(0));
    framebufferTexture2D(FRAMEBUFFER, COLOR_ATTACHMENT0,
                         TEXTURE_2D, glColorTex.get(frontTex), 0);
    if (hasDrawBuffer()) drawBuffer(COLOR_ATTACHMENT0);
    blitFramebuffer(0, 0, fboWidth, fboHeight,
                    0, 0, fboWidth, fboHeight,
                    COLOR_BUFFER_BIT, NEAREST);

    readBuffer(BACK);
    bindFramebufferImpl(DRAW_FRAMEBUFFER, glColorFbo.get(0));
    framebufferTexture2D(FRAMEBUFFER, COLOR_ATTACHMENT0,
                         TEXTURE_2D, glColorTex.get(backTex), 0);
    drawBuffer(COLOR_ATTACHMENT0);
    blitFramebuffer(0, 0, fboWidth, fboHeight,
                    0, 0, fboWidth, fboHeight,
                    COLOR_BUFFER_BIT, NEAREST);

    bindFramebufferImpl(FRAMEBUFFER, 0);
  }


  @Override