Push/Pop matrix mode after switching framebuffer

[Kirdow]

Hello. So I've been working on this mod for just around 2 years, and currently I'm adding a feature where items with a specific rarity glow just like with spectre arrow in the rarity of the item. Just a disclaimer, the project I work for is closed source so I wont be able to link to the git repo, but I do have in fact narrowed it down to a single OpenGL feature which shouldn't require my original source.

 

So back to the topic, I do have this feature 100% working and so I'm not here with help for that. Currently, my problem is maintaining compatibility with my previous features. Basically I have a lock item system where you can lock the items and not drop them. These items are indicated by a lock texture in the top right corner of the item slot, overlaying some of the item. Now getting the glow requires using shaders, which in turn requires a separate framebuffer, atleast to my knowledge. The system took just over a day to get working flawlessly, until I wanted to render the locks again, and noticed they are at the wrong location of the screen, which is the top left corner.

 

Having had this type of problem before I knew it was the scaling (from Gui Scale in video settings) reset, and I assumed it would be in the glow render code so I commented that out, built the code (Gotta love IntelliJ HotSwap <3), and noticed that the lock did indeed pop back to where they belong. After this it was just a matter of closing down the code step by step until I had only one part. I found last call made by me affecting the problem was Framebuffer#framebufferRenderExt. Now from reading help threads I knew this wasn't enough so I looked in the method and saw 2 key components. Resetting the view mode (in this case Orthographic), and resetting the viewport. I went into my main code for the gui rendering again and commented out the glow code call, and as a test, added a reset for orthographic just to test my theory and indeed that was the source of the problem. Just for reference this is a small illustration of my method at that point

@Override
public void drawScreen(int mouseX, int mouseY, float partialTicks) {
  // irrelevant code
  
  GL11.glPushMatrix();
  GL11.glMatrixMode(GL11.GL_PROJECTION);
  GL11.glLoadIdentity();
  GL11.glOrtho(0, mc.displayWidth, mc.displayHeight, 0, 1000f, 3000f);
  GL11.glMatrixMode(GL11.GL_MODELVIEW);
  GL11.glLoadIdentity();
  //RarityGlow.renderGlow(this);
  GL11.glPopMatrix();
  
  renderLocks();
}

Now my first thought was to somehow push the matrix mode or view, and thought of glPushAttrib. I looked up the problem on google, both for forge and in general, and found that pushing GL_TRANSFORM_BIT and GL_VIEWPORT_BIT should do the trick. I did try this, but that didn't work. So my current concern is, how would I go ahead and push/pop (or similar) the state in order to solve this said problem?

 

Edit: Also noting this is 1.12 which means Java 1.8. Forgot to mention that.

Edited June 15, 2018 by Kirdow