I've tried every DefaultVertexFormat and none of them seem to work, I'm just trying to accomplish the simple goal of drawing a half transparent square. Any help and explanation is appreciated so I know for the future.

 

@Override public void drawScreen(int mouseX, int mouseY, float partialTicks) {
	Tessellator tessellator = Tessellator.getInstance();
	WorldRenderer worldRenderer = tessellator.getWorldRenderer();
	GlStateManager.color(1F, 1F, 1F, 1F);
	worldRenderer.begin(7, DefaultVertexFormats.POSITION_COLOR);
	worldRenderer.pos(200, 20, this.zLevel).color(0, 0, 0, 0.5F).endVertex();
	worldRenderer.pos(20, 20, this.zLevel).color(0, 0, 0, 0.5F).endVertex();
	worldRenderer.pos(200, 200, this.zLevel).color(0, 0, 0, 0.5F).endVertex();
	worldRenderer.pos(20, 200, this.zLevel).color(0, 0, 0, 0.5F).endVertex();
	tessellator.draw();
	super.drawScreen(mouseX, mouseY, partialTicks);
}

Well, you want mode 7 because that's GL11.GL_QUADS which is squares.

 

Your problem is likely that you're trying to draw this square at a location in the world* and it's huge.  Also note that a quad is only visible from one side.  In this case, the north side.  If you're trying to draw to pixel locations on the screen,* then it would be pointed away from the camera.

 

*I'll admit that I'm not entirely sure what getWorldRenderer() does.

Yea Gui rendering changed a lot from 1.8 - > 1.8.8/1.8.9 Although the class is called "WorldRenderer" it is also used for things such as GUIs, I've looked at vanilla code and this is the method for drawBackground

 

    public void drawBackground(int tint)
    {
        GlStateManager.disableLighting();
        GlStateManager.disableFog();
        Tessellator tessellator = Tessellator.getInstance();
        WorldRenderer worldrenderer = tessellator.getWorldRenderer();
        this.mc.getTextureManager().bindTexture(optionsBackground);
        GlStateManager.color(1.0F, 1.0F, 1.0F, 1.0F);
        float f = 32.0F;
        worldrenderer.begin(7, DefaultVertexFormats.POSITION_TEX_COLOR);
        worldrenderer.pos(0.0D, (double)this.height, 0.0D).tex(0.0D, (double)((float)this.height / 32.0F + (float)tint)).color(64, 64, 64, 255).endVertex();
        worldrenderer.pos((double)this.width, (double)this.height, 0.0D).tex((double)((float)this.width / 32.0F), (double)((float)this.height / 32.0F + (float)tint)).color(64, 64, 64, 255).endVertex();
        worldrenderer.pos((double)this.width, 0.0D, 0.0D).tex((double)((float)this.width / 32.0F), (double)tint).color(64, 64, 64, 255).endVertex();
        worldrenderer.pos(0.0D, 0.0D, 0.0D).tex(0.0D, (double)tint).color(64, 64, 64, 255).endVertex();
        tessellator.draw();
    }

 

So I don't need .tex as my GUI element isn't textured. Like I don't see much difference in the two. If you can think of a case in vanilla where just a box is drawn on screen without a texture, I'll take a look at that (I also looked at tooltips yet that didn't seem to help either)

 

Edit: I probably should have searched more before giving up. I scrolled through the Gui class and there's a drawRect static method that takes 4 corners and a color.

Yea Gui rendering changed a lot from 1.8 - > 1.8.8/1.8.9 Although the class is called "WorldRenderer" it is also used for things such as GUIs

 

Some of the names MCP has given things are just weird.