private void renderNightvisionOverlay(Minecraft minecraft)
{
    ItemStack itemstack = minecraft.thePlayer.inventory.armorItemInSlot(3);
    if(!minecraft.gameSettings.thirdPersonView && itemstack != null)
    {
        if(itemstack.itemID == itemNightvisionGoggles.shiftedIndex && nightvisionEnabled)
        {
            renderTextureOverlay(minecraft, "%blur%/misc/nightvision.png", 1F);
        }
    }
}

private void renderTextureOverlay(Minecraft mc, String texturePath, float alpha)
{
    ScaledResolution scaledresolution = new ScaledResolution(mc.displayWidth, mc.displayHeight);
    int width = scaledresolution.getScaledWidth();
    int height = scaledresolution.getScaledHeight();

    GL11.glEnable(3042 /*GL_BLEND*/);
    GL11.glDisable(2929 /*GL_DEPTH_TEST*/);
    GL11.glDepthMask(false);
    GL11.glBlendFunc(770, 771);
    GL11.glColor4f(1.0F, 1.0F, 1.0F, alpha);
    GL11.glDisable(3008 /*GL_ALPHA_TEST*/);
    GL11.glBindTexture(3553 /*GL_TEXTURE_2D*/, mc.renderEngine.getTexture(texturePath));
    Tessellator tessellator = Tessellator.instance;
    tessellator.startDrawingQuads();
    tessellator.addVertexWithUV(0.0D, height, -90D, 0.0D, 1.0D);
    tessellator.addVertexWithUV(width, height, -90D, 1.0D, 1.0D);
    tessellator.addVertexWithUV(width, 0.0D, -90D, 1.0D, 0.0D);
    tessellator.addVertexWithUV(0.0D, 0.0D, -90D, 0.0D, 0.0D);
    tessellator.draw();
    GL11.glDepthMask(true);
    GL11.glEnable(2929 /*GL_DEPTH_TEST*/);
    GL11.glEnable(3008 /*GL_ALPHA_TEST*/);
    GL11.glColor4f(1.0F, 1.0F, 1.0F, alpha);
}