The HudElement Engine

Every piece of data on the HUD is a first-class citizen called a HudElement. This interface gives you total control over the rendering pipeline.

The HudElement Interface

I've designed the element system to be functional and lightweight. An element is responsible for two things: identifying itself and rendering its content while returning the vertical space it occupied.

HudElement.java

public interface HudElement {
    Identifier getId();
    
    // Returns the height (in pixels) that this element consumed
    int render(DrawContext context, MinecraftClient client, ItemStack stack, 
               int x, int y, int maxWidth, float alpha, float ageSinceEquip);
}

Parameter Breakdown

Parameter	Purpose
`x, y`	The absolute screen coordinates where your element should start drawing.
`maxWidth`	The boundary you should not exceed to maintain HUD visual integrity.
`alpha`	The 0.0-1.0 transparency value. You must apply this to your colors.
`ageSinceEquip`	Total ticks since the item was held. Perfect for time-based animations.

Default Elements Reference

I've provided several built-in elements that you can reuse or extend. These are located in com.itemglow.elements.DefaultElements.

NameLineElement

Handles the primary item name rendering, including rarity colors and automatic font scaling for long names.

DurabilityBarElement

Renders the health bar and durability text (e.g., "240 / 250") with color-shifting logic.

EnchantRowElement

The heavy lifter that renders enchantments, potion effects, and food data using the "Pill" system.

Working Example: Pulsing Mana Bar

This is a complete, working example of an element that renders a blue mana bar that pulses when the player's mana (a hypothetical component) is low.

ManaBarElement.java

public static class ManaBarElement implements ItemGlowApi.HudElement {
    @Override
    public Identifier getId() { return Identifier.of("mymod", "mana_bar"); }

    @Override
    public int render(DrawContext ctx, MinecraftClient client, ItemStack stack, 
                      int x, int y, int mW, float alpha, float age) {
        
        float mana = 0.3f; // Scraped from your mod's data
        int a = (int)(alpha * 255);
        
        // Calculate pulse effect using 'age'
        float pulse = mana < 0.4f ? (MathHelper.sin(age * 0.5f) + 1.0f) * 0.5f : 0.0f;
        int color = (a << 24) | (int)(pulse * 100) << 16 | 0x55AAFF;

        // Draw the background and bar
        ctx.fill(x, y + 2, x + mW, y + 4, (a / 2 << 24) | 0x222222);
        ctx.fill(x, y + 2, x + (int)(mW * mana), y + 4, color);

        return 6; // We used 6 pixels of height
    }
}

Figure 1.0: A custom Mana Bar element integrated into the Item Glow HUD, showing a low-mana pulse effect.

Registration

Once you've created your HudElement, you need to tell Item Glow where to render it. You can either create a completely new layout (see HUD Panels) or simply append your element to the default HUD.

Registration Code

// 1. Get the default panel
HudPanel def = ItemGlowApi.getPanel(Identifier.of("itemglow", "default"));

// 2. Append your element
if (def != null) {
    def.addElement(new ManaBarElement());
}