FlexHUD

An extensible HUD layout and rendering library built on NeoForge. It uses “RelativeRect + Anchor” to describe HUD element positions and sizes in a resolution‑independent way, provides an interactive config screen for drag/resize with constraints, and persists layout to client config while auto‑recomputing on screen size changes.

Goals

• Describe HUD element position and size via RelativeRect and Anchor so layouts are stable across resolutions/aspect ratios.
• Expose a simple registration API: implement Layer#render to plug in your custom HUD element.
• Provide a visual configuration screen (FlexHudConfigScreen): drag to move, resize with handles; ResizeMode controls constraints (Free, Aspect, Horizontal, Vertical, Fixed).
• Persistence and hot‑update: use NeoForge ModConfig to store and sync positions; changes apply immediately at runtime.

Quick Start

Register a freely resizable Hotbar HUD element:

public class BuiltInFlexHud {
    public static void registerHotbarHud() {
        ResourceLocation id = FlexHudApi.HOTBAR_ID; // unique element ID

        // Default relative rect: bottom-center anchor, width 182, height 22
        FlexHudApi.RelativeRect defaultRelativeRect = new FlexHudApi.RelativeRect(
                FlexHudApi.Anchor.BOTTOM_CENTER,
                0, 0,
                182, 22
        );

        // Render layer: draw using the computed absolute rect
        FlexHudApi.Layer hotbarLayer = (rect, guiGraphics, deltaTracker) -> {
            PoseStack pose = guiGraphics.pose();
            pose.pushPose();

            int screenWidth = guiGraphics.guiWidth();
            int screenHeight = guiGraphics.guiHeight();
            // Compute the vanilla hotbar default absolute rect from the default relative rect
            FlexHudApi.Rect defaultRect = defaultRelativeRect.toAbsolute(screenWidth, screenHeight);
            // Apply affine transform from defaultRect to the target rect for free move/scale
            pose.mulPose(defaultRect.transform(rect));

            ((GuiAccessor) Minecraft.getInstance().gui).callRenderHotbar(guiGraphics, deltaTracker);
            pose.popPose();
        };

        // Register with Free resize mode using the default relative rect and layer
        FlexHudApi.INSTANCE.register(id, FlexHudApi.ResizeMode.Free, defaultRelativeRect, hotbarLayer);
    }
}

At runtime, the library calls updateScreenDimensions() before rendering to convert each element’s RelativeRect into an absolute Rect for the current resolution and passes it to your Layer#render.

API Overview

• FlexHudApi#register(ResourceLocation id, ResizeMode mode, RelativeRect defaultRect, Layer layer)
  • Register a HUD element; if a saved layout exists in config, it overrides the default.
• FlexHudApi.Impl#updateElementRelativeRect(ResourceLocation id, RelativeRect newRect)
  • Update layout at runtime and persist; the config screen uses this.
• FlexHudApi.Impl#updateScreenDimensions()
  • Recompute all absolute rects when screen size/aspect changes.
• FlexHudApi.Layer#render(Rect rect, GuiGraphics g, DeltaTracker dt)
  • Render callback: draw using the provided absolute rect.
• FlexHudApi.ResizeMode
  • Free, Aspect (keep ratio), Horizontal, Vertical, Fixed.
• FlexHudApi.Anchor
  • Nine‑grid anchors: TOP_LEFT / TOP_CENTER / TOP_RIGHT / CENTER_LEFT / CENTER / CENTER_RIGHT / BOTTOM_LEFT / BOTTOM_CENTER / BOTTOM_RIGHT.
• FlexHudApi.RelativeRect
  • Fields: anchor, offsetX, offsetY, width, height, useRelativeSize
  • Methods: toAbsolute(int w, int h) to convert to absolute; fromAbsolute(Rect rect, Anchor a, int w, int h) to infer relative.
• FlexHudApi.Rect#transform(Rect to)
  • Affine transform from source rect to target rect (translate + scale) to map existing drawing logic to the new position/size.

Visual Configuration

• Press Alt + H in game to open FlexHudConfigScreen.

• Drag to move, resize with handles; ResizeMode determines constraints.

• Changes are persisted to client config (NeoForge ModConfig), e.g.:

  [hud]
  relative_rects = [
    "flexhud:hotbar|BOTTOM_CENTER|-2.9042664|-37.03853|188.19147|22.961472|false"
  ]
  

Requirements

• Minecraft 1.21.1
• NeoForge 21.x (e.g. 21.1.213)
• Java 21

License

• MIT (see build script / project config).