> For the complete documentation index, see [llms.txt](https://docs.hology.app/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.hology.app/assets/materials/transparency.md).

# Transparency

Transparent materials allow you to see through a mesh. Transparency can be **partial** (e.g. glass) or **binary** (fully visible or fully invisible per pixel). Choosing the correct method is important for both visual quality and performance.

There are two main approaches:

### Transparent Blending

Enable transparency by setting the material’s **Transparent** toggle to *Yes*. The final pixel color is blended with what has already been rendered behind it, using a blend mode (e.g. alpha blending).

**Pros**

* Supports **partial transparency** (smooth transitions between opaque and transparent)
* Ideal for materials like glass, water, smoke, and UI elements

**Cons**

* **Requires correct rendering order** (back-to-front sorting). Incorrect order can cause visible artifacts
* **Performance cost**: Objects behind must still be rendered even if fully covered
* Can produce **visual errors** when transparent objects overlap or intersect

**Use when**

* You need smooth, semi-transparent effects
* Visual accuracy is more important than performance

### Alpha Testing (Cutout)

Alpha testing uses a threshold to decide whether a pixel is rendered or discarded.

Example:\
If the alpha threshold is **0.1**, pixels with alpha < 0.1 are discarded; others are fully opaque.

**Pros**

* No sorting issues (renders like opaque objects)
* **Better performance** than blending in many cases
* Works well with depth testing and shadows

**Cons**

* No partial transparency (hard cut between visible/invisible)
* Can produce **jagged or pixelated edges**

**Tips**

* Adjust the threshold to minimize harsh edges
* Use higher-resolution textures or dithering techniques to improve appearance

**Use when**

* You need sharp cutouts (foliage, fences, grates)
* Performance and stability are important

### Quick Comparison

| Feature              | Transparent Blending | Alpha Test    |
| -------------------- | -------------------- | ------------- |
| Partial transparency | ✅ Yes                | ❌ No          |
| Sorting required     | ⚠️ Yes               | ❌ No          |
| Performance          | ❌ Higher cost        | ✅ Lower cost  |
| Edge quality         | ✅ Smooth             | ⚠️ Hard edges |

### Rule of Thumb

* Use **Transparent Blending** for *glass, liquids, effects*
* Use **Alpha Test** for *foliage, cutout textures, thin geometry*