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How do I make part of a texture transparent in Blender?

Published in Blender Texturing 5 mins read

To make part of a texture transparent in Blender, you typically use the texture's alpha channel or a separate grayscale image as an alpha mask and connect it to the Alpha input of your material shader, most commonly the Principled BSDF node.

Understanding Texture Transparency in Blender

Transparency in textures is controlled using an alpha channel. This is an extra layer of data in an image file (like PNG or TGA) that defines how transparent each pixel is.
Alternatively, you can use a separate grayscale image where white areas indicate full visibility (opaque) and black areas indicate full transparency. Shades of gray result in semi-transparency.

Using the Principled BSDF Node for Transparency

Blender's Principled BSDF shader is a versatile node used for creating a wide range of materials. It includes an Alpha input specifically designed to control transparency based on an external value.

As referenced, you can either use Principled BSDF with the Alpha value to control transparency... Where any grayscale white values entering the Alpha input will be visible, and black values will be transparent. This means:

  • White (1.0) in the Alpha input = Fully visible (opaque)
  • Black (0.0) in the Alpha input = Fully transparent
  • Grayscale values (0.0 - 1.0) = Semi-transparent

By connecting your texture's alpha output (or a separate mask image) to this Alpha input, you tell the material which parts should be see-through.

Essential Material Settings

Simply connecting the Alpha input isn't enough. You also need to tell Blender's rendering engine (Eevee or Cycles) how to handle the transparency. This is done in the Material Properties panel under the Settings tab.

  • Blend Mode: Change this from "Opaque" to one of the transparency modes:
    • Alpha Blend: Provides smooth transparency but can have sorting issues.
    • Alpha Hashed: Simulates transparency by hashing pixels, generally better for sorting but can look noisy.
    • Alpha Clip: Makes pixels either fully opaque or fully transparent based on a threshold, no semi-transparency.

You typically need to set the Blend Mode in both the Viewport Display settings (for preview) and the Eevee Settings or Cycles Settings sections.

Step-by-Step Guide

Here are the steps to make part of a texture transparent using a Principled BSDF material:

  1. Select the object you want to apply the transparent texture to.
  2. Go to the Shading workspace or tab.
  3. Select or create a new Material for the object. Ensure the main shader node is a Principled BSDF.
  4. Add an Image Texture node (Shift+A > Texture > Image Texture).
  5. Click Open in the Image Texture node and load your image file. If your image has an alpha channel (like a PNG with transparency), Blender will automatically detect it. If using a separate alpha mask, load the grayscale image here instead.
  6. Connect the Color output of the Image Texture node to the Base Color input of the Principled BSDF node.
  7. Crucially: Connect the Alpha output of the Image Texture node (if your main image has alpha) OR the Color output of your separate alpha mask Image Texture node to the Alpha input of the Principled BSDF node.
    • Tip: For the alpha mask image node, set its Color Space to Non-Color.
  8. Go to the Material Properties panel (usually on the right side).
  9. Scroll down to the Settings section.
  10. Under Viewport Display, change the Blend Mode from "Opaque" to Alpha Blend, Alpha Hashed, or Alpha Clip. This allows you to see transparency in the viewport.
  11. For rendering, scroll down to the Eevee Settings or Cycles Settings (depending on your render engine).
  12. Also change the Blend Mode in this section to match your Viewport Display setting (or choose a different one if desired).

Now, parts of your texture corresponding to black or low alpha values in the connected alpha source should appear transparent.

Tips for Effective Transparency

  • Always use image formats that support alpha channels (e.g., PNG, TGA).
  • Ensure your image texture node for the main color is set to sRGB Color Space.
  • If using a separate mask image, set its Image Texture node to Non-Color Data to ensure grayscale values are read correctly by the Alpha input.
  • Experiment with different Blend Modes in the Material Settings to find the best look and performance for your scene.

By following these steps and utilizing the Principled BSDF's Alpha input as described, you can effectively control texture transparency in Blender.

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