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Overview of Physically Based Rendering

Physically Based Rendering, or PBR, simulates how materials would react to realistic light behavior. Metallic surfaces cast reflections; light bends and refracts through different types of glass. For objects you create to take advantage of PBR, you'll need to create special textures that capture properties of the material, such as metallic properties, emissive properties, and roughness (often abbreviated together as "MER").

By the end of this overview, you'll learn:

  • The new texture maps available in Minecraft: Bedrock Edition.
  • The basic workflows when designing PBR textures for Minecraft.
  • How to create a mirror texture set using roughness and metallic maps.

Prerequisites

It'll be helpful to have read the Introduction to Resource Packs before reading this document. You'll need a ready-to-go Resource Pack with the textures/blocks folder structure set up.

While we'll provide textures to download, you'll need to have some digital painting software that has layers to create your textures, such as the Windows 11 version of Microsoft Paint, Adobe Photoshop, or PaintTool SAI.

What makes a PBR texture?

In Minecraft, 3D blocks are given detail by applying 2D images to them using a common rendering method called Texture Mapping. Standard Minecraft blocks use a single texture map, an image with four color channels: Red, Blue, Green, and Alpha (RGBA). Most image editors work with RGBA images: the first three channels provide the color for each image pixel, while the alpha channel controls that pixel's transparency level.

PBR introduces five new maps for textures that set values for different kinds of properties for each pixel in the color map:

Together, these maps give you a great deal of control over how blocks you add to your resource packs are rendered when placed in the world. Let's look at each kind of map in turn.

Important

Not all PBR texture sets require all maps. Leaving empty maps will cause the texture set to use the default value.

Metalness map

A Metalness map is a grayscale texture that determines which areas of a texture map look like metal. The brighter the pixel is, the more metallic it will look.

  • A pixel set to pure black is completely non-metallic, with a value of 0.0. Grass, dirt, and tree bark are completely non-metallic objects.
  • A pixel set to pure white is completely metallic, with a value of 1.0. Iron, gold, and copper are examples of completely metallic objects.
  • Pixels between pure black and pure white will look more or less metallic, depending on how bright or dark they are.

concrete white block with metallic edges and a matte center

The above image uses the following metalness map:

concrete white block metallic mer texture

Emissive map

An Emissive map is a grayscale texture that determines which areas of a texture map emit light.

  • A pixel set to pure black is completely non-emissive (dark), with a value of 0.0.
  • A pixel set to pure white is completely emissive (glowing at its brightest), with a value of 1.0.
  • Pixels between pure black and pure white will glow more or less brightly, depending on how bright or dark they are.

concrete white block with vertical glowing stripes

The above image uses the following emissive map:

concrete white block emissive mer texture

Roughness map

A Roughness map is a grayscale texture that determines which areas of the texture map are smooth and which are rough.

  • A pixel set to pure black is as smooth as possible, with a value of 0.0. Smooth marble, glass, or smooth plastic are very smooth.
  • A pixel set to pure white is as rough as possible, with a value of 1.0. Brick, tree bark, and stones are very rough.
  • Pixels between pure black and pure white will look more or less rough, depending on how bright or dark they are.

concrete white block with horizontal rough and smooth stripes

The above image uses the following roughness map:

concrete white block roughness mer texture

Normal map

A Normal map is an RGB texture (not grayscale) that controls the depth and how light behaves when a light ray hits the texture. "Normal" refers to the concept of a surface normal in geometry, and the R, G, and B elements in the normal map correspond to the X, Y, and Z coordinates of the surface. Values of R (X) 128, G (Y) 128, and B (Z) 255 result in a flat appearance of the pixel.

Caution

Unless you have experience with creating Normal maps, it's recommended that you do not create Normal maps by hand. Third-party software is available to assist with creating Normal maps.

Height map

A Height map is a grayscale texture that controls depth of a texture. Height maps act as an alternative to Normal maps, but are not as efficient and cannot represent as many textures.

  • A pixel set to pure black extrudes inward as much as possible, with a value of 0.0.
  • A pixel set to pure white extrudes outward as much as possible, with a value of 1.0.
  • A pixel midway between pure black and pure white (127, 127, 127), with a value of 0.5, does not extrude in or out.

concrete white block that has ridges in a square pattern

The above image uses the following height map:

concrete white block height mer texture

Make a mirror

Let's create a mirror texture for an existing vanilla block by creating a Texture Set JSON file and using a provided texture file.

Make a texture set JSON

For the Texture Set to work properly, you will need to define a JSON file to load the textures. This tutorial is a mirror example working with the iron_block block.

Tip

To learn more about texture sets, please read Introduction to Texture Sets.

  1. In your behavior pack, navigate to the textures/blocks folder.
  2. Create a new .JSON file and name it iron_block.texture_set.json.
  3. Double-click on iron_block.texture_set.json to edit the contents.
  4. Copy the following example into the file:
{
    "format_version": "1.16.100",
    "minecraft:texture_set": {
    "color": "iron_block",
    "metalness_emissive_roughness": "iron_block_mer"
    }
}
  1. Save and close the file.

With the JSON file set up, you can now configure the textures for the color values and the metalness_emissive_roughness values.

Add the PBR capability

The manifest.json file for the pack requires the value "pbr" to be added in a capabilities section below your existing header and modules:

{
    "format_version": 1,
    "header": {
        "name": "RTX Sample Resources",
        "description": "",
        "uuid": "58d4560c-106d-4b0c-9847-eee47417fb05",
        "min_engine_version": [1, 12, 0],
        "version": [1, 0, 0]
    },
    "modules": [
        {
            "description": "",
            "type": "resources",
            "uuid": "2d3df25b-856a-406d-9a57-c87b9a4d7af8",
            "version": [0, 0, 1]
        }
    ],
    "capabilities" : [
        "pbr"
    ]
}

Add the textures

To create a mirror in a PBR workflow, you need a Roughness map and a Metalness map. A Roughness map with a value of 0.0, or solid black, will create a smooth surface for light to reflect off. A Metalness map set to a value of 1.0, or solid white, will render the block like reflective metal.

Download these two PNG files, iron_block.png (the color texture map) and iron_block_mer.png (the MER texture map), by right-clicking them and selecting Save image as:

  • iron_block.png
  • iron_block_mer.png

Copy and paste both .png files into the textures/blocks folder.

Run the texture pack

With the JSON file properly set up and both textures in place, you can now load in your texture pack to test in Minecraft.

iron block reflecting flowers from the environment

What's next?