Passing an image texture to each instance when using instance geometry

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Good day everyone.
I was learning about instancing to optimize scenes using the same geometry with instance geometry.
My issue is I’m cloning a plane geometry for my instance then for each instance of the geometry I want to pass a different image but since all the instances of the geometry use the same material I don’t know how to go about it also I can’t pass textures in attributes so please how do I go about it?

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When using instancing (for example, with Three.js’s InstancedMesh) you share the same geometry and material across many instances. That means you cannot directly assign a different texture to each instance because the texture is defined as a uniform on the material.

A common solution is to use a texture atlas. Here’s the general approach:

  1. Combine your images into one atlas:
    Merge all the different images you want to use into a single large texture (the texture atlas).
  2. Pass per-instance UV offsets:
    For each instance, supply extra data (using an instanced attribute) that specifies the offset (and possibly scale) of the UV coordinates. This tells the shader which part of the atlas to use.
  3. Modify the shader:
    In your vertex shader (or via material.onBeforeCompile() in Three.js) adjust the UV coordinates by adding the per-instance offset. Then, in the fragment shader, when sampling the texture, you’ll get the correct sub-image from the atlas for that instance.

An alternative (if your platform supports it) is to use array textures (available in WebGL2) where each instance could sample from a different layer. However, the texture atlas approach is more common and widely supported.

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