It sounds silly but its true! Unity does not have any methods for resizing textures. Experienced readers might object, “what about Texture2D.Resize?” you say. Well, turns out that Texture2D.Resize only resizes the texture container, like trimming an array. Unlike trimming an array, Texture2D.Resize also sets the pixels to undefined. So really, all its doing is changing the amount of memory allocated. Thats all a bit disappointing, especially when you might be wanting to build a multi resolution pipeline for mobile. The weird thing is that Unity does this already when generating mip maps. So, lets roll up the old sleeves and figure this out.

We can get pixel data from texture, check! We can alter the pixel data, check! We can put pixel data into a texture, check! So whats left? The algorithm to resample pixel data. Resample is really the operative word because we are going to sample the source texture from the destination texture, pixel by pixel. This is exactly how pixel shaders work. So, We have our source texture at 1024×1024 and a destination texture at 512×512. What we are going to do is iterate through that 512×512 grid, find the corresponding color from the source texture and fill out destination pixel. Now we get to words you might have heard but never have known what they meant. Bilinear sampling is most common in games and gives a good understanding of how to sample but we are going to start with a technique called Nearest Neighbor. Resampling is mapping one set of coordinates onto another. So…