I could tell you.... but Id have to kill you
Seriously though, its common in every 3d engine to have ways of manipulating UV coordinates and the range of values they can use.
AGK Documentation wrote: "
Mipmapping
Using SetGenerateMipmaps(1) to turn mipmapping on uses 33% more memory for images than turning it off but it can remove filtering artifacts created when using high resolution images on 3D objects or on objects that are far away. Therefore it may be beneficial to turn it on for 3D apps even though it uses more memory. However any images loaded whilst this is turned on must be a power of 2 in size, i.e. the image width and height must one of the following values 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048. The image does not need to be square, i.e. it could be 1024x256."
https://www.appgamekit.com/documentation/tips.html
So.....the documentation does cover the fact that
if you want to use mipmapping then your images should be a power of 2 in size.
What it doesnt state, is that you can use non power of 2 textures and mipmapping... BUT you just have to be careful especially with using your own shaders. You cant do any UV scrolling if you do this. A custom shader can be used as long as you use the textureBounds variable in your code so that it limits the UV coordinates to the actual sub area on the texture where your image is. You could even alter the UV coordinates of the quad to do the same thing if you wanted via a memblock. AppGameKit fills in the values for textureBounds automatically so you dont need to worry about what they are as long as you use it. Its like using a sub image on a 3d object. Only a small range of the 0-1.0 uv range is used on the 3d primative.
Its often easier to just resize the image externally to a power of 2 to get round this or use ResizeImage() in AppGameKit to do it. If its a power of 2 you dont need to do anything special.
You can look at the internally generated pixel shader code with commands in AppGameKit so you can see what it does and what variables are used to scale the UV's to what they should be if you wanted so you get to pick up on what to look for and what to do in a custom shader.
