Xna Content Pipeline and Textures

Question

I have tried to get my head around the content processor and textures, but I am a bit confused... I have 2 scenarios:

• One is a model that contains a texture, the importer loads the xml and passes the texture filename to the processor, but I can only get a TextureContent, which seems to be a compile time reference to a texture, but this doesn't help me populate the Texture2D bit of my model.

• The 2nd scenario is I want to piggyback of the texture processor to create a spritemap object from a texture file, the spritemap is basically a model which contains a texture and sprite width/height.

The thing that keeps getting me stumped is these ExternalReference and TextureContent, as the model, lets say:

public class SpriteMap
{
    public Texture2D Texture { get; private set; }
    public int SpriteWidth { get; private set; }
    public int SpriteHeight { get; private set; }

    public SpriteMap(Texture2D texture, int spriteWidth, int spriteHeight)
    {
        this.texture = texture;
        this.spriteWidth = spriteWidth;
        this.spriteHeight = spriteHeight;
    }
}

Then I have a content processor like so:

[ContentProcessor(DisplayName = "TextureToSpriteMapProcessor")]
public class TextureToSpriteMapProcessor : ContentProcessor<Texture2D, ISpriteMap>
{
    [DisplayName("Sprite Width")]
    [DefaultValue(64)]
    [Description("The size of each sprite's width within the sprite map.")]
    public virtual int SpriteWidth { get; set; }

    [DisplayName("Sprite Height")]
    [DefaultValue(64)]
    [Description("The size of each sprite's height within the sprite map.")]
    public virtual int SpriteHeight { get; set; }

    public override ISpriteMap Process(Texture2D input, ContentProcessorContext context)
    { return new SpriteMap(input, SpriteWidth, SpriteHeight); }
}

Now it complains that the processor is given a TextureContent, but that isn't a texture... but for some reason a TextureContent seems to magically turn into a Texture when it is loaded via the contentManager... so I am a bit baffled as to how I can get a texture in this instance. As both scenarios are fairly similar I am sure if I solve one I will solve them both, but ideally I want to be able to go:

contentManager.Load<ISpriteMap>("someTextureAsset");

If anyone can explain how to make this seemingly magic process work, I will give you much praise!

Answer 1

My main problem here was that I was trying to use the same model on both sides, the texture content is the compile time representation of the texture from my current understanding. So when I am in the compile-time domain of the Importer/Processor I can only work with these references and content data.

So to solve my problem I had to revert back to using TextureContent and not Texture2D, then make a model SpriteMapContent which contained the references to the textures in question and the other data required for the model. Then write a content reader/writer to govern how the data was put together in the run-time domain.

This similar post I made was what made it clearer to me where I was going wrong and what I needed to do to solve the problem.

https://gamedev.stackexchange.com/questions/22480/contentserializerruntimetype-required-in-content-pipeline/22482#22482

Answer 2

The basic concept of the content processor is to pack your assets into an intermediate state. XNB is what it usually creates. Its a binary file that can be loaded quickly into runtime. If you have a texture, it can be read in, have alpha removed, compressed into directx format, and then saved as a binary, which will be loaded at runtime. Your basic objective is to prep the TextureContent to be how you want it and then let the content processor base classes pack that into a binary format.

A great example of what you want to do is the Normal Map sample on XNA. A normal map defines the angle of each texel on a model without actually having a hi-poly model. The example lets you specify a texture, it then process the texture and attaches it to the model so you can get it later at runtime. It stores it in the Opaque Data list and also attaches it as a shader variable.