XNA and FBX Coloring Problem

My problem is that, if I use BasicEffect (and setup VertexColorEnabled = true) or my own shader, and use only colored (not textured!) models, it gives the error t开发者_运维知识库hat Color0 is missing...Isn't it weird that .fbx models do not come with COLOR0 channel ?

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Here is what I found..... (Marshall Belew @ forums.create.msdn.com/forums/p/16066/553792.aspx#553792) Saved my day...

The solution is simple: the BasicShader has a DiffuseColor property. I merely added a new field into the Toon shader, and any time there was no texture, I substituted the color value.

I am happier with this solution because now I don't have to write a ton of vertex declaration / draw primitive logic.

From the .fx file:

// Pixel shader applies a cartoon shading algorithm. 
float4 ToonPixelShader(LightingPixelShaderInput input) : COLOR0 
{ 
    float4 color = TextureEnabled ? tex2D(Sampler, input.TextureCoordinate) : DiffuseColor; 

Replacing the effects (this is a modified snipet from the NonPhotoRealistic sample).

// Scan over all the effects currently on the mesh. 
foreach (BasicEffect oldEffect in mesh.Effects) 
{ 
   // If we haven't already seen this effect... 
   if (!effectMapping.ContainsKey(oldEffect)) 
   { 
      // Make a clone of our replacement effect. We can't just use 
      // it directly, because the same effect might need to be 
      // applied several times to different parts of the model using 
      // a different texture each time, so we need a fresh copy each 
      // time we want to set a different texture into it. 
      Effect newEffect = replacementEffect.Clone( 
                                  replacementEffect.GraphicsDevice); 

      // Copy across the texture from the original effect. 
      newEffect.Parameters["Texture"].SetValue(oldEffect.Texture); 

      newEffect.Parameters["TextureEnabled"].SetValue( 
                                          oldEffect.TextureEnabled); 

      Vector4 color = new Vector4(oldEffect.DiffuseColor, 1.0f); 
      newEffect.Parameters["DiffuseColor"].SetValue(color); 

      effectMapping.Add(oldEffect, newEffect); 
   } 
}