How to handle multiple effect files in XNA
- by Adam 'Pi' Burch
So I'm using ModelMesh and it's built in Effects parameter to draw a mesh with some shaders I'm playing with. I have a simple GUI that lets me change these parameters to my heart's desire. My question is, how do I handle shaders that have unique parameters? For example, I want a 'shiny' parameter that affects shaders with Phong-type specular components, but for an environment mapping shader such a parameter doesn't make a lot of sense. How I have it right now is that every time I call the ModelMesh's Draw() function, I set all the Effect parameters as so
foreach (ModelMesh m in model.Meshes)
{
if (isDrawBunny == true)//Slightly change the way the world matrix is calculated if using the bunny object, since it is not quite centered in object space
{
world = boneTransforms[m.ParentBone.Index] * Matrix.CreateScale(scale) * rotation * Matrix.CreateTranslation(position + bunnyPositionTransform);
}
else //If not rendering the bunny, draw normally
{
world = boneTransforms[m.ParentBone.Index] * Matrix.CreateScale(scale) * rotation * Matrix.CreateTranslation(position);
}
foreach (Effect e in m.Effects)
{
Matrix ViewProjection = camera.ViewMatrix * camera.ProjectionMatrix;
e.Parameters["ViewProjection"].SetValue(ViewProjection);
e.Parameters["World"].SetValue(world);
e.Parameters["diffuseLightPosition"].SetValue(lightPositionW);
e.Parameters["CameraPosition"].SetValue(camera.Position);
e.Parameters["LightColor"].SetValue(lightColor);
e.Parameters["MaterialColor"].SetValue(materialColor);
e.Parameters["shininess"].SetValue(shininess);
//e.Parameters
//e.Parameters["normal"]
}
m.Draw();
Note the prescience of the example! The solutions I've thought of involve preloading all the shaders, and updating the unique parameters as needed. So my question is, is there a best practice I'm missing here? Is there a way to pull the parameters a given Effect needs from that Effect?
Thank you all for your time!
