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CProgrammer

mixing fixed function and programmable pipeline

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Well the question is wether it is bad practice to draw some objects using the fixed function pipeline and others with the programmable one. Is it preferable to just implement a trivial shader for fixed function rendered objects? -CProgrammer

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I have a feeling those into shaders would say do everything that way. And I hear the FF pipeline no longer exists in DX10, though I don't know if this means you have to roll shaders to get anything on screen.

Personally I'd use FF if I wanted to get something rendered quickly, or something which would never nee more than diffuse colour and a single texture. But then I'm not practised with shaders so it would be quicker for me to do that. Maybe others could write a simple shader and use it faster than I code the renderstate settings etc?

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Be careful when mixing the two, as the depth values produced may vary slightly even when doing equivilent work. For GLSL the built-in ftransform() can be used to make sure it produces the same result, I can only assume that other shader languages provide an equivilent.

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ATI cards run everything through the programmable pipeline - the fixed pipeline is simulated with shaders. Because of this, the precision is always the same regardless.

Can't say the same for nVidia cards though.

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Quote:
Original post by MENTAL
ATI cards run everything through the programmable pipeline - the fixed pipeline is simulated with shaders. Because of this, the precision is always the same regardless.


however if you wrote the shader yourself then it might be better optimized.

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