TextMesh Pro What is USE_DERIVATIVE in TMPro_Surface.cginc?

Around line 14 in TMPro_Surface.cginc there is the directive

#if USE_DERIVATIVE

What is the intent of this directive? Is it actually defined anywhere? All of my google searching only turns up the Text Mesh Pro cginc files.

 

This was a potential option to use Screen Space Derivative or SSD which is functionality that is now available in the TMP shaders with the SSD suffix at the end of their names.

With the normal shaders, we need to pass scale to the shader whenever the scale of the text object or its parent changes. With SSD shader we don't need to do that but it comes at a higher performance cost in the shader. So conveniences vs. efficiency. For text objects that won't change scale, the normal shaders are more efficient.

These SSD shaders are contained in the TMP Essential Resources.

 

That would be TMP_SDF SSD.shader and TMP_SDF-Mobile SSD.shader? So what you're saying is the USE_DERIVATIVE option is no longer used by the surface shader?

 

Correct.