Update DepthTexture - Is it 'free' on any platforms?

Hey guys

The documentation says:

Does this mean the depth texture is 'free' on certain hardware? When I run the framedebugger in the editor, regardless of whether I am doing forward or deferred, I get a whole lot more drawcalls as unity needs to do a seperate pass for the depth buffer (Update DepthTexture).

Is this operation 'free' on when deployed on certain hardware? Can I access it in forward rendering?

 

Also, stated here:

http://docs.unity3d.com/Manual/UpgradeGuide5-Shaders.html

So, enabling shadows gives me a depth texture, too ?

 

Assuming:
Depth Texture = read/write enabled texture storing depth
Depth Buffer / Z buffer = screen space buffer used to store depth of pixels written to check later pixels against for possible discarding.

IIRC it should be 'free' on deferred if in DX11/OpenGl (ES) 3+ / metal / xbone / ps4 as you should be able to use the Z buffer as a texture. On DX9 / OpenGL (ES) 2 / WebGL it depends on driver/card support if it's possible to use the Z buffer, otherwise it's drawn to a texture and the buffer itself is discarded, causing extra draw calls to fill said texture.

Shadowmaps are a different word for depth textures, but from the perspective of the light. Rather unrelated to screenspace depth textures.

I've got no idea about forward rendering, never used it.

Edit: Using a directional light with cascaded shadows <may> force a depth texture to be used.

 

Thanks for the response! Though I am working with forward rendering! Should've mentioned that.

 

Here is the truth
=> DepthTexture never free.

So why doc says it is free when enable shadow mapping or deferred ?
=> Because such algorithm need depth buffer accession.
=> So unity build depth buffer internally.
=> So it is "free" for custom usage. In fact you always cost much more cycles to build depth buffer.

 

Ofcourse, that is what I ment. So, to confirm, in Forward Rendering, assuming I enable shadows on my directional light, I will have access to the depth buffer?

 

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