Why is the wireframe rendering so slow compared to solid?

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37 comments, last by iGrfx 4 years, 10 months ago

I wanted to try to overlap wireframe view with the solid view for debugging purposes as I work on the terrain, but just switching to wireframe mode the framerates drop from 900+ when on solid mode to about 70. It's not a heavy scene either, I don't have the poly count but it's probably a couple of thousand. Is this normal? (By the way this is running on debug libraries). Here are some fraps screenshots.

Edit: probably some info is needed here: DX10, win10x64, gtx 970 

 

low.png

high.png

You didn't come into this world. You came out of it, like a wave from the ocean. You are not a stranger here. -Alan Watts

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I have no clue ..... I'm using DX11 and a GTX 660 and I get like 1400 FPS in wire frame with a what seems like a lot more tris than 2K.

 

17 minutes ago, Gnollrunner said:

I have no clue ..... I'm using DX11 and a GTX 660 and I get like 1400 FPS in wire frame with a what seems like a lot more tris than 2K.

Maybe I'm not using the state correctly? All I did was basically flip the D3D10_FILL_SOLID to WIREFRAME without changing any of the other settings? Also I have a gtx 740 not 960, but how are you getting 1400fps on a 660? Is it faster then solid rendering? Do you mind posting a screenshot? 

You didn't come into this world. You came out of it, like a wave from the ocean. You are not a stranger here. -Alan Watts

Ok, so a slight miscalculation, just checked my index buffer it's got about 300,000 indices, so that's roughly 100k tris in the whole scene, I'm guessing the camera sees about 40% of it at any given moment, so that's about 40k tris. So would that be considered a normal framerate for that size of a scene?

 

Edit: here's an image from the mountain top

mount.png

You didn't come into this world. You came out of it, like a wave from the ocean. You are not a stranger here. -Alan Watts

Interesting.

On OpenGL the framerate drops as well by ~50% when switching from triangles to lines, no other state change.

Could it have something to do with the faces ? I cull half the faces in triangle mode ...

1 minute ago, Green_Baron said:

Interesting.

On OpenGL the framerate drops as well by ~50% when switching from triangles to lines, no other state change.

Could it have something to do with the faces ? I cull half the faces in triangle mode ...

I think the back faces are still culled, however with wireframe there is no longer any hidden surface removal which adds to the poly count, but still it's a significant drop even with that

You didn't come into this world. You came out of it, like a wave from the ocean. You are not a stranger here. -Alan Watts

more triangles are passing the depth test and being sent through. yes.

10 minutes ago, GoliathForge said:

more triangles are passing the depth test and being sent through. yes.

Yes, but shouldn't the gfx card be able to handle millions of tris/second? My scene has 100,000 at max, and even then they're never drawn all at once.

You didn't come into this world. You came out of it, like a wave from the ocean. You are not a stranger here. -Alan Watts

how is that metric really? Is it 1000k(s) tris/sec all visible at once or is it that many tris going through the pipe and well, our culling hardware is great...I actually wondered about that. openGL has always given me slightly less performance than chart. (but I actually prefer)

1 minute ago, GoliathForge said:

how is that metric really? Is it 1000k(s) tris/sec all visible at once or is it that many tris going through the pipe and well, our culling hardware is great...I actually wondered about that. openGL has always given me slightly less performance than chart. (but I actually prefer)

No, I have 100,000 triangles going through the pipe but I'm estimating only about half of them are visible at any given moment. It must be something with the settings though or some other issue because if I let's say face the camera away from the mountains just towards empty space the frame rate goes up to about 250 fps. Which is still 1/4 of what it is when looking at the mountains while textured, so it makes no sense to me.

You didn't come into this world. You came out of it, like a wave from the ocean. You are not a stranger here. -Alan Watts

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