Comments on: Practical Direct3D Programming

By: SteelGolem

SteelGolem — Mon, 05 Nov 2007 23:50:05 +0000

i wanted to bring up a point i think might have been missed – his terrain ISN’T going to be static at all. doesn’t one of the requirements of building an index array or triangle buffer supposed to be that it doesn’t change? a major part of planitia (much like it was in populous) was the ability to shift the land up and down to shape it for your people. i think that means he needs to avoid as much vram buffering as he can. now i’m a newb and i’ve just learned how to use the vert buffs, so please correct me if i’m wrong on this.

By: Viridian

Viridian — Wed, 10 Oct 2007 19:10:07 +0000

No, DirectX’s sprite library pretty much took the place of SDL. If I had used OpenGL I probably would have continued to use SDL as well, since they integrate, but I couldn’t do that with Direct3D. So SDL is out of my framework now.

By: Matt

Matt — Wed, 10 Oct 2007 09:43:18 +0000

Viridian, maybe you answered this before but I was wondering if you were using SDL for anything in Planitia or just DirectX?

By: Viridian

Viridian — Tue, 09 Oct 2007 01:24:18 +0000

Woohoo! Graphics programmer slapfight in my comments!

By: Ryan

Ryan — Mon, 08 Oct 2007 23:27:11 +0000

I totally agree with your recommendation of multitexturing, BTW. It’s a definite win, especially for low-end harware where verts are expensive… but so is index culling

By: Ryan

Ryan — Mon, 08 Oct 2007 23:15:58 +0000

One more sad reality must be faced in PC land: the most common 3D accelerators today are Intel’s integrated variety. They outsell both AMD and Nvidia!

Even though they support pixel shaders, these most-common GPUs don’t accelerate vertex operations at all. Every single vertex transformation is done on the CPU!

So if you’re optimizing for low-end PCs, limiting your vertex count remains the single most important thing to do.

If you’re aiming for dedicated gamers, then vertex count is less likely to be a bottleneck. But if you’re aiming for casual / low-end gamers, the situation is different.

By: Ian

Ian — Mon, 08 Oct 2007 19:54:35 +0000

According to the post the world of Planitia is 64×64 tiles of four triangles each. That’s 16k triangles which is easily drawn without any form of culling. The problem is that the terrain needs to be drawn muliple times for each terrain type. Instead of culling tiles to the camera he could have gone the multitexture route.

My original point still stands, relative to changing buffers and some expensive renderstates, triangles are cheap. That’s all I’m trying to say.

To break out the broken record, it doesn’t really matter. He has the performance he wants.

By: Ryan

Ryan — Mon, 08 Oct 2007 04:30:44 +0000

Yeah, but I don’t think we’re talking about a lot of bus traffic here…. those Indices are just two bytes each.

By: sol_hsa

sol_hsa — Sat, 06 Oct 2007 10:57:47 +0000

Well, it WAS about avoiding buffer locks and state changes, now it’s about minimizing bus traffic and optimizing shaders.. =)

By: Ryan

Ryan — Fri, 05 Oct 2007 20:40:06 +0000

I think you guys are missing something: Viridian isn’t sending geometry to the card evrey frame. He’s only culling his index buffer. I’m pretty sure his verts are static.

And I wouldn’t expect culling to be a per-frame expense in a game like planitia anyway, because the camera isn’t usually moving. You don’t need to cull when your camera’s holding still