Quote:Original post by Promit So HL2 is not using true shadow mapping ever? Or is it only on the cheaper paths where they use projected texture shadows?
I wonder about that, too. To me it occured as if the shadows were pretty much correct (e.g. including self-shadowing). In my settings all options including shadows and shader detail are maxed out (got a semi-decent fully DX9 compatible Radeon). I *guess* the artifacts stem from the sub-optimal rendering path, but maybe I just didn't look too closely at the shadows [wink].
Quote:Original post by Hardguy I think it uses something called texture shadows that is used in alot of games for character shadows. Basically all objects have a texture that has a shadow rendered onto it and that then is projected onto the world. This technique is used in Ogre for example. It has some limitations like no self-shadowing and (at least in Ogre) shadowscasting objects can't recieve shadows.
Not 100% sure about this though so please correct me if I am wrong.
I'm not certain... The shadows here, in Ogre's shadow demo, are stencil shadows, not shadowmaps.
Ogre supports additive stencil (like Doom3, self-shadowing and multi-light accurate), modulative stencil (Neverwinter Nights, self-shadowing but not multi-light accurate) and fixed-function projective texture shadows (no self-shadowing, not multilight accurate). Each has it's own benefits and trade offs.
The reason for not using shadow maps out of the box is that they require shaders to be applicable to all hardware / APIs. For example, on GL there is a shadowmap extension, but on DirectX there is no non-shader standard; merely the 'magic' nVidia depth texture support and nothing on ATI without shaders. Due to time constraints we supported the biggest user base by supporting fixed function with the option for the user to supply custom shadow caster / receiver shaders if more advanced effects were required (with the inherent minimum card requirements).
I'm using a Radeon 9700, and my settings are on high for everything. It actually occured to me that the metal sheets I used to check might not cast very sophisticated shadows so I tried using the airboat placed on top of the car, but the artifact was still there. I suppose in-game this is less noticable, because 2 shadow casting objects rarely get into a position where their shadows are cast onto the same surface. Still, it seams like a bit of a cheap effect, which makes me wonder whether it is due to my graphics card. If anyone is running HL2 on something more substantial than a 9700 they could clarify...
It happens on my Geforce 6800 (In half life 2), and it happened in their demonstration before they released the game, it's a limitation of the engine I think.
