The Bureau: XCOM Declassified PhysX-Interview English
Ewan Croft, Lead Artist for the high end PC, answered our questions regarding GPU PhysX implementation in The Bureau: XCOM Declassified. Thanks for the answers.
PCGH: You implemented GPU accelerated physics into The Bureau: XCOM Declassified. Is it just an optical, gimmicky feature or is it implemented into the gameplay, let's say for destructible objects?
Ewan Croft: The GPU accelerated physics in the Bureau are mostly aimed at augmenting an already high degree of visual fidelity rather than altering gameplay. One question we asked ourselves early on was "how much do we change the core experience with PhysX/APEX features?" We decided that a consistent gameplay experience between all platforms was very important so while high-end PC users will enjoy additional physics features such as reactive GPU particles, more reactive actors and tearable cloth, gameplay is consistent for all users.
PCGH: What modules of the PhysX library are used and what effects are rendered with them?
Ewan Croft: We implemented a selection of PhysX and APEX features including turbulence grids and jets, GPU particles, and tearable cloth (APEX and PhysX cloth for different applications). An example of how we used these features is the drop-pod effects. In the Bureau, enemies can be spawned through drop pods sent from the mothership. The enemies initially "warp" in so they are invisible as they materialize. However, with the APEX features enabled, players can see the turbulence created in the particle field by the enemy as they move to cover. This is not only a visually striking effect but informs the player where the bad guys are going before they have warped in completely.
PCGH: Can these effects be specifically controlled, for example can a single effect be turned off, if the user doesn't like it or hasn't a strong enough PC to calculate it, or are there going to be preset options like "PhysX high" and "PhysX low"?
Ewan Croft: Absolutely - while our PhysX additions are geared towards high-end PC users with formidable Nvidia GPUs, one of our mottos from the start was "do no harm". Again, we were very conscientious about ensuring that the core gameplay experience was consistent across all platforms. Even the lowest-end PCs should be able to experience The Bureau with the higher end features turned down or off completely without detrimentally affecting gameplay. This is true for Nvidia features as well our own proprietary improvements such as screen-space reflections.
PCGH: Will gamers still be able to activate PhysX, if they don't own an Nvidia-card and their CPU is strong enough? Or will only Nvidia-users be able to activate PhysX?
Ewan Croft: The Bureau will detect what kind of GPU the user is running and will enable the appropriate Nvidia features if a capable GPU is found. If not, features that will run too slowly on other manufacturer's GPUs or the CPU are disabled by default. However, users can toggle these features on and off to see which run just fine and which cause performance issues. Many of the Nvidia features do run on non-Nvidia GPUs albeit not as efficiently. Some features will be passed over to the CPU if no feature-compatible GPU is detected but even very capable CPUs will struggle with the higher end features such as tens of thousands of reactive GPU particles.