When given the chance recently to present technical director of Evolution Studios Scott Kirkland with some questions, we took the opportunity to ask about the development of Motorstorm and where he sees future development efforts on the Playstation 3 as heading.
B3D: Earlier this year you were quoted in the press release
announcing version 4.5 of Havok's SDK; how closely have Evolution and
Havok worked together throughout the development of Motorstorm, and
to what extent has Havok formed a foundation for Motorstorm's
physics-based gameplay?
Scott Kirkland: Since adopting
Havok’s physics middleware, Evolution and Havok have worked in very
close collaboration. While Havok’s engineers concentrated on
refining their core functionality and tools, our internal physics
programmers were able to focus on MotorStorm’s application of
physics... creating the game’s compelling vehicle dynamics systems,
environmental interaction, and spectacular destruction.
B3D: In your mind, what would you say has been the most
significant in-house tool development at Evolution to have come out
of the Motorstorm project?
Scott Kirkland: We put a lot
of effort into the development of real time remote (socket API)
debugging tools. These included screen and AV capture, memory
allocation tracking and hierarchical performance analysis of
instrumented code. This work will provide the foundation for a much
broader suite of tools to collect valuable statistics and allow our
artists to interactively configure aspects of future products.
B3D: Will the next project out of Evolution continue to
build upon the Motorstorm engine, or is the present expectation that
work for a new title will commence with a clean slate from the engine
side?
Scott Kirkland: During the development of
MotorStorm our team learned a great deal about PlayStation3
exploitation and production process refinement. While much of this
knowledge fed directly into our systems, some items had to be put on
hold due to their more radical nature. As we progress, these areas
will be subjected to some serious re-factoring to provide increased
performance both at runtime and during development.
SPU usage
is a good example. The progressive development of corresponding
debugging and profiling tools made thorough exploitation of this
powerful resource quite challenging for the less technically biased
members of the team. In the aftermath of MotorStorm, with mature
tools at our disposal, we’ve been developing mechanisms to make the
PPU and SPU’s power and parallelism far more accessible to our
entire team, re-thinking data organization and algorithms in the
process. MotorStorm only uses between 15 and 20 percent of available
SPU resource, so we’re aiming to achieve a 5 fold increase in SPU
performance, which should allow us to do some awesome stuff!
B3D:
Cell's ability to assist RSX in rendering operations has been a topic
of much debate and speculation of late. Was Cell used in
Motorstorm to perform any lighting, vertex, or other transform
work?
Scott Kirkland: We don’t use the Cell’s SPUs
in this way at the moment. All of our lighting and
transformation work is done in the RSX’s pixel and vertex shaders.
Our SPU exploiting systems consist of:
i) Havok physics.
ii) Determination of object visibility.
iii) Concatenation of hierarchies.
iv) Billboard object culling and vertex buffer creation.
v) Updating of particles and vertex buffer creation.
vi) Updating of vehicle dynamics.
vii) Updating of vehicle suspension constraints.
viii) Audio (MultiStream).
ix) Video decoding.
B3D: Were Evolution's thoughts that the application of Cell towards such tasks might go too far in removing SPEs from being available for work on AI, physics, and other gameplay-related code?
Scott Kirkland: Cell’s SPUs provide a huge amount of processing power. Early adopters tended to bias usage towards either RSX or PPU support (we fall into the latter category). I’m confident that over the coming months, exploitation of this resource will become far more balanced.
B3D: Further to that, do you believe that as the generation progresses, cooperative rendering techniques will become a larger part of what grows to define baseline PS3 rendering methods, or are your thoughts that such efforts will play out more or less in niche areas?
Scott Kirkland: If by “cooperative rendering†you’re referring to SPUs supporting the RSX, I strongly believe that this approach will become far more widespread. In addition to reducing the vertex load on the RSX through the use of culling and vertex pre-processing, this approach also provides an efficient mechanism to introduce procedural geometry.
Historically, CPUs have provided course grain scene culling using view frustums, occlusion planes, portal visibility and BSP-trees with GPUs left to perform fine grain rejection using guard band clipping, occlusion and backface culling. While such features improve fragment performance, they don’t reduce vertex processing overhead.
The leap in performance provided by Cell gives us the bandwidth to significantly reduce RSX time spent processing vertices that don’t contribute to the final scene. The favoured approach is to use SPUs to generate minimal scene/instance specific index and vertex buffers from compressed data.
B3D: Many thanks for your answers thus far Scott - one last
question before we go. Sony Worldwide Studios has seemed very
involved in assisting the efforts of closely-affiliated developers,
and Phil Harrison in particular has seemed very excited about the
title. To what extent would you say Sony WWS provided a hand in
aiding Evolution with the development of Motorstorm?
Scott
Kirkland: We have had a close relationship with Sony ever since
our early days as the PS2 World Rally Championship developer. Sony
trusted us with the WRC license, even though we were just a small
team with no console experience, just a big sack of talent and
enthusiasm. Phil has often visited our studio and knows most of us
personally – we certainly never felt neglected by SCEE and their
tech guys were always willing to answer our queries. That said, it is
the guys at Studio Liverpool who we work most closely with, and they
are top guys.
