Spy Game Blood Stone’s water effects
Martin McEachern
November 19, 2010

Spy Game Blood Stone’s water effects

When the digital 007 accepts his latest interactive mission, he takes to the land and water to catch the bad guys. See how the artists at Bizarre Creations generated the water’s wake in the Athens scenes.

In the newly released game James Bond 007: Blood Stone, the superspy takes to the water during some intense chase scenes. To this end, the CG speedboats, Ekranoplans, yachts, hovercrafts all called for specific waves and wakes, along with a flood of water effects, like sea spray and whitecaps. The faster watercraft, like the speedboats, cast a blinding spray on the characters and the camera. To handle these water effects, Bizarre Creations developed two types of wakes: one for the speedboats and hovercraft, and the second for the yacht featured in the Athens scenes.

The first wake type, for the speedboats in the pre-credit chase, used a mixture of quad and soft rotating sprites. “The quad particles were used to create the wake part of the effect. Orientated to the Y axis, the particles were then set to scale uniformly, while the alpha was made to fade out over the life of the particle,” explains technical effects artist Nigel Middleman. “We used several emitters within this part of the effect, creating the different intensities within the water wake. For instance, we had the larger particles that were active for longer, but were more transparent. This simulated the outer part of the wake, while smaller particles had their intensity and transparency set slightly higher, thus simulating the foam within the wake.”

The second part of the effect is the spray that gets thrown up into the air. For this, the crew used rotating sprites, which again scaled and faded out. They then used several emitters to control the size and density of the particles to get a greater sense of volume within the effect. For both the effects that comprise the water spray and wake effect, the artists used a distance-based emission rate, rather than emitting the particles over a time-based value. “This created a much better looking trail effect compared to emitting them over time, though requiring a lot more particles to create the density we wanted within the effect,” says Middleman.

To intensify the visceral impact of the speed, the artists borrowed a cinematic trick—water drops sprayed onto the cameras lens. A full-screen effect, the droplets comprised a small normal-map texture that was then rendered onto the screen, with a color buffer creating the refraction effect. “The speed of the camera then determined how fast the water drops moved to the edge of the screen,” explains Middleman. “The rate that the water drops were applied to the camera lens was based on a spherical bounding area. The origin was located where the effect was attached to the speedboat; this allowed us to create the effect as the player got closer to a speedboat.” A boat that was ahead of the player would gradually fill the screen with more spray.

The second wake, which trails the cruise ships in the pre-credit harbor, was forged through a mixture of meshes comprising animated shaders and particles. “For the wake element of the effect, we used two meshes that stretched the length of the hull. The first mesh was a constant width. With a simple scrolling UV shader applied with the U value, it was animated to give the impression of the moving water along the hull. The vertices of the mesh located at the back of the boat were then faded out using vertex alpha value. The texture also had an alpha channel that furnished the foamy water at the edges,” summarizes Middleman.

The second mesh was slightly shorter than the ship’s hull, but tapered outward as it approached the stern. This mesh simulated the small waves that emanated from the hull as the ship moved forward. For this part of the effect, the team used a scrolling UV shader again, but this version supported two UV sets, each with its own scrolling speed value. “This allowed us to create the effect of different size waves moving at different speeds, while still using the same texture,” says Middleman. “We then painted the alpha values onto the vertices of the mesh to fade off the effect at the rear and sides of the mesh.”

Finishing the effect, the artists used simple particles to create the spray at the front of the hull and the wash at the rear. A point emitter cast the front spray with soft, rotating particles, which used the Z-depth buffer to fade off the edges of the particles as they passed through the mesh of the ship’s hull. The rear wake required the same method as the speed boats, employing quad particles of different sizes that were constrained to—and also rotated slightly within—the Y axis. However, instead of using a point emitter, the artists used a sphere emitter with no height value applied. This afforded a wider spread of particles, consistent with the wake of a large ship.

“This method allowed us to create the proper visual density within the effect, without having to resort to too many large particles,” says Middleman.

For an in-depth look at the cutting-edge CG required to make this game, see “Like a Rolling (Blood) Stone” in the November issue of Computer Graphics World.

Martin McEachern is an award-winning journalist and contributing writer for Computer Graphics World. He can be reached at martinmceachern@hotmail.com