Thursday, December 15, 2011

QuickStart Game Engine v0.25 Preview: Buoyancy/Density Physics

I'm currently working on v0.25 of the QuickStart Game Engine, which will include a handful of performance enhancements, but most of the work has gone into a new component called WaterVolumePhysicsComponent. This component lets you describe a volumetric region in which water physics will be applied to any dynamic physics body, this means that water will now apply drag to anything within it, it will apply a weight to objects as they leave the water (because they're still "wet"), and it will take into account the density differences between the water and the physics body, allowing less dense entities to float, and denser entities to sink. The density differences between the body and water will also determine if the entity just barely sits near the top of the water, or if it's incredibly light it will float almost entirely on top of the water.

In previous versions of the engine there has been a yellow sphere that could be fired by pressing spacebar, in the new demo there will be two new spheres, a blue one fired by pressing Left Ctrl, and a red one fired by pressing Left Shift. The blue sphere will be extremely light, letting it rise very quickly out of the water and float almost entirely on top of the water, the yellow sphere will be medium density which is slightly less dense than water, letting it float to the top but not sit as high above the water as the blue sphere, and the red sphere will be very heavy and dense, letting it sink to the bottom of the water.

Density is really all that matters in terms of buoyancy in the water, but it also affects the amount of force and momentum an object has; All 3 spheres are the same size, but different densities, so each sphere weighs much differently than another. If you fire a blue sphere at one of the wooden crates in the demo, it doesn't have enough weight to move the crate almost at all, but the yellow sphere can give it a small nudge because it's a higher weight, and the red sphere can knock the crates around pretty good because they're much heavier than the crates. It is fun to fire the different spheres at things and watch how they act differently in the water.

I expect version 0.25 to be released in the next week or two.

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