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      <page pageid="19" ns="0" title="Spore Prototype Gaslight">
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          <rev xml:space="preserve">===='''Overview'''====

Gaslight simulates a process known as stochastic, [http://en.wikipedia.org/wiki/SSPSF_model self-propagating star formation], or SSPSF.  

The SSPSF model suggests that when stars form in nursery nebulae, the solar winds they generate compress the interstellar medium causing nearby regions of the nebula to become more dense, thereby speeding up gravitational collapse and promoting the formation of more stars, which in turn compress the interstellar medium further and promote the formation of more stars.

===Gas Simulation===

Gaslight simulates SSPSF by creating a field of cells each with a mass value, representing the amount of matter in the cell, and a temperature value.  

To simulate the flow of matter between cells, I apply a pressure differential formula based on the tried-and-true ideal gas law which we all learned in high school chemistry.  The formula for the ideal gas law is PV = nRT, where P is pressure, V is volume, n is the number of molecules (proportional to mass), T is temperature and R is a constant.  

In Gaslight, V is a constant, as each cell is the same size, so we can define R' as R/V and rewrite: P = nR'T.  This gives us the net pressure in a cell given mass and temperature.  During simulation, each cell's pressure is compared with its neighbors and flow vectors based on the pressure differential are calculated for each neighbor.  Mass is moved from one cell to another using these vectors and the temperature of the newly introduced gas is combined with the temperature of its new home cell, and so is heat propagated through the system as well.

===Star Formation===

As the mass value of a cell increases, the probability of generating a star goes up.  

Stars are represented by free roaming objects running a simplified version of the gravitational simulator developed for [[Spore Prototype Particle Man|Particle Man]].  This gives the stars the opportunity to drift out of their nursery nebulae.

Star lifetimes are inversely proportional to mass.  Larger stars emit more heat and die younger.  The problem with this is that red dwarfs, which are very small, live a long, long time.  To prevent the system from becoming filled with red dwarf stars, I added a red dwarf culling feature that limits the population of small stars.

When most stars die, they simply blink out.  But massive stars go nova, releasing large amounts of energy into the system.

--

Return to [[Spore Prototypes]]</rev>
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      <page pageid="18" ns="0" title="Spore Prototypes">
        <revisions>
          <rev xml:space="preserve">===='''Background'''====

In 2000, I was working at Maxis Studios when [http://en.wikipedia.org/wiki/Will_Wright Will Wright] asked me to begin developing a series of prototypes for a new game idea he had about evolution and the spread of life throughout the galaxy.  I had spent the previous couple of years developing climate models for terraforming Mars and much of that work would end up being applied to Spore.

Many years later, after the release of Spore, Electronic Arts made some of these prototypes [http://www.spore.com/comm/prototypes available for download].

The pages below describe each of the prototypes I worked on.

===Gaslight===

[[Spore Prototype Gaslight|Gaslight]] is a stellar evolution system which simulates the process of [http://en.wikipedia.org/wiki/SSPSF_model stochastic, self-propagating star formation.]

===Particle Man===

[[Spore Prototype Particle Man|Particle Man]] is a multi-body gravity simulation.

===Water Boy===

[[Spore Prototype Water Boy|Water Boy]] is heightfield-based large-body water simulation.

===BIOME===

[[Spore Prototype BIOME|BIOME]] is a programmable system for creating non-directional cellular automata.  The BIOME language is based on chemical stoichiometry.

===Crowd===

[[Spore Prototype Crowd|Crowd]] is a traffic and flocking crowd simulation originally developed for SimCity and later applied to the city management portion of Spore.

===Tidepool===

[[Spore Prototype Tidepool|Tide Pool]] is an early gameplay prototype which combines BIOME-based cellular automata, Water Boy-based fluid simulation and Crowd-based flocking with a simple flight model.

[[Spore Prototype SPUG|SPUG]] is a later stage gameplay prototype where we see the beginnings of the Spore Creature Game beginning to emerge.

[[Spore Prototype Gonzago|Gonzago]] was the last prototype developed for Spore where we see the project take its final shape.</rev>
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