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UPDATE 3/12/09 - I now declare this FAQ officially defunct. Unfortunately, I have not kept up with the physics processing scene enough to update it. If anyone else would like to post V4, please do so.
UPDATE 5/2/08 - NVIDIA has bought AGEIA and is now porting their physics software to work on GPUs. Therefore, much of the information in this FAQ will soon become irrelevant. Please see this post for more information.
This is V3 of the physics processing FAQ. I would like to give credit to jebo_4jc for writing V2, which was the update to V1.
Q: What is physics processing?
A: The term "physics processing" refers to the use of any piece of hardware to perform calculations related to increasing the amount and realism of physics in games. These physics include active body collisions, motion vectors, ballistic trajectories, soft body deformation, fluid movement and diffusion, and effect of forces, such as gravity, on objects.
Q: Don't all games use physics processing to some degree?
A: Yes, they do. Any game that involves moving objects that interact with the environment uses physics processing. Anything from an FPS to a bowling game needs it to some degree.
Q: So, if games have been doing it for years, why is there so much hype over physics processing now?
A: Until now, all physics processing has been done on the CPU. For this reason, the realism of games' physics has not improved much, as game developers have focused on realistic graphics instead. Now, however, as games near the point of photorealism, that has changed. A wave of movement has started towards better physics. Graphics are no longer enough. Gamers want more realistic physics in addition to more resolution and AA.
Q: How is this new level of realistic physics processing going to be accomplished?
A: Basically, three methods currently exist. One can use a seperate card for physics processing, called a PPU. Alternatively, one can use a GPU or extra CPU cores for physics processing. Each of these methods will be covered in-depth later in the FAQ.
Q: What is the difference between effects physics and gameplay physics?
A: Effects physics processing is only a visual effect, and doesnt affect gameplay in a substantial way. Examples of effects physics enhancements would be larger explosions, debris, shrapnel, and death animations. Gameplay physics would be the ability to use objects in a game world to impact other things in the game world. Like characters being killed by shrapnel from an explosion, or from flying objects as a result of an explosion. Here are some demo videos from NVIDIA and ATI: http://hardforum.com/showthread.php?t=1034977
For more information on effects physics vs gameplay physics, see this interview between [H] and ATI, NVIDIA, Havok, and AGEIA, the main companies behind the new physics hardware.
Q: Who's who in the new physics processing era?
A: It all started when AGEIA, a small company, introduced their idea of the PPU - a seperate card dedicated to physics processing. They soon put their idea to market, and today remain the only company with a physics processing solution that you can actually buy and get limited game support for. Later, ATI and NVIDIA both announced their physics processing solutions - do it on the GPU. NVIDIA, unlike ATI, has now released the chip that will be used for physics processing in the future, although neither company has released the drivers that will enable it as there is no game support at this time. Finally, Havok is the company that everyone knows for creating a widely used CPU physics engine. Right now, Havok is backing ATI and NVIDIA by providing the engine that will be used for GPU physics processing. They are also toying with the third method of advanced physics processing - extra CPU cores.
Q: What are the benefits of better physics processing?
A: There are several advantages including:
Active Bodies: Right now, today's CPUs can only handle around 2,000 active bodies at a time. Accelerated physics processing can increase that number up to 30,000 and beyond. This allows games to use larger enviroments that are more destructible and include more peices that can be realistically moved by collisions with the player or other objects.
Fluids: Today's CPUs are not powerful enough to realistically calculated the movement of a fluid. Accelerated physics processing promises to change that. Unfortunately, the first generation of physics processing devices have not lived up to these expectations. It is hoped that the second generation of advanced physics processing will be able to accurately render realistic fluid movements.
Cloth: Soft bodies, such as cloth, can now deform and ripple in the wind as they would in real life.
Damage: The amount of damage that would be caused after a bullet is fired into a player or building can be accurately calculated. Although not possible with the first generation of physics processors, future products may allow buildings to collapse under their own weight if shot at enough to make them structurally unsound.
At this point, the FAQ will split off into three sections - one for each method of accelerated physics processing. The first solution that will be covered is the PPU.
Q: What is a PPU?
A: PPU stands for physics processing unit. Introduced about a year ago by a company called AGEIA, it is a seperate card that plugs into a PCI slot in your PC and does physics processing using a peice of silicone along with 128MB of RAM located on the card. The card currently costs ~$180, including three PPU-enabled games, and is available at most online retailers. It is manufactured by BFG and ASUS.
Q: How does the PPU perform advanced physics processing?
A: The PPU uses a seperate peice chip containing nearly 300 million transistors that is entirely dedicated to physics processing. This give the PPU an inherent advantage over the other methods - efficiency. Since the hardware is designed to be best at physics calculations, it can do so without requiring massive amounts of transistors to make up for inefficient processing.
Q: Will the PPU be upgraded once every six months, like the GPU?
A: Not every six months, but it will most likely be refreshed regularly as long as it stays in the market. This seems even more probable now that the specifications of NVIDIA's physics solution have been revealed to meet - and exceed - the values of the PPU. While this does not guarantee that NVIDIA's solution will perform better, it may make buyers weary of buying a PPU. To stay in the market, AGEIA is going to have to release an upgraded version of the PPU eventually.
Q: Can it be overclocked?
A: Theoretically, yes, but it remains to be seen whether this can easily be done through software or will require extensive hardware modification.
Q: I don't have a PCI slot open. Will there be a PCI-E version?
A: Yes, there will be a PCI-E version in 2007.
Q: How much of a chance does this method have of surviving in the marketplace?
A: The PPU has one big advantage and several disadvantages over the other methods at this time. The advantage is that the PPU is the only product that is actually working right now and has games available that support it. These games have turned out to be somewhat dissappointing, however, and most gamers should probably wait for the "'real" games like UT2007 and CF:R to be released later before buying a PPU. On the other hand, AGEIA is up against companies much bigger than it, and therefore has an inherent disadvantage trying to sell the PPU. Finally, it looks like NVIDIA's solution is going to be better than the PPU. So, for now, I would recommend against it. When UT2007 is released, if the PPU is still popular, you can buy one.
Next, I will cover the second method of physics processing - using a GPU.
Q: What is this idea of using a GPU for physics?
A: NVIDIA and ATI - the top two manufactuers of GPUs, realized that a graphics processor works in much the same way as a physics processor - using parallel calculations. So, both companies are, along with physics engine creator Havok, promoting the use of a GPU for accelerating physics processing. NVIDIA's product is already out and can either split one GPU for graphics and physics, use one GPU for physics and one for graphics, or use two GPUs for graphics and one for physics. It is anticipated that ATI's solution will work in the same way. The price of a G80 - the GPU required to use NVIDIA's physics solution - is around $450 for a GTS.
Q: I've heard that GPU's can only do effects physics and not gameplay physics. Is this true?
A: No. GPU physics can do both types of physics processing. The reason why Havok stated that GPUs can only do effects physics is because, for now, those are the type of physics that will be implemented most often, since they don't affect the gameplay if a person without the required physics hardware is forced to disable them.
Q: How much of a chance does GPU physics have of staying in the market?
A: GPU physics enjoys several advantages. It is being promoted by the two largest high-end GPU suppliers and a large physics engine creator. Also, the GPU solutions don't require the customer to buy an extra card in a addition to a GPU. This saves slots, case space, and money. Despite the fact that it requires the sacrifice of graphics performance, this one-card solution is bound to appeal to many users. For these reasons, at this point, GPU physics appears to be the method of advanced physics processing with the greatest chance of success.
Finally, I will talk about using extra CPU cores for physics.
Q: Who is promoting the idea of using extra CPU cores for physics?
A: The customers, mainly. Many users just can't understand why they should pay for a hardware physics solution while their four-core CPU just sits with three cores idle, not doing anything useful. Why not just use those cores for physics? Havok appears to be looking into this possiblility, although other than that, there has not been much support for this method of physics processing.
Q: Why the lack of support? It seems like a great idea!
A: It may seem like three extra CPU cores should do great for physics processing, but this is not the case. Physics calculations are massively parallel. CPUs are, for the most part, linear. Therefore, you would need many, many cores to equal the power of a parallel chip such as a PPU or GPU. This, along with the fact that companies want to make money by selling a new product, has resulted in the lack of support for CPU physics.
Q: How much of a chance does this method have of surviving in the market?
A: Although it is not supported now, this method has potential in the future, when the number of cores on a CPU increases. Intel has already stated that they hope to reach 64 cores by 2010. At that point, multi-core physics processing could easily outperform a PPU or GPU. Then perhaps companies will look at multi-core CPU physics more seriously. For now, though, the power needed to do accelerated physics on the CPU just isn't there.
Q: With all of these methods, am I going to need to buy three different things to be able to play all of the games of the future?
A: As always, Microsoft, will come to the rescue here by creating DirectPhysics, a standardized physics API that will probably be included in a future version of DirectX. With all competing solutions using a standard API, one can be assured that, no matter what physics solution they buy, it will work with all of the physics-accelerated games on the market. Ideally, all three solutions will survive, and each customer will be able to buy the one that works best for his situation.
I believe that's it. Mods, do whatever you want with this topic.
UPDATE 5/2/08 - NVIDIA has bought AGEIA and is now porting their physics software to work on GPUs. Therefore, much of the information in this FAQ will soon become irrelevant. Please see this post for more information.
This is V3 of the physics processing FAQ. I would like to give credit to jebo_4jc for writing V2, which was the update to V1.
Q: What is physics processing?
A: The term "physics processing" refers to the use of any piece of hardware to perform calculations related to increasing the amount and realism of physics in games. These physics include active body collisions, motion vectors, ballistic trajectories, soft body deformation, fluid movement and diffusion, and effect of forces, such as gravity, on objects.
Q: Don't all games use physics processing to some degree?
A: Yes, they do. Any game that involves moving objects that interact with the environment uses physics processing. Anything from an FPS to a bowling game needs it to some degree.
Q: So, if games have been doing it for years, why is there so much hype over physics processing now?
A: Until now, all physics processing has been done on the CPU. For this reason, the realism of games' physics has not improved much, as game developers have focused on realistic graphics instead. Now, however, as games near the point of photorealism, that has changed. A wave of movement has started towards better physics. Graphics are no longer enough. Gamers want more realistic physics in addition to more resolution and AA.
Q: How is this new level of realistic physics processing going to be accomplished?
A: Basically, three methods currently exist. One can use a seperate card for physics processing, called a PPU. Alternatively, one can use a GPU or extra CPU cores for physics processing. Each of these methods will be covered in-depth later in the FAQ.
Q: What is the difference between effects physics and gameplay physics?
A: Effects physics processing is only a visual effect, and doesnt affect gameplay in a substantial way. Examples of effects physics enhancements would be larger explosions, debris, shrapnel, and death animations. Gameplay physics would be the ability to use objects in a game world to impact other things in the game world. Like characters being killed by shrapnel from an explosion, or from flying objects as a result of an explosion. Here are some demo videos from NVIDIA and ATI: http://hardforum.com/showthread.php?t=1034977
For more information on effects physics vs gameplay physics, see this interview between [H] and ATI, NVIDIA, Havok, and AGEIA, the main companies behind the new physics hardware.
Q: Who's who in the new physics processing era?
A: It all started when AGEIA, a small company, introduced their idea of the PPU - a seperate card dedicated to physics processing. They soon put their idea to market, and today remain the only company with a physics processing solution that you can actually buy and get limited game support for. Later, ATI and NVIDIA both announced their physics processing solutions - do it on the GPU. NVIDIA, unlike ATI, has now released the chip that will be used for physics processing in the future, although neither company has released the drivers that will enable it as there is no game support at this time. Finally, Havok is the company that everyone knows for creating a widely used CPU physics engine. Right now, Havok is backing ATI and NVIDIA by providing the engine that will be used for GPU physics processing. They are also toying with the third method of advanced physics processing - extra CPU cores.
Q: What are the benefits of better physics processing?
A: There are several advantages including:
Active Bodies: Right now, today's CPUs can only handle around 2,000 active bodies at a time. Accelerated physics processing can increase that number up to 30,000 and beyond. This allows games to use larger enviroments that are more destructible and include more peices that can be realistically moved by collisions with the player or other objects.
Fluids: Today's CPUs are not powerful enough to realistically calculated the movement of a fluid. Accelerated physics processing promises to change that. Unfortunately, the first generation of physics processing devices have not lived up to these expectations. It is hoped that the second generation of advanced physics processing will be able to accurately render realistic fluid movements.
Cloth: Soft bodies, such as cloth, can now deform and ripple in the wind as they would in real life.
Damage: The amount of damage that would be caused after a bullet is fired into a player or building can be accurately calculated. Although not possible with the first generation of physics processors, future products may allow buildings to collapse under their own weight if shot at enough to make them structurally unsound.
At this point, the FAQ will split off into three sections - one for each method of accelerated physics processing. The first solution that will be covered is the PPU.
Q: What is a PPU?
A: PPU stands for physics processing unit. Introduced about a year ago by a company called AGEIA, it is a seperate card that plugs into a PCI slot in your PC and does physics processing using a peice of silicone along with 128MB of RAM located on the card. The card currently costs ~$180, including three PPU-enabled games, and is available at most online retailers. It is manufactured by BFG and ASUS.
Q: How does the PPU perform advanced physics processing?
A: The PPU uses a seperate peice chip containing nearly 300 million transistors that is entirely dedicated to physics processing. This give the PPU an inherent advantage over the other methods - efficiency. Since the hardware is designed to be best at physics calculations, it can do so without requiring massive amounts of transistors to make up for inefficient processing.
Q: Will the PPU be upgraded once every six months, like the GPU?
A: Not every six months, but it will most likely be refreshed regularly as long as it stays in the market. This seems even more probable now that the specifications of NVIDIA's physics solution have been revealed to meet - and exceed - the values of the PPU. While this does not guarantee that NVIDIA's solution will perform better, it may make buyers weary of buying a PPU. To stay in the market, AGEIA is going to have to release an upgraded version of the PPU eventually.
Q: Can it be overclocked?
A: Theoretically, yes, but it remains to be seen whether this can easily be done through software or will require extensive hardware modification.
Q: I don't have a PCI slot open. Will there be a PCI-E version?
A: Yes, there will be a PCI-E version in 2007.
Q: How much of a chance does this method have of surviving in the marketplace?
A: The PPU has one big advantage and several disadvantages over the other methods at this time. The advantage is that the PPU is the only product that is actually working right now and has games available that support it. These games have turned out to be somewhat dissappointing, however, and most gamers should probably wait for the "'real" games like UT2007 and CF:R to be released later before buying a PPU. On the other hand, AGEIA is up against companies much bigger than it, and therefore has an inherent disadvantage trying to sell the PPU. Finally, it looks like NVIDIA's solution is going to be better than the PPU. So, for now, I would recommend against it. When UT2007 is released, if the PPU is still popular, you can buy one.
Next, I will cover the second method of physics processing - using a GPU.
Q: What is this idea of using a GPU for physics?
A: NVIDIA and ATI - the top two manufactuers of GPUs, realized that a graphics processor works in much the same way as a physics processor - using parallel calculations. So, both companies are, along with physics engine creator Havok, promoting the use of a GPU for accelerating physics processing. NVIDIA's product is already out and can either split one GPU for graphics and physics, use one GPU for physics and one for graphics, or use two GPUs for graphics and one for physics. It is anticipated that ATI's solution will work in the same way. The price of a G80 - the GPU required to use NVIDIA's physics solution - is around $450 for a GTS.
Q: I've heard that GPU's can only do effects physics and not gameplay physics. Is this true?
A: No. GPU physics can do both types of physics processing. The reason why Havok stated that GPUs can only do effects physics is because, for now, those are the type of physics that will be implemented most often, since they don't affect the gameplay if a person without the required physics hardware is forced to disable them.
Q: How much of a chance does GPU physics have of staying in the market?
A: GPU physics enjoys several advantages. It is being promoted by the two largest high-end GPU suppliers and a large physics engine creator. Also, the GPU solutions don't require the customer to buy an extra card in a addition to a GPU. This saves slots, case space, and money. Despite the fact that it requires the sacrifice of graphics performance, this one-card solution is bound to appeal to many users. For these reasons, at this point, GPU physics appears to be the method of advanced physics processing with the greatest chance of success.
Finally, I will talk about using extra CPU cores for physics.
Q: Who is promoting the idea of using extra CPU cores for physics?
A: The customers, mainly. Many users just can't understand why they should pay for a hardware physics solution while their four-core CPU just sits with three cores idle, not doing anything useful. Why not just use those cores for physics? Havok appears to be looking into this possiblility, although other than that, there has not been much support for this method of physics processing.
Q: Why the lack of support? It seems like a great idea!
A: It may seem like three extra CPU cores should do great for physics processing, but this is not the case. Physics calculations are massively parallel. CPUs are, for the most part, linear. Therefore, you would need many, many cores to equal the power of a parallel chip such as a PPU or GPU. This, along with the fact that companies want to make money by selling a new product, has resulted in the lack of support for CPU physics.
Q: How much of a chance does this method have of surviving in the market?
A: Although it is not supported now, this method has potential in the future, when the number of cores on a CPU increases. Intel has already stated that they hope to reach 64 cores by 2010. At that point, multi-core physics processing could easily outperform a PPU or GPU. Then perhaps companies will look at multi-core CPU physics more seriously. For now, though, the power needed to do accelerated physics on the CPU just isn't there.
Q: With all of these methods, am I going to need to buy three different things to be able to play all of the games of the future?
A: As always, Microsoft, will come to the rescue here by creating DirectPhysics, a standardized physics API that will probably be included in a future version of DirectX. With all competing solutions using a standard API, one can be assured that, no matter what physics solution they buy, it will work with all of the physics-accelerated games on the market. Ideally, all three solutions will survive, and each customer will be able to buy the one that works best for his situation.
I believe that's it. Mods, do whatever you want with this topic.
