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https://github.com/openmm/openmm
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9a0db72533
* Implemented CustomCPPForceImpl * Documentation for CustomCPPForceImpl * Attempt at fixing Windows compilation error * Improved documentation
53 lines
2.1 KiB
ReStructuredText
53 lines
2.1 KiB
ReStructuredText
.. role:: code
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.. raw:: html
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<style> .code {font-family:monospace;} </style>
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<style> .caption {text-align:center;} </style>
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.. highlight:: c++
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.. _customcppforceimpl:
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Platform-Independent Code with CustomCPPForceImpl
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#################################################
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In most cases, Forces are written with platform-specific code that runs as
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efficiently as possible on the available hardware. There are some situations
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where that is unnecessarily complicated. For example, you might write a plugin
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that interfaces to an external library through its own public API. Because all
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expensive calculations are done by the external library, there is little
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opportunity for any kind of platform-specific optimization. All you can do is
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copy positions over to the external library and copy forces back, hopefully in
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a way that is not too inefficient, and preferably with as little code as
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possible. CustomCPPForceImpl is a tool for doing that.
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To use it, you write your Force subclass in the usual way, providing whatever
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API is appropriate for it. Then for the corresponding ForceImpl, simply
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subclass CustomCPPForceImpl and override :code:`computeForce()` to perform the
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calculation using platform-independent C++ code. Nothing more is required. It
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will automatically work on all platforms. You do not need to write any GPU
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code, provide a Kernel or KernelFactory, define registration functions, or even
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create plugin libraries to be loaded dynamically. The single library containing
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the Force and ForceImpl is all you need.
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Here is an example of what the code to implement your ForceImpl might look like.
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::
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class ExampleForceImpl : public CustomCPPForceImpl {
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public:
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ExampleForceImpl(const ExampleForce& owner) : CustomCPPForceImpl(owner), owner(owner) {
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}
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double computeForce(ContextImpl& context, const vector<Vec3>& positions, vector<Vec3>& forces) {
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// Compute the forces and energy here. Store the forces into the
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// vector and return the energy.
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}
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const ExampleForce& getOwner() const {
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return owner;
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}
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private:
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const ExampleForce& owner;
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};
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