short README for examples/fluid

examples/fluid/README.md

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+A Stable Fluid Simulation
+=========================
+
+This is an implementation of the fluid simulation described in the paper
+"Real-time Fluid Dynamics for Games" (Jos Stam, GDC 2003).
+
+
+Usage
+-----
+
+Running the program opens a window which displays the current state of the
+simulation.
+
+Execute with the flag "--help" to display a complete list of command-line
+options and runtime controls.
+
+To interact within the simulation window:
+
+  click                 add particles to the simulation
+  shift-click-drag      introduce forces, proportional to the speed of motion
+  r                     reset the simulation to the initial state
+  d                     toggle display of the density (particle) field
+  v                     toggle display of velocity field lines
+
+
+Notes
+-----
+
+The animation package does not drop frames that arrive late, so if you request a
+framerate that is too high, the frames will back up and the program slowly grind
+to a halt. You can test the capability of your hardware, instead of running the
+simulation proper, by executing with the flag "--benchmark". Select a
+"--framerate" and simulation "--width" & "--height" as appropriate.
+
+When running in the CUDA backend, it will take several seconds before all
+kernels are compiled and the simulation is ready.
+
+It is often nice to start with some initial data, rather than a blank screen.
+You can use the flags "--bmp-density" and/or "--bmp-velocity" to introduce
+initial conditions by reading from a bitmap image file. Try using one of the
+images located in `data/images` as an initial density source.
+