InstancedRendering

This originally started out as an attempt to try out instanced rendering. It now includes an OpenCL wind simulation.

The program is written in C++/Qt. OpenGL and OpenCL are both used, but some of the OpenCL code is Apple-specific (guarded by #ifdef __APPLE__). Fortunately, these instances are completely isolated to two files: include_opencl.h and myclwrapper.cpp.

1. The cl_interface/include_opencl.h header does a platform-specific OpenCL include. For Apple, this is <OpenCL/opencl.h>, and for other systems it might be different. By default, if __APPLE__ isn't defined, I include <cl.h>.
2. Change makeCLGLContext() in MyCLWrapper.

Controls

Press F to toggle the force. The quad in the upper-right corner displays the wind velocities. The grass reacts to the wind.

Features

• 128x128 grass blades are drawn with a glDrawArraysInstanced() call.
• OpenCL code approximates the Navier-Stokes equations for an incompressible fluid.
• The grass waves in response to the wind.

Specifics

A small script creates the grass blade model. Per-instance data is stored in special per-instance buffers. I use glVertexAttribDivisor() and glDrawArraysInstanced() to achieve this.

To simulate wind, I use the Navier-Stokes approximation described here. My code for this is currently quite messy.