434c226e8a
cmgen mirrors environment maps by default so that the reflection map appears un-mirrored. IBLPrefilter didn't do that. EquirectangularToCubemap now takes a Config parameter that allows to specify the mirroring, which is enabled by default. FIXES=[320856413]
IBL Prefilter
This library can be used to generate the reflections texture used by filament's IndirectLight
class. It is similar to the cmgen tool except that all computations are performed on the GPU and
are therefore significantly faster. cmgen however offers more functionalities.
IBL Prefilter is designed entirely as a client of filament, that is, it only uses filament
public APIs.
Library and headers
The library is called libfilament-iblprefilter.a and its public headers can be found in
<filament-iblprefilter/*.h>.
Performance
Expect a total processing time of about 100ms to 300ms for a 5-levels 256 x 256 cubemap with 1024 samples.
Example
#include <filament/Engine.h>
#include <filament-iblprefilter/IBLPrefilterContext.h>
using namespace filament;
Engine* engine = Engine::create();
// create an IBLPrefilterContext, keep it around if several cubemap will be processed.
IBLPrefilterContext context(engine);
// create the specular (reflections) filter. This operation generates the kernel, so it's important
// to keep it around if it will be reused for several cubemaps.
IBLPrefilterContext::SpecularFilter filter(context);
// launch the heaver computation. Expect 100-100ms on the GPU.
Texture* texture = filter(environment_cubemap);
IndirectLight* indirectLight = IndirectLight::Builder()
.reflections(texture)
.build(engine);