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IBLPrefilter can now generate the irradiance texture
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@pixelflinger
pixelflinger committed May 23, 2023
1 parent 153dc08 commit a976337
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Showing 4 changed files with 375 additions and 34 deletions.
107 changes: 102 additions & 5 deletions libs/iblprefilter/include/filament-iblprefilter/IBLPrefilterContext.h
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Original file line number Diff line number Diff line change
Expand Up @@ -58,6 +58,10 @@ class Texture;
class UTILS_PUBLIC IBLPrefilterContext {
public:

enum class Kernel : uint8_t {
D_GGX, // Trowbridge-reitz distribution
};

/**
* Creates an IBLPrefilter context.
* @param engine filament engine to use
Expand Down Expand Up @@ -109,7 +113,7 @@ class UTILS_PUBLIC IBLPrefilterContext {
* - Must be allocated with all mip levels.
* - Must be SAMPLEABLE
* @param outCubemap Output cubemap. If null the texture is automatically created
* with default parameters (size of 256 with 5 levels).
* with default parameters (size of 256 with 9 levels).
* - Must be a cubemap
* - Must have SAMPLEABLE and COLOR_ATTACHMENT usage bits
* @return returns outCubemap
Expand All @@ -123,6 +127,100 @@ class UTILS_PUBLIC IBLPrefilterContext {
filament::Material* mEquirectMaterial = nullptr;
};

/**
* IrradianceFilter is a GPU based implementation of the diffuse probe pre-integration filter.
* An instance of IrradianceFilter is needed per filter configuration. A filter configuration
* contains the filter's kernel and sample count.
*/
class IrradianceFilter {
public:
using Kernel = Kernel;

/**
* Filter configuration.
*/
struct Config {
uint16_t sampleCount = 1024u; //!< filter sample count (max 2048)
Kernel kernel = Kernel::D_GGX; //!< filter kernel
};

/**
* Filtering options for the current environment.
*/
struct Options {
float hdrLinear = 1024.0f; //!< no HDR compression up to this value
float hdrMax = 16384.0f; //!< HDR compression between hdrLinear and hdrMax
float lodOffset = 2.0f; //!< Good values are 2.0 or 3.0. Higher values help with heavily HDR inputs.
bool generateMipmap = true; //!< set to false if the input environment map already has mipmaps
};

/**
* Creates a IrradianceFilter processor.
* @param context IBLPrefilterContext to use
* @param config Configuration of the filter
*/
IrradianceFilter(IBLPrefilterContext& context, Config config);

/**
* Creates a filter with the default configuration.
* @param context IBLPrefilterContext to use
*/
explicit IrradianceFilter(IBLPrefilterContext& context);

/**
* Destroys all GPU resources created during initialization.
*/
~IrradianceFilter() noexcept;

IrradianceFilter(IrradianceFilter const&) = delete;
IrradianceFilter& operator=(IrradianceFilter const&) = delete;
IrradianceFilter(IrradianceFilter&& rhs) noexcept;
IrradianceFilter& operator=(IrradianceFilter&& rhs) noexcept;

/**
* Generates an irradiance cubemap. Mipmaps are not generated even if present.
* @param options Options for this environment
* @param environmentCubemap Environment cubemap (input). Can't be null.
* This cubemap must be SAMPLEABLE and must have all its
* levels allocated. If Options.generateMipmap is true,
* the mipmap levels will be overwritten, otherwise
* it is assumed that all levels are correctly initialized.
* @param outIrradianceTexture Output irradiance texture or, if null, it is
* automatically created with some default parameters.
* outIrradianceTexture must be a cubemap, it must have
* at least COLOR_ATTACHMENT and SAMPLEABLE usages.
*
* @return returns outIrradianceTexture
*/
filament::Texture* operator()(Options options,
filament::Texture const* environmentCubemap,
filament::Texture* outIrradianceTexture = nullptr);

/**
* Generates a prefiltered cubemap.
* @param environmentCubemap Environment cubemap (input). Can't be null.
* This cubemap must be SAMPLEABLE and must have all its
* levels allocated. If Options.generateMipmap is true,
* the mipmap levels will be overwritten, otherwise
* it is assumed that all levels are correctly initialized.
* @param outIrradianceTexture Output irradiance texture or, if null, it is
* automatically created with some default parameters.
* outIrradianceTexture must be a cubemap, it must have
* at least COLOR_ATTACHMENT and SAMPLEABLE usages.
*
* @return returns outReflectionsTexture
*/
filament::Texture* operator()(
filament::Texture const* environmentCubemap,
filament::Texture* outIrradianceTexture = nullptr);

private:
filament::Texture* createIrradianceTexture();
IBLPrefilterContext& mContext;
filament::Material* mKernelMaterial = nullptr;
filament::Texture* mKernelTexture = nullptr;
uint32_t mSampleCount = 0u;
};

/**
* SpecularFilter is a GPU based implementation of the specular probe pre-integration filter.
Expand All @@ -131,9 +229,7 @@ class UTILS_PUBLIC IBLPrefilterContext {
*/
class SpecularFilter {
public:
enum class Kernel : uint8_t {
D_GGX, // Trowbridge-reitz distribution
};
using Kernel = Kernel;

/**
* Filter configuration.
Expand All @@ -151,7 +247,7 @@ class UTILS_PUBLIC IBLPrefilterContext {
float hdrLinear = 1024.0f; //!< no HDR compression up to this value
float hdrMax = 16384.0f; //!< HDR compression between hdrLinear and hdrMax
float lodOffset = 1.0f; //!< Good values are 1.0 or 2.0. Higher values help with heavily HDR inputs.
bool generateMipmap = true; //!< set to false if the environment map already has mipmaps
bool generateMipmap = true; //!< set to false if the input environment map already has mipmaps
};

/**
Expand Down Expand Up @@ -237,6 +333,7 @@ class UTILS_PUBLIC IBLPrefilterContext {
utils::Entity mCameraEntity{};
filament::View* mView{};
filament::Material* mIntegrationMaterial{};
filament::Material* mIrradianceIntegrationMaterial{};
};

#endif //TNT_IBL_PREFILTER_IBLPREFILTER_H
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