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Add an option to clamp HDR exposure to reduce environment fireflies

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HDRI panoramas designed for realistic lighting can have extremely
bright suns, causing fireflies to appear in the environment reflection
(in addition to making environment lighting too bright when a
DirectionalLight3D is used).

This uses the Filament tonemapping formula.
This commit is contained in:
Hugo Locurcio 2022-02-16 01:43:44 +01:00
parent f94ada39b3
commit 2694138060
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GPG key ID: 39E8F8BE30B0A49C
1 changed files with 30 additions and 0 deletions
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30
editor/import/resource_importer_texture.cpp
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@ -217,6 +217,7 @@ void ResourceImporterTexture::get_import_options(const String &p_path, List<Impo
r_options->push_back(ImportOption(PropertyInfo(Variant::BOOL, "process/premult_alpha"), false));
r_options->push_back(ImportOption(PropertyInfo(Variant::BOOL, "process/normal_map_invert_y"), false));
r_options->push_back(ImportOption(PropertyInfo(Variant::BOOL, "process/hdr_as_srgb"), false));
r_options->push_back(ImportOption(PropertyInfo(Variant::BOOL, "process/hdr_clamp_exposure"), false));
r_options->push_back(ImportOption(PropertyInfo(Variant::INT, "process/size_limit", PROPERTY_HINT_RANGE, "0,4096,1"), 0));
r_options->push_back(ImportOption(PropertyInfo(Variant::INT, "detect_3d/compress_to", PROPERTY_HINT_ENUM, "Disabled,VRAM Compressed,Basis Universal"), (p_preset == PRESET_DETECT) ? 1 : 0));
@ -411,6 +412,7 @@ Error ResourceImporterTexture::import(const String &p_source_file, const String
const bool stream = p_options["compress/streamed"];
const int size_limit = p_options["process/size_limit"];
const bool hdr_as_srgb = p_options["process/hdr_as_srgb"];
const bool hdr_clamp_exposure = p_options["process/hdr_clamp_exposure"];
const int normal = p_options["compress/normal_map"];
const int hdr_compression = p_options["compress/hdr_compression"];
const int bptc_ldr = p_options["compress/bptc_ldr"];
@ -482,6 +484,34 @@ Error ResourceImporterTexture::import(const String &p_source_file, const String
}
}
if (hdr_clamp_exposure) {
// Clamp HDR exposure following Filament's tonemapping formula.
// This can be used to reduce fireflies in environment maps or reduce the influence
// of the sun from an HDRI panorama on environment lighting (when a DirectionalLight3D is used instead).
const int height = image->get_height();
const int width = image->get_width();
// These values are chosen arbitrarily and seem to produce good results with 4,096 samples.
const float linear = 4096.0;
const float compressed = 16384.0;
for (int i = 0; i < width; i++) {
for (int j = 0; j < height; j++) {
const Color color = image->get_pixel(i, j);
const float luma = color.get_luminance();
Color clamped_color;
if (luma <= linear) {
clamped_color = color;
} else {
clamped_color = (color / luma) * ((linear * linear - compressed * luma) / (2 * linear - compressed - luma));
}
image->set_pixel(i, j, clamped_color);
}
}
}
if (compress_mode == COMPRESS_BASIS_UNIVERSAL && image->get_format() >= Image::FORMAT_RF) {
//basis universal does not support float formats, fall back
compress_mode = COMPRESS_VRAM_COMPRESSED;