feat: Implement NICE/Lanczos-3 filtering

.github/workflows/build.yml

@@ -28,14 +28,6 @@ jobs:
           arch: x64
           spectre: true
 
-      - name: Install Dependencies [macOS]
-        if: matrix.os == 'macos-latest'
-        run: brew install ninja
-
-      - name: Install Dependencies [Linux]
-        if: matrix.os == 'ubuntu-latest'
-        run: sudo apt update && sudo apt install -y ninja-build
-
       - name: Configure CMake
         run: cmake -G "Ninja" -B build -DCMAKE_BUILD_TYPE=${{matrix.build_type}} -DSOURCEPP_BUILD_TESTS=ON
 

README.md

@@ -398,6 +398,7 @@ found on PyPI in the [sourcepp](https://pypi.org/project/sourcepp) package.
 - `vpkpp`'s ORE parser is based on [reverse-engineering work](https://github.com/erysdren/narbacular-drop-tools) by [@erysdren](https://github.com/erysdren).
 - `vpkpp`'s VPP parser was contributed by [@erysdren](https://github.com/erysdren).
 - `vpkpp`'s WAD3 parser/writer was contributed by [@ozxybox](https://github.com/ozxybox).
+- `vtfpp`'s NICE/Lanczos-3 resize filter support was contributed by [@koerismo](https://github.com/koerismo).
 - `vtfpp`'s SHT parser/writer was contributed by [@Trico Everfire](https://github.com/Trico-Everfire).
 - `vtfpp`'s VTF write support is loosely based on work by [@Trico Everfire](https://github.com/Trico-Everfire).
 - `vtfpp`'s HDRI to cubemap conversion code is modified from the [HdriToCubemap](https://github.com/ivarout/HdriToCubemap) library by [@ivarout](https://github.com/ivarout).

docs/index.md

@@ -351,6 +351,7 @@ found on PyPI in the [sourcepp](https://pypi.org/project/sourcepp) package.
 - `vpkpp`'s ORE parser is based on [reverse-engineering work](https://github.com/erysdren/narbacular-drop-tools) by [@erysdren](https://github.com/erysdren).
 - `vpkpp`'s VPP parser was contributed by [@erysdren](https://github.com/erysdren).
 - `vpkpp`'s WAD3 parser/writer was contributed by [@ozxybox](https://github.com/ozxybox).
+- `vtfpp`'s NICE/Lanczos-3 resize filter support was contributed by [@koerismo](https://github.com/koerismo).
 - `vtfpp`'s SHT parser/writer was contributed by [@Trico Everfire](https://github.com/Trico-Everfire).
 - `vtfpp`'s VTF write support is loosely based on work by [@Trico Everfire](https://github.com/Trico-Everfire).
 - `vtfpp`'s HDRI to cubemap conversion code is modified from the [HdriToCubemap](https://github.com/ivarout/HdriToCubemap) library by [@ivarout](https://github.com/ivarout).

include/vtfpp/ImageConversion.h

@@ -375,6 +375,8 @@ enum class ResizeFilter {
 
 	// User-defined
 	KAISER = 100,
+	/// Valve NICE filtering, equivalent to Lanczos-3
+	NICE = 101,
 };
 
 enum class ResizeMethod {

lang/c/include/vtfppc/ImageConversion.h

@@ -38,6 +38,7 @@ typedef enum {
 	VTFPP_IMAGE_CONVERSION_RESIZE_FILTER_MITCHELL,
 	VTFPP_IMAGE_CONVERSION_RESIZE_FILTER_POINT_SAMPLE,
 	VTFPP_IMAGE_CONVERSION_RESIZE_FILTER_KAISER = 100,
+	VTFPP_IMAGE_CONVERSION_RESIZE_FILTER_NICE,
 } vtfpp_image_conversion_resize_filter_e;
 
 typedef enum {

lang/python/src/vtfpp.h

@@ -171,6 +171,7 @@ void register_python(py::module_& m) {
 			.value("MITCHELL",      ResizeFilter::MITCHELL)
 			.value("POINT_SAMPLE",  ResizeFilter::POINT_SAMPLE)
 			.value("KAISER",        ResizeFilter::KAISER)
+			.value("NICE",          ResizeFilter::NICE)
 			.export_values();
 
 		py::enum_<ResizeMethod>(ImageConversion, "ResizeMethod")

src/vtfpp/ImageConversion.cpp

@@ -1942,6 +1942,24 @@ std::vector<std::byte> ImageConversion::resizeImageData(std::span<const std::byt
 				stbir_set_filter_callbacks(&resize, KAISER_FILTER, KAISER_SUPPORT, KAISER_FILTER, KAISER_SUPPORT);
 				break;
 			}
+			case ResizeFilter::NICE: {
+				static constexpr auto SINC = [](float x) -> float {
+					if (x == 0.f) return 1.f;
+					const float a = x * math::pi_f32;
+					return sinf(a) / a;
+				};
+				static constexpr auto NICE_FILTER = [](float x, float, void*) -> float {
+					if (x >= 3.f || x <= -3.f) return 0.f;
+					return SINC(x) * SINC(x / 3.f);
+				};
+				// Normally you would max(1, invScale), but stb is weird and immediately un-scales the result when downsampling.
+				// See stb_image_resize2.h L2977 (stbir__get_filter_pixel_width)
+				static constexpr auto NICE_SUPPORT = [](float invScale, void*) -> float {
+					return invScale * 3.f;
+				};
+				stbir_set_filter_callbacks(&resize, NICE_FILTER, NICE_SUPPORT, NICE_FILTER, NICE_SUPPORT);
+				break;
+			}
 		}
 		stbir_resize_extended(&resize);
 	};