add spline-1 filter

Signed-off-by: lizzie <lizzie@eden-emu.dev>

src/common/settings_enums.h

@@ -166,7 +166,7 @@ ENUM(ResolutionSetup,
      Res7X,
      Res8X);
 
-ENUM(ScalingFilter, NearestNeighbor, Bilinear, Bicubic, Gaussian, Lanczos, ScaleForce, Fsr, Area, MaxEnum);
+ENUM(ScalingFilter, NearestNeighbor, Bilinear, Bicubic, Spline1, Gaussian, Lanczos, ScaleForce, Fsr, Area, MaxEnum);
 
 ENUM(AntiAliasing, None, Fxaa, Smaa, MaxEnum);
 

src/qt_common/shared_translation.cpp

@@ -572,6 +572,7 @@ std::unique_ptr<ComboboxTranslationMap> ComboboxEnumeration(QObject* parent)
                               PAIR(ScalingFilter, NearestNeighbor, tr("Nearest Neighbor")),
                               PAIR(ScalingFilter, Bilinear, tr("Bilinear")),
                               PAIR(ScalingFilter, Bicubic, tr("Bicubic")),
+                              PAIR(ScalingFilter, Spline1, tr("Spline-1")),
                               PAIR(ScalingFilter, Gaussian, tr("Gaussian")),
                               PAIR(ScalingFilter, Lanczos, tr("Lanczos")),
                               PAIR(ScalingFilter, ScaleForce, tr("ScaleForce")),

src/qt_common/shared_translation.h

@@ -38,6 +38,8 @@ static const std::map<Settings::ScalingFilter, QString> scaling_filter_texts_map
     {Settings::ScalingFilter::Bilinear,
      QStringLiteral(QT_TRANSLATE_NOOP("GMainWindow", "Bilinear"))},
     {Settings::ScalingFilter::Bicubic, QStringLiteral(QT_TRANSLATE_NOOP("GMainWindow", "Bicubic"))},
+     {Settings::ScalingFilter::Spline1,
+     QStringLiteral(QT_TRANSLATE_NOOP("GMainWindow", "Spline-1"))},
     {Settings::ScalingFilter::Gaussian,
      QStringLiteral(QT_TRANSLATE_NOOP("GMainWindow", "Gaussian"))},
      {Settings::ScalingFilter::Lanczos,

src/video_core/host_shaders/CMakeLists.txt

@@ -46,6 +46,7 @@ set(SHADER_FILES
     present_bicubic.frag
     present_gaussian.frag
     present_lanczos.frag
+    present_spline1.frag
     queries_prefix_scan_sum.comp
     queries_prefix_scan_sum_nosubgroups.comp
     resolve_conditional_render.comp

src/video_core/host_shaders/present_spline1.frag

@@ -0,0 +1,24 @@
+// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+// Spline (smooth linear inerpolation) with 1 texel fetch (needs bilinear to work)
+// Emulates bicubic without actually doing bicubic
+// See https://iquilezles.org/articles/texture, unfortunely there are issues with the original
+// where smoothstep "expansion" actually results in worse codegen (SPIRV-Opt does a direct conv to smoothstep)
+// TODO: Numerical analysis - fract is sawtooth func and floor, reuse params? Perhaps - no need for precision
+
+#version 460 core
+
+layout (location = 0) in vec2 frag_tex_coord;
+layout (location = 0) out vec4 color;
+layout (binding = 0) uniform sampler2D color_texture;
+
+vec4 textureSpline1(sampler2D sam, vec2 uv) {
+    float r = float(textureSize(sam, 0).x);
+    vec2 x = fract(uv * r + 0.5);
+    return texture(sam, (floor(uv * r + 0.5) + smoothstep(0.0, 1.0, x) - 0.5) / r);
+}
+
+void main() {
+    color = textureSpline1(color_texture, frag_tex_coord);
+}

src/video_core/renderer_opengl/gl_blit_screen.cpp

@@ -89,6 +89,9 @@ void BlitScreen::CreateWindowAdapt() {
     case Settings::ScalingFilter::Gaussian:
         window_adapt = MakeGaussian(device);
         break;
+    case Settings::ScalingFilter::Spline1:
+        window_adapt = MakeSpline1(device);
+        break;
     case Settings::ScalingFilter::Lanczos:
         window_adapt = MakeLanczos(device);
         break;

src/video_core/renderer_opengl/present/filters.cpp

@@ -28,6 +28,11 @@ std::unique_ptr<WindowAdaptPass> MakeBilinear(const Device& device) {
                                              HostShaders::OPENGL_PRESENT_FRAG);
 }
 
+std::unique_ptr<WindowAdaptPass> MakeSpline1(const Device& device) {
+    return std::make_unique<WindowAdaptPass>(device, CreateBilinearSampler(),
+                                             HostShaders::PRESENT_SPLINE1_FRAG);
+}
+
 std::unique_ptr<WindowAdaptPass> MakeBicubic(const Device& device) {
     return std::make_unique<WindowAdaptPass>(device, CreateBilinearSampler(),
                                              HostShaders::PRESENT_BICUBIC_FRAG);

src/video_core/renderer_opengl/present/filters.h

@@ -18,6 +18,7 @@ std::unique_ptr<WindowAdaptPass> MakeNearestNeighbor(const Device& device);
 std::unique_ptr<WindowAdaptPass> MakeBilinear(const Device& device);
 std::unique_ptr<WindowAdaptPass> MakeBicubic(const Device& device);
 std::unique_ptr<WindowAdaptPass> MakeGaussian(const Device& device);
+std::unique_ptr<WindowAdaptPass> MakeSpline1(const Device& device);
 std::unique_ptr<WindowAdaptPass> MakeLanczos(const Device& device);
 std::unique_ptr<WindowAdaptPass> MakeScaleForce(const Device& device);
 std::unique_ptr<WindowAdaptPass> MakeArea(const Device& device);

src/video_core/renderer_vulkan/present/filters.cpp

@@ -46,6 +46,11 @@ std::unique_ptr<WindowAdaptPass> MakeBilinear(const Device& device, VkFormat fra
                                              BuildShader(device, VULKAN_PRESENT_FRAG_SPV));
 }
 
+std::unique_ptr<WindowAdaptPass> MakeSpline1(const Device& device, VkFormat frame_format) {
+    return std::make_unique<WindowAdaptPass>(device, frame_format, CreateBilinearSampler(device),
+                                             BuildShader(device, PRESENT_SPLINE1_FRAG_SPV));
+}
+
 std::unique_ptr<WindowAdaptPass> MakeBicubic(const Device& device, VkFormat frame_format) {
     // No need for handrolled shader -- if the VK impl can do it for us ;)
     if (device.IsExtFilterCubicSupported())

src/video_core/renderer_vulkan/present/filters.h

@@ -18,6 +18,7 @@ class MemoryAllocator;
 std::unique_ptr<WindowAdaptPass> MakeNearestNeighbor(const Device& device, VkFormat frame_format);
 std::unique_ptr<WindowAdaptPass> MakeBilinear(const Device& device, VkFormat frame_format);
 std::unique_ptr<WindowAdaptPass> MakeBicubic(const Device& device, VkFormat frame_format);
+std::unique_ptr<WindowAdaptPass> MakeSpline1(const Device& device, VkFormat frame_format);
 std::unique_ptr<WindowAdaptPass> MakeGaussian(const Device& device, VkFormat frame_format);
 std::unique_ptr<WindowAdaptPass> MakeLanczos(const Device& device, VkFormat frame_format);
 std::unique_ptr<WindowAdaptPass> MakeScaleForce(const Device& device, VkFormat frame_format);

src/video_core/renderer_vulkan/vk_blit_screen.cpp

@@ -43,6 +43,9 @@ void BlitScreen::SetWindowAdaptPass() {
     case Settings::ScalingFilter::Bicubic:
         window_adapt = MakeBicubic(device, swapchain_view_format);
         break;
+    case Settings::ScalingFilter::Spline1:
+        window_adapt = MakeSpline1(device, swapchain_view_format);
+        break;
     case Settings::ScalingFilter::Gaussian:
         window_adapt = MakeGaussian(device, swapchain_view_format);
         break;