Feature - Adds Dual Kawase Blur filter. (#10)

* Adds Interpolated Dual Kawase blur filter, allowing for very high blur radius with extremely efficient computation.
* Improved handling of UI changes between blur algorithms.

CMakeLists.txt

@@ -31,6 +31,8 @@ target_sources(${PROJECT_NAME} PRIVATE
 	src/blur/box.h
 	src/blur/pixelate.c
 	src/blur/pixelate.h
+	src/blur/dual_kawase.c
+	src/blur/dual_kawase.h
 	src/version.h)
 
 if(BUILD_OUT_OF_TREE)

data/locale/en-US.ini

@@ -14,16 +14,18 @@ CompositeBlurFilter.TiltShift.Width="Thickness"
 CompositeBlurFilter.TiltShift.Angle="Angle"
 CompositeBlurFilter.Algorithm.Gaussian="Gaussian"
 CompositeBlurFilter.Algorithm.Box="Box"
-CompositeBlurFilter.Algorithm.Kawase="Kawase"
+CompositeBlurFilter.Algorithm.DualKawase="Dual Kawase"
 CompositeBlurFilter.Algorithm.Pixelate="Pixelate"
 CompositeBlurFilter.Type.Area="Area"
 CompositeBlurFilter.Type.Directional="Directional"
 CompositeBlurFilter.Type.Zoom="Zoom"
 CompositeBlurFilter.Type.Motion="Motion"
 CompositeBlurFilter.Type.TiltShift="Tilt-Shift"
 CompositeBlurFilter.PixelateType="Pixelate Type"
+CompositeBlurFilter.Pixelate.PixelSize="Pixel Size"
 CompositeBlurFilter.Pixelate.Square="Square"
 CompositeBlurFilter.Pixelate.Hexagonal="Hexagonal"
 CompositeBlurFilter.Pixelate.Triakis="Triakis"
 CompositeBlurFilter.Pixelate.Circle="Circle"
-CompositeBlurFilter.Pixelate.Triangle="Triangle"
+CompositeBlurFilter.Pixelate.Triangle="Triangle"
+CompositeBlurFilter.DualKawase.Passes="Blur Radius"

data/shaders/dual_kawase_down_sample.effect

@@ -0,0 +1,44 @@
+uniform float4x4 ViewProj;
+uniform texture2d image;
+uniform float2 texel_step;
+
+sampler_state textureSampler{
+    Filter = Linear;
+    AddressU = Clamp;
+    AddressV = Clamp;
+    MinLOD = 0;
+    MaxLOD = 0;
+};
+
+struct VertData {
+    float4 pos : POSITION;
+    float2 uv : TEXCOORD0;
+};
+
+VertData mainTransform(VertData v_in)
+{
+    v_in.pos = mul(float4(v_in.pos.xyz, 1.0), ViewProj);
+    return v_in;
+}
+
+float4 mainImage(VertData v_in) : TARGET
+{
+    // Downsample filter as defined here:
+    // https://blog.en.uwa4d.com/2022/09/06/screen-post-processing-effects-chapter-5-dual-blur-and-its-implementation/
+    float4 col       = image.Sample(textureSampler, v_in.uv);
+    float4 col_dn_rt = image.Sample(textureSampler, v_in.uv + 0.5f*texel_step);
+    float4 col_dn_lt = image.Sample(textureSampler, v_in.uv + 0.5f*float2(-texel_step.x, texel_step.y));
+    float4 col_up_rt = image.Sample(textureSampler, v_in.uv + 0.5f*float2(texel_step.x, -texel_step.y));
+    float4 col_up_lt = image.Sample(textureSampler, v_in.uv - 0.5f*texel_step);
+
+    return (4.0*col + col_dn_rt + col_dn_lt + col_up_rt + col_up_lt)/8.0;
+}
+
+technique Draw
+{
+    pass
+    {
+        vertex_shader = mainTransform(v_in);
+        pixel_shader = mainImage(v_in);
+    }
+}

data/shaders/dual_kawase_up_sample.effect

@@ -0,0 +1,47 @@
+uniform float4x4 ViewProj;
+uniform texture2d image;
+uniform float2 texel_step;
+
+sampler_state textureSampler{
+    Filter = Linear;
+    AddressU = Clamp;
+    AddressV = Clamp;
+    MinLOD = 0;
+    MaxLOD = 0;
+};
+
+struct VertData {
+    float4 pos : POSITION;
+    float2 uv : TEXCOORD0;
+};
+
+VertData mainTransform(VertData v_in)
+{
+    v_in.pos = mul(float4(v_in.pos.xyz, 1.0), ViewProj);
+    return v_in;
+}
+
+float4 mainImage(VertData v_in) : TARGET
+{
+    // Upsample filter as defined here:
+    // https://blog.en.uwa4d.com/2022/09/06/screen-post-processing-effects-chapter-5-dual-blur-and-its-implementation/
+    float4 col_dn    = image.Sample(textureSampler, v_in.uv + float2(0.0f,  texel_step.y));
+    float4 col_up    = image.Sample(textureSampler, v_in.uv + float2(0.0f, -texel_step.y));
+    float4 col_rt    = image.Sample(textureSampler, v_in.uv + float2( texel_step.x, 0.0f));
+    float4 col_lt    = image.Sample(textureSampler, v_in.uv + float2(-texel_step.x, 0.0f));
+    float4 col_dn_rt = image.Sample(textureSampler, v_in.uv + 0.5f*texel_step) * 2.0f;
+    float4 col_dn_lt = image.Sample(textureSampler, v_in.uv + 0.5f*float2(-texel_step.x,  texel_step.y)) * 2.0f;
+    float4 col_up_rt = image.Sample(textureSampler, v_in.uv + 0.5f*float2( texel_step.x, -texel_step.y)) * 2.0f;
+    float4 col_up_lt = image.Sample(textureSampler, v_in.uv - 0.5f*texel_step) * 2.0f;
+
+    return (col_dn + col_up + col_rt + col_lt + col_dn_rt + col_dn_lt + col_up_rt + col_up_lt)/12.0f;
+}
+
+technique Draw
+{
+    pass
+    {
+        vertex_shader = mainTransform(v_in);
+        pixel_shader = mainImage(v_in);
+    }
+}

data/shaders/mix.effect

@@ -0,0 +1,41 @@
+uniform float4x4 ViewProj;
+uniform texture2d image;
+uniform texture2d image2;
+
+uniform float ratio;
+
+sampler_state textureSampler{
+    Filter = Linear;
+    AddressU = Clamp;
+    AddressV = Clamp;
+    MinLOD = 0;
+    MaxLOD = 0;
+};
+
+struct VertData {
+    float4 pos : POSITION;
+    float2 uv : TEXCOORD0;
+};
+
+VertData mainTransform(VertData v_in)
+{
+    v_in.pos = mul(float4(v_in.pos.xyz, 1.0), ViewProj);
+    return v_in;
+}
+
+float4 mainImage(VertData v_in) : TARGET
+{
+    // 1. Sample incoming pixel
+    float4 c1 = image.Sample(textureSampler, v_in.uv);
+    float4 c2 = image2.Sample(textureSampler, v_in.uv);
+    return lerp(c1, c2, float4(ratio, ratio, ratio, ratio));
+}
+
+technique Draw
+{
+    pass
+    {
+        vertex_shader = mainTransform(v_in);
+        pixel_shader = mainImage(v_in);
+    }
+}