Add b-spline-4-taps and catmull-rom-5-taps

Two standalone fast cubic shaders.

interpolation/b-spline-4-taps.slangp

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+shaders = 1
+
+shader0 = shaders/b-spline-4-taps.slang
+wrap_mode0 = clamp_to_edge
+scale_type0 = viewport
+filter_linear0 = true

interpolation/catmull-rom-5-taps.slangp

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+shaders = 1
+
+shader0 = shaders/catmull-rom-5-taps.slang
+wrap_mode0 = clamp_to_edge
+scale_type0 = viewport
+filter_linear0 = true

interpolation/shaders/b-spline-4-taps.slang

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+#version 450
+
+/*
+	Bicubic B-Spline 4-taps (Fast) - ported by Hyllian - 2024
+
+	The following code is licensed under the MIT license: https://gist.github.com/TheRealMJP/bc503b0b87b643d3505d41eab8b332ae
+
+	Samples a texture with B-Spline filtering, using only 4 texture fetches instead of 16.
+	See http://vec3.ca/bicubic-filtering-in-fewer-taps/ for more details
+	Implementation: https://www.shadertoy.com/view/styXDh
+
+	ATENTION: This code only work using LINEAR filter sampling set on Retroarch!
+
+*/
+
+layout(push_constant) uniform Push
+{
+	vec4 SourceSize;
+	vec4 OriginalSize;
+	vec4 OutputSize;
+	uint FrameCount;
+} params;
+
+layout(std140, set = 0, binding = 0) uniform UBO
+{
+	mat4 MVP;
+} global;
+
+#pragma stage vertex
+layout(location = 0) in vec4 Position;
+layout(location = 1) in vec2 TexCoord;
+layout(location = 0) out vec2 vTexCoord;
+
+void main()
+{
+   gl_Position = global.MVP * Position;
+   vTexCoord = TexCoord;
+}
+
+#pragma stage fragment
+layout(location = 0) in vec2 vTexCoord;
+layout(location = 0) out vec4 FragColor;
+layout(set = 0, binding = 2) uniform sampler2D Source;
+
+void main()
+{
+    // We're going to sample a a 4x4 grid of texels surrounding the target UV coordinate. We'll do this by rounding
+    // down the sample location to get the exact center of our "starting" texel. The starting texel will be at
+    // location [1, 1] in the grid, where [0, 0] is the top left corner.
+    vec2 texSize = params.SourceSize.xy;
+    vec2 invTexSize = 1.0 / texSize;
+    vec2 iTc = vTexCoord * texSize;
+
+    vec2 tc = floor(iTc - vec2(0.5)) + vec2(0.5);
+
+    // Compute the fractional offset from our starting texel to our original sample location, which we'll
+    // feed into the B-Spline function to get our filter weights.
+    vec2 f  = iTc - tc;
+    vec2 f2 = f * f;
+    vec2 f3 = f2 * f;
+
+    vec2 of  = vec2(1.)-f;
+    vec2 of2 = of*of;
+    vec2 of3 = of2*of;
+    
+    vec2 w0 = of3 / 6.0 ;
+    vec2 w1 = (vec2(4.) + 3.*f3 - 6.*f2) / 6.0;
+    vec2 w2 = (vec2(4.) + 3.*of3 - 6.*of2) / 6.0;
+    vec2 w3 = f3 / 6.0;
+
+    vec2 Weight[2];
+    vec2 Sample[2];
+
+    Weight[0] = w0 + w1;
+    Weight[1] = w2 + w3;
+
+    Sample[0] = tc - (vec2(1.) - w1/Weight[0]);
+    Sample[1] = tc + vec2(1.)  + w3/Weight[1];
+
+    Sample[0] *= invTexSize;
+    Sample[1] *= invTexSize;
+
+    float sampleWeight[4];
+    sampleWeight[0] = Weight[0].x * Weight[0].y;
+    sampleWeight[1] = Weight[1].x * Weight[0].y;
+    sampleWeight[2] = Weight[0].x * Weight[1].y;
+    sampleWeight[3] = Weight[1].x * Weight[1].y;
+
+    vec3 Ctl = texture(Source, vec2(Sample[0].x, Sample[0].y)).rgb * sampleWeight[0];    
+    vec3 Ctr = texture(Source, vec2(Sample[1].x, Sample[0].y)).rgb * sampleWeight[1];    
+    vec3 Cbl = texture(Source, vec2(Sample[0].x, Sample[1].y)).rgb * sampleWeight[2];    
+    vec3 Cbr = texture(Source, vec2(Sample[1].x, Sample[1].y)).rgb * sampleWeight[3];
+
+    FragColor = vec4(Ctl+Ctr+Cbl+Cbr, 1.0);
+}

interpolation/shaders/catmull-rom-5-taps.slang

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+#version 450
+
+/*
+	Bicubic Catmull-Rom 5-taps (Fast) - ported by Hyllian - 2024
+
+	Samples a texture with B-Spline filtering, using only 4 texture fetches instead of 16.
+	See http://vec3.ca/bicubic-filtering-in-fewer-taps/ for more details
+	Source: https://www.shadertoy.com/view/styXDh
+	http://www.profhua.com/Sub/Article/BicubicFiltering/BicubicFiltering.html
+
+	ATENTION: This code only work using LINEAR filter sampling set on Retroarch!
+
+*/
+
+layout(push_constant) uniform Push
+{
+	vec4 SourceSize;
+	vec4 OriginalSize;
+	vec4 OutputSize;
+	uint FrameCount;
+} params;
+
+layout(std140, set = 0, binding = 0) uniform UBO
+{
+	mat4 MVP;
+} global;
+
+#pragma stage vertex
+layout(location = 0) in vec4 Position;
+layout(location = 1) in vec2 TexCoord;
+layout(location = 0) out vec2 vTexCoord;
+
+void main()
+{
+   gl_Position = global.MVP * Position;
+   vTexCoord = TexCoord;
+}
+
+#pragma stage fragment
+layout(location = 0) in vec2 vTexCoord;
+layout(location = 0) out vec4 FragColor;
+layout(set = 0, binding = 2) uniform sampler2D Source;
+
+void main()
+{
+    // We're going to sample a a 4x4 grid of texels surrounding the target UV coordinate. We'll do this by rounding
+    // down the sample location to get the exact center of our "starting" texel. The starting texel will be at
+    // location [1, 1] in the grid, where [0, 0] is the top left corner.
+    vec2 texSize = params.SourceSize.xy;
+    vec2 invTexSize = 1.0 / texSize;
+    vec2 iTc = vTexCoord * texSize;
+
+    vec2 tc = floor(iTc - vec2(0.5)) + vec2(0.5);
+
+    // Compute the fractional offset from our starting texel to our original sample location, which we'll
+    // feed into the B-Spline function to get our filter weights.
+    vec2 f  = iTc - tc;
+    vec2 f2 = f * f;
+    vec2 f3 = f2 * f;
+
+    vec2 of = vec2(1.)-f;
+    vec2 of2 = of*of;
+    vec2 of3 = of2*of;
+    
+    vec2 w0 = f2 - 0.5 * (f3 + f);
+    vec2 w1 = 1.5 * f3 - 2.5 * f2 + vec2(1.);
+    vec2 w3 = 0.5 * (f3 - f2);
+    vec2 w2 = vec2(1.) - w0 - w1 - w3;
+
+    vec2 Weight[3];
+    vec2 Sample[3];
+
+    Weight[0] = w0;
+    Weight[1] = w1 + w2;
+    Weight[2] = w3;
+
+    Sample[0] = tc - vec2(1.);
+    Sample[1] = tc + w2 / Weight[1];
+    Sample[2] = tc + vec2(2.);
+
+    Sample[0] *= invTexSize;
+    Sample[1] *= invTexSize;
+    Sample[2] *= invTexSize;
+
+    float sampleWeight[5];
+    sampleWeight[0] = Weight[1].x * Weight[0].y;
+    sampleWeight[1] = Weight[0].x * Weight[1].y;
+    sampleWeight[2] = Weight[1].x * Weight[1].y;
+    sampleWeight[3] = Weight[2].x * Weight[1].y;
+    sampleWeight[4] = Weight[1].x * Weight[2].y;
+
+    vec3 Ct = texture(Source, vec2(Sample[1].x, Sample[0].y)).rgb * sampleWeight[0];    
+    vec3 Cl = texture(Source, vec2(Sample[0].x, Sample[1].y)).rgb * sampleWeight[1];    
+    vec3 Cc = texture(Source, vec2(Sample[1].x, Sample[1].y)).rgb * sampleWeight[2];    
+    vec3 Cr = texture(Source, vec2(Sample[2].x, Sample[1].y)).rgb * sampleWeight[3];    
+    vec3 Cb = texture(Source, vec2(Sample[1].x, Sample[2].y)).rgb * sampleWeight[4];
+    
+    float WeightMultiplier = 1./(sampleWeight[0]+sampleWeight[1]+sampleWeight[2]+sampleWeight[3]+sampleWeight[4]);
+
+    FragColor = vec4((Ct+Cl+Cc+Cr+Cb)*WeightMultiplier, 1.0);
+}