add lanczos2-fast in two passes. (#524)

* Add files via upload

* Add files via upload

* change credits

* change credits

* Update lanczos2-y.glsl

* add anti-ringing

* add anti-ringing

* gles fix

windowed/lanczos2-fast.glslp

@@ -0,0 +1,13 @@
+shaders = 2
+
+shader0 = shaders/lanczos2-x.glsl
+filter_linear0 = false
+scale_type_x0 = viewport
+scale_type_y0 = source
+scale0 = 1.0
+wrap_mode0 = "clamp_to_edge"
+
+shader1 = shaders/lanczos2-y.glsl
+filter_linear1 = false
+wrap_mode1 = "clamp_to_edge"
+

windowed/shaders/lanczos2-x.glsl

@@ -0,0 +1,165 @@
+/*
+   Lanczos2 - passX 
+
+   Multipass code by dariusG 2025.
+*/
+
+
+/*
+
+This Program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+This Program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with XBMC; see the file COPYING.  If not, write to
+the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+http://www.gnu.org/copyleft/gpl.html
+*/
+
+
+#if defined(VERTEX)
+
+#if __VERSION__ >= 130
+#define COMPAT_VARYING out
+#define COMPAT_ATTRIBUTE in
+#define COMPAT_TEXTURE texture
+#else
+#define COMPAT_VARYING varying 
+#define COMPAT_ATTRIBUTE attribute 
+#define COMPAT_TEXTURE(c,d) texture(c,d)
+#endif
+
+#ifdef GL_ES
+#define COMPAT_PRECISION mediump
+precision COMPAT_PRECISION float;
+#else
+#define COMPAT_PRECISION
+#endif
+
+COMPAT_ATTRIBUTE vec4 VertexCoord;
+COMPAT_ATTRIBUTE vec4 COLOR;
+COMPAT_ATTRIBUTE vec4 TexCoord;
+COMPAT_VARYING vec4 COL0;
+COMPAT_VARYING vec4 TEX0;
+COMPAT_VARYING vec2 ps;
+
+uniform mat4 MVPMatrix;
+uniform COMPAT_PRECISION int FrameDirection;
+uniform COMPAT_PRECISION int FrameCount;
+uniform COMPAT_PRECISION vec2 OutputSize;
+uniform COMPAT_PRECISION vec2 TextureSize;
+uniform COMPAT_PRECISION vec2 InputSize;
+
+void main()
+{
+    gl_Position = MVPMatrix * VertexCoord;
+    COL0 = COLOR;
+    TEX0.xy = TexCoord.xy;
+    ps = 1.0/TextureSize.xy;
+}
+
+#elif defined(FRAGMENT)
+
+#if __VERSION__ >= 130
+#define COMPAT_VARYING in
+#define COMPAT_TEXTURE texture
+out vec4 FragColor;
+#else
+#define COMPAT_TEXTURE texture2D
+#define COMPAT_VARYING varying
+#define FragColor gl_FragColor
+
+#endif
+
+#ifdef GL_ES
+#ifdef GL_FRAGMENT_PRECISION_HIGH
+precision highp float;
+#else
+precision mediump float;
+#endif
+#define COMPAT_PRECISION mediump
+#else
+#define COMPAT_PRECISION
+#endif
+
+uniform COMPAT_PRECISION int FrameDirection;
+uniform COMPAT_PRECISION int FrameCount;
+uniform COMPAT_PRECISION vec2 OutputSize;
+uniform COMPAT_PRECISION vec2 TextureSize;
+uniform COMPAT_PRECISION vec2 InputSize;
+uniform sampler2D Texture;
+COMPAT_VARYING vec4 TEX0;
+COMPAT_VARYING vec2 ps;
+
+// compatibility #defines
+#define Source Texture
+#define vTexCoord TEX0.xy
+
+#define SourceSize vec4(TextureSize, 1.0 / TextureSize) //either TextureSize or InputSize
+#define outsize vec4(OutputSize, 1.0 / OutputSize)
+
+#ifdef PARAMETER_UNIFORM
+// All parameter floats need to have COMPAT_PRECISION in front of them
+uniform COMPAT_PRECISION float LANCZOS3_ANTI_RINGING;
+
+
+#else
+#define LANCZOS3_ANTI_RINGING 1.0
+
+#endif
+
+// Lanczos2 horizontal pass (optimized for speed on handhelds)
+
+#define RADIUS 2.0
+#define PI 3.1415926
+
+// Cheaper weight function (Lanczos2: radius 2 instead of 3)
+float weight2(float x) {
+    x = abs(x);
+    if (x == 0.0) return 1.0;
+    if (x >= RADIUS) return 0.0;
+    return (sin(PI * x) / (PI * x)) * (sin(PI * x / RADIUS) / (PI * x / RADIUS));
+}
+
+void main()
+{
+    vec2 pos = vTexCoord.xy;       // current position
+    float fx = fract(pos.x / ps.x);
+
+    // sample 4 texels around target pixel
+    float xpos = floor(pos.x / ps.x - 1.0);
+    float ypos = floor(pos.y / ps.y);
+
+    vec2 base = vec2(xpos, ypos) * ps;
+
+    vec3 C0 = COMPAT_TEXTURE(Source, base).rgb;
+    vec3 C1 = COMPAT_TEXTURE(Source, base + vec2(ps.x, 0.0)).rgb;
+    vec3 C2 = COMPAT_TEXTURE(Source, base + vec2(ps.x*2.0, 0.0)).rgb;
+    vec3 C3 = COMPAT_TEXTURE(Source, base + vec2(ps.x*3.0, 0.0)).rgb;
+
+    // weights for 4 samples (Lanczos2 kernel)
+    float w0 = weight2(fx + 1.0);
+    float w1 = weight2(fx);
+    float w2 = weight2(1.0 - fx);
+    float w3 = weight2(2.0 - fx);
+
+    float sum = w0 + w1 + w2 + w3;
+    w0 /= sum; w1 /= sum; w2 /= sum; w3 /= sum;
+
+    vec3 color = C0*w0 + C1*w1 + C2*w2 + C3*w3;
+   
+    // --- Lightweight anti-ringing ---
+    vec3 min_sample = min(min(C0, C1), min(C2, C3));
+    vec3 max_sample = max(max(C0, C1), max(C2, C3));
+    color = clamp(color, min_sample, max_sample);
+
+    FragColor = vec4(color, 1.0);
+}
+#endif

windowed/shaders/lanczos2-y.glsl

@@ -0,0 +1,165 @@
+/*
+   Lanczos2 - passY 
+
+   Multipass code by dariusG 2025.
+
+*/
+
+
+/*
+
+This Program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+This Program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with XBMC; see the file COPYING.  If not, write to
+the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+http://www.gnu.org/copyleft/gpl.html
+*/
+
+#if defined(VERTEX)
+
+#if __VERSION__ >= 130
+#define COMPAT_VARYING out
+#define COMPAT_ATTRIBUTE in
+#define COMPAT_TEXTURE texture
+#else
+#define COMPAT_VARYING varying 
+#define COMPAT_ATTRIBUTE attribute 
+#define COMPAT_TEXTURE(c,d) texture(c,d)
+#endif
+
+#ifdef GL_ES
+#define COMPAT_PRECISION mediump
+precision COMPAT_PRECISION float;
+#else
+#define COMPAT_PRECISION
+#endif
+
+COMPAT_ATTRIBUTE vec4 VertexCoord;
+COMPAT_ATTRIBUTE vec4 COLOR;
+COMPAT_ATTRIBUTE vec4 TexCoord;
+COMPAT_VARYING vec4 COL0;
+COMPAT_VARYING vec4 TEX0;
+COMPAT_VARYING vec2 ps;
+
+uniform mat4 MVPMatrix;
+uniform COMPAT_PRECISION int FrameDirection;
+uniform COMPAT_PRECISION int FrameCount;
+uniform COMPAT_PRECISION vec2 OutputSize;
+uniform COMPAT_PRECISION vec2 TextureSize;
+uniform COMPAT_PRECISION vec2 InputSize;
+
+void main()
+{
+    gl_Position = MVPMatrix * VertexCoord;
+    COL0 = COLOR;
+    TEX0.xy = TexCoord.xy;
+    ps = 1.0/TextureSize.xy;
+}
+
+#elif defined(FRAGMENT)
+
+#if __VERSION__ >= 130
+#define COMPAT_VARYING in
+#define COMPAT_TEXTURE texture
+out vec4 FragColor;
+#else
+#define COMPAT_TEXTURE texture2D
+#define COMPAT_VARYING varying
+#define FragColor gl_FragColor
+
+#endif
+
+#ifdef GL_ES
+#ifdef GL_FRAGMENT_PRECISION_HIGH
+precision highp float;
+#else
+precision mediump float;
+#endif
+#define COMPAT_PRECISION mediump
+#else
+#define COMPAT_PRECISION
+#endif
+
+uniform COMPAT_PRECISION int FrameDirection;
+uniform COMPAT_PRECISION int FrameCount;
+uniform COMPAT_PRECISION vec2 OutputSize;
+uniform COMPAT_PRECISION vec2 TextureSize;
+uniform COMPAT_PRECISION vec2 InputSize;
+uniform sampler2D Texture;
+COMPAT_VARYING vec4 TEX0;
+COMPAT_VARYING vec2 ps;
+
+// compatibility #defines
+#define Source Texture
+#define vTexCoord TEX0.xy
+
+#define SourceSize vec4(TextureSize, 1.0 / TextureSize) //either TextureSize or InputSize
+#define outsize vec4(OutputSize, 1.0 / OutputSize)
+
+#ifdef PARAMETER_UNIFORM
+// All parameter floats need to have COMPAT_PRECISION in front of them
+uniform COMPAT_PRECISION float LANCZOS3_ANTI_RINGING;
+
+
+#else
+#define LANCZOS3_ANTI_RINGING 1.0
+
+#endif
+
+// Lanczos2 vertical pass (optimized for handhelds)
+
+#define PI 3.1415926535897932384626433832795
+#define RADIUS 2.0
+
+float weight2(float x) {
+    x = abs(x);
+    if (x == 0.0) return 1.0;
+    if (x >= RADIUS) return 0.0;
+    return (sin(PI * x) / (PI * x)) * (sin(PI * x / RADIUS) / (PI * x / RADIUS));
+}
+
+void main()
+{
+    vec2 pos = vTexCoord.xy;       // current position
+    float fy = fract(pos.y / ps.y);
+
+    // sample 4 texels around target pixel (vertical instead of horizontal)
+    float xpos = floor(pos.x / ps.x);
+    float ypos = floor(pos.y / ps.y - 1.0);
+
+    vec2 base = vec2(xpos, ypos) * ps;
+
+    vec3 C0 = COMPAT_TEXTURE(Source, base).rgb;
+    vec3 C1 = COMPAT_TEXTURE(Source, base + vec2(0.0, ps.y)).rgb;
+    vec3 C2 = COMPAT_TEXTURE(Source, base + vec2(0.0, ps.y*2.0)).rgb;
+    vec3 C3 = COMPAT_TEXTURE(Source, base + vec2(0.0, ps.y*3.0)).rgb;
+
+    // weights for 4 samples (Lanczos2 kernel)
+    float w0 = weight2(fy + 1.0);
+    float w1 = weight2(fy);
+    float w2 = weight2(1.0 - fy);
+    float w3 = weight2(2.0 - fy);
+
+    float sum = w0 + w1 + w2 + w3;
+    w0 /= sum; w1 /= sum; w2 /= sum; w3 /= sum;
+
+    vec3 color = C0*w0 + C1*w1 + C2*w2 + C3*w3;
+    
+    // --- Lightweight anti-ringing ---
+    vec3 min_sample = min(min(C0, C1), min(C2, C3));
+    vec3 max_sample = max(max(C0, C1), max(C2, C3));
+    color = clamp(color, min_sample, max_sample);
+
+    FragColor = vec4(color, 1.0);
+}
+
+#endif