adding downscaling variant as a workaround for --dscale-antiring not …

…working on gpu-next

PixelClipper_downscaling.glsl

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+// MIT License
+
+// Copyright (c) 2023 João Chrisóstomo
+
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+//!HOOK POSTKERNEL
+//!BIND POSTKERNEL
+//!BIND PREKERNEL
+//!DESC Pixel Clipper (Anti-Ringing)
+//!WHEN POSTKERNEL.w PREKERNEL.w / 1.000 < POSTKERNEL.h PREKERNEL.h / 1.000 < *
+
+const float strength = 1.0;
+
+vec4 hook() {
+    int radius = int(ceil((PREKERNEL_size.x / POSTKERNEL_size.x) * 0.5));
+    vec4 pix = vec4(0.0);
+    vec4 min_pix = vec4(1e8);
+    vec4 max_pix = vec4(1e-8);
+
+    for (int dx = -radius; dx <= radius; dx++) {
+        for (int dy = -radius; dy <= radius; dy++) {
+            pix = PREKERNEL_texOff(vec2(dx, dy));
+            min_pix = min(pix, min_pix);
+            max_pix = max(pix, max_pix);
+        }
+    }
+
+    vec4 lr_pix = POSTKERNEL_texOff(0.0);
+    vec4 clipped = clamp(lr_pix, min_pix, max_pix);
+    return mix(lr_pix, clipped, strength);
+}