Vulkan: Add MMPX upscaling texture shader.

See https://casual-effects.com/research/McGuire2021PixelArt/index.html
hrydgard · Jan 28, 2021 · c99b4b1 · c99b4b1
1 parent a2023a1
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diff --git a/assets/shaders/defaultshaders.ini b/assets/shaders/defaultshaders.ini
@@ -154,3 +154,8 @@ Type=Texture
 Name=4xBRZ
 Author=Hyllian
 Compute=tex_4xbrz.csh
+[TexMMPX]
+Type=Texture
+Name=MMPX
+Author=Morgan McGuire and Mara Gagiu
+Compute=tex_mmpx.csh
diff --git a/assets/shaders/tex_mmpx.csh b/assets/shaders/tex_mmpx.csh
@@ -0,0 +1,117 @@
+/* MMPX.glc
+   Copyright 2020 Morgan McGuire & Mara Gagiu. 
+   Provided under the Open Source MIT license https://opensource.org/licenses/MIT
+
+   See js-demo.html for the commented source code.
+   This is an optimized GLSL port of that version
+   by Morgan McGuire and Mara Gagiu.
+*/
+
+#define ABGR8 uint
+
+ABGR8 src(int x, int y) {
+    return readColoru(uvec2(clamp(x, 0, params.width - 1), clamp(y, 0, params.height - 1)));
+}
+
+uint luma(ABGR8 C) {
+    uint alpha = (C & 0xFF000000u) >> 24;
+    return (((C & 0x00FF0000u) >> 16) + ((C & 0x0000FF00u) >> 8) + (C & 0x000000FFu) + 1u) * (256u - alpha);
+}
+
+bool all_eq2(ABGR8 B, ABGR8 A0, ABGR8 A1) {
+    return ((B ^ A0) | (B ^ A1)) == 0u;
+}
+
+bool all_eq3(ABGR8 B, ABGR8 A0, ABGR8 A1, ABGR8 A2) {
+    return ((B ^ A0) | (B ^ A1) | (B ^ A2)) == 0u;
+}
+
+bool all_eq4(ABGR8 B, ABGR8 A0, ABGR8 A1, ABGR8 A2, ABGR8 A3) {
+    return ((B ^ A0) | (B ^ A1) | (B ^ A2) | (B ^ A3)) == 0u;
+}
+
+bool any_eq3(ABGR8 B, ABGR8 A0, ABGR8 A1, ABGR8 A2) {
+    return B == A0 || B == A1 || B == A2;
+}
+
+bool none_eq2(ABGR8 B, ABGR8 A0, ABGR8 A1) {
+    return (B != A0) && (B != A1);
+}
+
+bool none_eq4(ABGR8 B, ABGR8 A0, ABGR8 A1, ABGR8 A2, ABGR8 A3) {
+    return B != A0 && B != A1 && B != A2 && B != A3;
+}
+
+uint applyScalingu(uvec2 origxy, uvec2 xy) {
+    int srcX = int(origxy.x);
+    int srcY = int(origxy.y);
+
+    ABGR8 A = src(srcX - 1, srcY - 1), B = src(srcX, srcY - 1), C = src(srcX + 1, srcY - 1);
+    ABGR8 D = src(srcX - 1, srcY + 0), E = src(srcX, srcY + 0), F = src(srcX + 1, srcY + 0);
+    ABGR8 G = src(srcX - 1, srcY + 1), H = src(srcX, srcY + 1), I = src(srcX + 1, srcY + 1);
+
+    ABGR8 J = E, K = E, L = E, M = E;
+
+    if (((A ^ E) | (B ^ E) | (C ^ E) | (D ^ E) | (F ^ E) | (G ^ E) | (H ^ E) | (I ^ E)) != 0u) {
+        ABGR8 P = src(srcX, srcY - 2), S = src(srcX, srcY + 2);
+        ABGR8 Q = src(srcX - 2, srcY), R = src(srcX + 2, srcY);
+        ABGR8 Bl = luma(B), Dl = luma(D), El = luma(E), Fl = luma(F), Hl = luma(H);
+
+        // 1:1 slope rules
+        if ((D == B && D != H && D != F) && (El >= Dl || E == A) && any_eq3(E, A, C, G) && ((El < Dl) || A != D || E != P || E != Q)) J = D;
+        if ((B == F && B != D && B != H) && (El >= Bl || E == C) && any_eq3(E, A, C, I) && ((El < Bl) || C != B || E != P || E != R)) K = B;
+        if ((H == D && H != F && H != B) && (El >= Hl || E == G) && any_eq3(E, A, G, I) && ((El < Hl) || G != H || E != S || E != Q)) L = H;
+        if ((F == H && F != B && F != D) && (El >= Fl || E == I) && any_eq3(E, C, G, I) && ((El < Fl) || I != H || E != R || E != S)) M = F;
+
+        // Intersection rules
+        if ((E != F && all_eq4(E, C, I, D, Q) && all_eq2(F, B, H)) && (F != src(srcX + 3, srcY))) K = M = F;
+        if ((E != D && all_eq4(E, A, G, F, R) && all_eq2(D, B, H)) && (D != src(srcX - 3, srcY))) J = L = D;
+        if ((E != H && all_eq4(E, G, I, B, P) && all_eq2(H, D, F)) && (H != src(srcX, srcY + 3))) L = M = H;
+        if ((E != B && all_eq4(E, A, C, H, S) && all_eq2(B, D, F)) && (B != src(srcX, srcY - 3))) J = K = B;
+        if (Bl < El && all_eq4(E, G, H, I, S) && none_eq4(E, A, D, C, F)) J = K = B;
+        if (Hl < El && all_eq4(E, A, B, C, P) && none_eq4(E, D, G, I, F)) L = M = H;
+        if (Fl < El && all_eq4(E, A, D, G, Q) && none_eq4(E, B, C, I, H)) K = M = F;
+        if (Dl < El && all_eq4(E, C, F, I, R) && none_eq4(E, B, A, G, H)) J = L = D;
+
+        // 2:1 slope rules
+        if (H != B) { 
+            if (H != A && H != E && H != C) {
+                if (all_eq3(H, G, F, R) && none_eq2(H, D, src(srcX + 2, srcY - 1))) L = M;
+                if (all_eq3(H, I, D, Q) && none_eq2(H, F, src(srcX - 2, srcY - 1))) M = L;
+            }
+
+            if (B != I && B != G && B != E) {
+                if (all_eq3(B, A, F, R) && none_eq2(B, D, src(srcX + 2, srcY + 1))) J = K;
+                if (all_eq3(B, C, D, Q) && none_eq2(B, F, src(srcX - 2, srcY + 1))) K = J;
+            }
+        } // H !== B
+
+        if (F != D) { 
+            if (D != I && D != E && D != C) {
+                if (all_eq3(D, A, H, S) && none_eq2(D, B, src(srcX + 1, srcY + 2))) J = L;
+                if (all_eq3(D, G, B, P) && none_eq2(D, H, src(srcX + 1, srcY - 2))) L = J;
+            }
+
+            if (F != E && F != A && F != G) {    
+                if (all_eq3(F, C, H, S) && none_eq2(F, B, src(srcX - 1, srcY + 2))) K = M;
+                if (all_eq3(F, I, B, P) && none_eq2(F, H, src(srcX - 1, srcY - 2))) M = K;
+            }
+        } // F !== D
+    } // not constant
+
+    // TODO: Write four pixels at once.  For now, 1/4x speed.
+    if ((xy.y & 1u) == 0u) {
+        if ((xy.x & 1u) == 0u) {
+            return J;
+        }
+        return K;
+    }
+    if ((xy.x & 1u) == 0u) {
+        return L;
+    }
+    return M;
+}
+
+vec4 applyScalingf(uvec2 origxy, uvec2 xy) {
+	return unpackUnorm4x8(applyScalingu(origxy, xy));
+}