--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/shaders/xBRZ.f.glsl	Sun Apr 28 23:22:37 2024 -0700
@@ -0,0 +1,297 @@
+// xBRZ freescale
+// based on :
+
+/*
+   Hyllian's xBR-vertex code and texel mapping
+   
+   Copyright (C) 2011/2016 Hyllian - sergiogdb@gmail.com
+
+   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.
+
+*/ 
+
+// This shader also uses code and/or concepts from xBRZ as it appears
+// in the Desmume source code. The license for which is as follows:
+
+// ****************************************************************************
+// * This file is part of the HqMAME project. It is distributed under         *
+// * GNU General Public License: http://www.gnu.org/licenses/gpl-3.0          *
+// * Copyright (C) Zenju (zenju AT gmx DOT de) - All Rights Reserved          *
+// *                                                                          *
+// * Additionally and as a special exception, the author gives permission     *
+// * to link the code of this program with the MAME library (or with modified *
+// * versions of MAME that use the same license as MAME), and distribute      *
+// * linked combinations including the two. You must obey the GNU General     *
+// * Public License in all respects for all of the code used other than MAME. *
+// * If you modify this file, you may extend this exception to your version   *
+// * of the file, but you are not obligated to do so. If you do not wish to   *
+// * do so, delete this exception statement from your version.                *
+// ****************************************************************************
+// ported to blastem shader format by hunterk
+
+uniform sampler2D textures[2];
+uniform mediump vec2 texsize;
+varying mediump vec2 texcoord;
+
+#define BLEND_NONE 0
+#define BLEND_NORMAL 1
+#define BLEND_DOMINANT 2
+#define LUMINANCE_WEIGHT 1.0
+#define EQUAL_COLOR_TOLERANCE 30.0/255.0
+#define STEEP_DIRECTION_THRESHOLD 2.2
+#define DOMINANT_DIRECTION_THRESHOLD 3.6
+
+// this is usually handled automatically but blastem doesn't expose output size?
+#define scale vec2(10.0, 10.0)
+
+mediump float DistYCbCr(vec3 pixA, vec3 pixB)
+{
+  const vec3 w = vec3(0.2627, 0.6780, 0.0593);
+  const float scaleB = 0.5 / (1.0 - w.b);
+  const float scaleR = 0.5 / (1.0 - w.r);
+  vec3 diff = pixA - pixB;
+  float Y = dot(diff.rgb, w);
+  float Cb = scaleB * (diff.b - Y);
+  float Cr = scaleR * (diff.r - Y);
+
+  return sqrt(((LUMINANCE_WEIGHT * Y) * (LUMINANCE_WEIGHT * Y)) + (Cb * Cb) + (Cr * Cr));
+}
+
+bool IsPixEqual(const vec3 pixA, const vec3 pixB)
+{
+  return (DistYCbCr(pixA, pixB) < EQUAL_COLOR_TOLERANCE);
+}
+
+mediump float get_left_ratio(vec2 center, vec2 origin, vec2 direction, vec2 scale_)
+{
+  vec2 P0 = center - origin;
+  vec2 proj = direction * (dot(P0, direction) / dot(direction, direction));
+  vec2 distv = P0 - proj;
+  vec2 orth = vec2(-direction.y, direction.x);
+  float side = sign(dot(P0, orth));
+  float v = side * length(distv * scale_);
+
+//  return step(0, v);
+  return smoothstep(-sqrt(2.0)/2.0, sqrt(2.0)/2.0, v);
+}
+
+#define eq(a,b)  (a == b)
+#define neq(a,b) (a != b)
+
+#define P(x,y) texture2D(textures[0], coord + (1.0 / texsize) * vec2(x, y)).rgb
+
+void main()
+{
+  //---------------------------------------
+  // Input Pixel Mapping:  -|x|x|x|-
+  //                       x|A|B|C|x
+  //                       x|D|E|F|x
+  //                       x|G|H|I|x
+  //                       -|x|x|x|-
+
+  vec2 pos = fract(texcoord * texsize.xy) - vec2(0.5, 0.5);
+  vec2 coord = texcoord - pos * (1.0 / texsize.xy);
+  
+  vec3 A = P(-1,-1);
+  vec3 B = P( 0,-1);
+  vec3 C = P( 1,-1);
+  vec3 D = P(-1, 0);
+  vec3 E = P( 0, 0);
+  vec3 F = P( 1, 0);
+  vec3 G = P(-1, 1);
+  vec3 H = P( 0, 1);
+  vec3 I = P( 1, 1);
+
+  // blendResult Mapping: x|y|
+  //                      w|z|
+  ivec4 blendResult = ivec4(BLEND_NONE,BLEND_NONE,BLEND_NONE,BLEND_NONE);
+
+  // Preprocess corners
+  // Pixel Tap Mapping: -|-|-|-|-
+  //                    -|-|B|C|-
+  //                    -|D|E|F|x
+  //                    -|G|H|I|x
+  //                    -|-|x|x|-
+  if (!((eq(E,F) && eq(H,I)) || (eq(E,H) && eq(F,I))))
+  {
+    float dist_H_F = DistYCbCr(G, E) + DistYCbCr(E, C) + DistYCbCr(P(0,2), I) + DistYCbCr(I, P(2,0)) + (4.0 * DistYCbCr(H, F));
+    float dist_E_I = DistYCbCr(D, H) + DistYCbCr(H, P(1,2)) + DistYCbCr(B, F) + DistYCbCr(F, P(2,1)) + (4.0 * DistYCbCr(E, I));
+    bool dominantGradient = (DOMINANT_DIRECTION_THRESHOLD * dist_H_F) < dist_E_I;
+    blendResult.z = ((dist_H_F < dist_E_I) && neq(E,F) && neq(E,H)) ? ((dominantGradient) ? BLEND_DOMINANT : BLEND_NORMAL) : BLEND_NONE;
+  }
+
+
+  // Pixel Tap Mapping: -|-|-|-|-
+  //                    -|A|B|-|-
+  //                    x|D|E|F|-
+  //                    x|G|H|I|-
+  //                    -|x|x|-|-
+  if (!((eq(D,E) && eq(G,H)) || (eq(D,G) && eq(E,H))))
+  {
+    float dist_G_E = DistYCbCr(P(-2,1)  , D) + DistYCbCr(D, B) + DistYCbCr(P(-1,2), H) + DistYCbCr(H, F) + (4.0 * DistYCbCr(G, E));
+    float dist_D_H = DistYCbCr(P(-2,0)  , G) + DistYCbCr(G, P(0,2)) + DistYCbCr(A, E) + DistYCbCr(E, I) + (4.0 * DistYCbCr(D, H));
+    bool dominantGradient = (DOMINANT_DIRECTION_THRESHOLD * dist_D_H) < dist_G_E;
+    blendResult.w = ((dist_G_E > dist_D_H) && neq(E,D) && neq(E,H)) ? ((dominantGradient) ? BLEND_DOMINANT : BLEND_NORMAL) : BLEND_NONE;
+  }
+
+  // Pixel Tap Mapping: -|-|x|x|-
+  //                    -|A|B|C|x
+  //                    -|D|E|F|x
+  //                    -|-|H|I|-
+  //                    -|-|-|-|-
+  if (!((eq(B,C) && eq(E,F)) || (eq(B,E) && eq(C,F))))
+  {
+    float dist_E_C = DistYCbCr(D, B) + DistYCbCr(B, P(1,-2)) + DistYCbCr(H, F) + DistYCbCr(F, P(2,-1)) + (4.0 * DistYCbCr(E, C));
+    float dist_B_F = DistYCbCr(A, E) + DistYCbCr(E, I) + DistYCbCr(P(0,-2), C) + DistYCbCr(C, P(2,0)) + (4.0 * DistYCbCr(B, F));
+    bool dominantGradient = (DOMINANT_DIRECTION_THRESHOLD * dist_B_F) < dist_E_C;
+    blendResult.y = ((dist_E_C > dist_B_F) && neq(E,B) && neq(E,F)) ? ((dominantGradient) ? BLEND_DOMINANT : BLEND_NORMAL) : BLEND_NONE;
+  }
+
+  // Pixel Tap Mapping: -|x|x|-|-
+  //                    x|A|B|C|-
+  //                    x|D|E|F|-
+  //                    -|G|H|-|-
+  //                    -|-|-|-|-
+  if (!((eq(A,B) && eq(D,E)) || (eq(A,D) && eq(B,E))))
+  {
+    float dist_D_B = DistYCbCr(P(-2,0), A) + DistYCbCr(A, P(0,-2)) + DistYCbCr(G, E) + DistYCbCr(E, C) + (4.0 * DistYCbCr(D, B));
+    float dist_A_E = DistYCbCr(P(-2,-1), D) + DistYCbCr(D, H) + DistYCbCr(P(-1,-2), B) + DistYCbCr(B, F) + (4.0 * DistYCbCr(A, E));
+    bool dominantGradient = (DOMINANT_DIRECTION_THRESHOLD * dist_D_B) < dist_A_E;
+    blendResult.x = ((dist_D_B < dist_A_E) && neq(E,D) && neq(E,B)) ? ((dominantGradient) ? BLEND_DOMINANT : BLEND_NORMAL) : BLEND_NONE;
+  }
+
+  vec3 res = E;
+
+  // Pixel Tap Mapping: -|-|-|-|-
+  //                    -|-|B|C|-
+  //                    -|D|E|F|x
+  //                    -|G|H|I|x
+  //                    -|-|x|x|-
+  if(blendResult.z != BLEND_NONE)
+  {
+    float dist_F_G = DistYCbCr(F, G);
+    float dist_H_C = DistYCbCr(H, C);
+    bool doLineBlend = (blendResult.z == BLEND_DOMINANT ||
+                !((blendResult.y != BLEND_NONE && !IsPixEqual(E, G)) || (blendResult.w != BLEND_NONE && !IsPixEqual(E, C)) ||
+                  (IsPixEqual(G, H) && IsPixEqual(H, I) && IsPixEqual(I, F) && IsPixEqual(F, C) && !IsPixEqual(E, I))));
+
+    vec2 origin = vec2(0.0, 1.0 / sqrt(2.0));
+    vec2 direction = vec2(1.0, -1.0);
+    if(doLineBlend)
+    {
+      bool haveShallowLine = (STEEP_DIRECTION_THRESHOLD * dist_F_G <= dist_H_C) && neq(E,G) && neq(D,G);
+      bool haveSteepLine = (STEEP_DIRECTION_THRESHOLD * dist_H_C <= dist_F_G) && neq(E,C) && neq(B,C);
+      origin = haveShallowLine? vec2(0.0, 0.25) : vec2(0.0, 0.5);
+      direction.x += haveShallowLine? 1.0: 0.0;
+      direction.y -= haveSteepLine? 1.0: 0.0;
+    }
+
+    vec3 blendPix = mix(H,F, step(DistYCbCr(E, F), DistYCbCr(E, H)));
+    res = mix(res, blendPix, get_left_ratio(pos, origin, direction, scale));
+  }
+
+  // Pixel Tap Mapping: -|-|-|-|-
+  //                    -|A|B|-|-
+  //                    x|D|E|F|-
+  //                    x|G|H|I|-
+  //                    -|x|x|-|-
+  if(blendResult.w != BLEND_NONE)
+  {
+    float dist_H_A = DistYCbCr(H, A);
+    float dist_D_I = DistYCbCr(D, I);
+    bool doLineBlend = (blendResult.w == BLEND_DOMINANT ||
+                !((blendResult.z != BLEND_NONE && !IsPixEqual(E, A)) || (blendResult.x != BLEND_NONE && !IsPixEqual(E, I)) ||
+                  (IsPixEqual(A, D) && IsPixEqual(D, G) && IsPixEqual(G, H) && IsPixEqual(H, I) && !IsPixEqual(E, G))));
+
+    vec2 origin = vec2(-1.0 / sqrt(2.0), 0.0);
+    vec2 direction = vec2(1.0, 1.0);
+    if(doLineBlend)
+    {
+      bool haveShallowLine = (STEEP_DIRECTION_THRESHOLD * dist_H_A <= dist_D_I) && neq(E,A) && neq(B,A);
+      bool haveSteepLine  = (STEEP_DIRECTION_THRESHOLD * dist_D_I <= dist_H_A) && neq(E,I) && neq(F,I);
+      origin = haveShallowLine? vec2(-0.25, 0.0) : vec2(-0.5, 0.0);
+      direction.y += haveShallowLine? 1.0: 0.0;
+      direction.x += haveSteepLine? 1.0: 0.0;
+    }
+    origin = origin;
+    direction = direction;
+
+    vec3 blendPix = mix(H,D, step(DistYCbCr(E, D), DistYCbCr(E, H)));
+    res = mix(res, blendPix, get_left_ratio(pos, origin, direction, scale));
+  }
+
+  // Pixel Tap Mapping: -|-|x|x|-
+  //                    -|A|B|C|x
+  //                    -|D|E|F|x
+  //                    -|-|H|I|-
+  //                    -|-|-|-|-
+  if(blendResult.y != BLEND_NONE)
+  {
+    float dist_B_I = DistYCbCr(B, I);
+    float dist_F_A = DistYCbCr(F, A);
+    bool doLineBlend = (blendResult.y == BLEND_DOMINANT ||
+                !((blendResult.x != BLEND_NONE && !IsPixEqual(E, I)) || (blendResult.z != BLEND_NONE && !IsPixEqual(E, A)) ||
+                  (IsPixEqual(I, F) && IsPixEqual(F, C) && IsPixEqual(C, B) && IsPixEqual(B, A) && !IsPixEqual(E, C))));
+
+    vec2 origin = vec2(1.0 / sqrt(2.0), 0.0);
+    vec2 direction = vec2(-1.0, -1.0);
+
+    if(doLineBlend)
+    {
+      bool haveShallowLine = (STEEP_DIRECTION_THRESHOLD * dist_B_I <= dist_F_A) && neq(E,I) && neq(H,I);
+      bool haveSteepLine  = (STEEP_DIRECTION_THRESHOLD * dist_F_A <= dist_B_I) && neq(E,A) && neq(D,A);
+      origin = haveShallowLine? vec2(0.25, 0.0) : vec2(0.5, 0.0);
+      direction.y -= haveShallowLine? 1.0: 0.0;
+      direction.x -= haveSteepLine? 1.0: 0.0;
+    }
+
+    vec3 blendPix = mix(F,B, step(DistYCbCr(E, B), DistYCbCr(E, F)));
+    res = mix(res, blendPix, get_left_ratio(pos, origin, direction, scale));
+  }
+
+  // Pixel Tap Mapping: -|x|x|-|-
+  //                    x|A|B|C|-
+  //                    x|D|E|F|-
+  //                    -|G|H|-|-
+  //                    -|-|-|-|-
+  if(blendResult.x != BLEND_NONE)
+  {
+    float dist_D_C = DistYCbCr(D, C);
+    float dist_B_G = DistYCbCr(B, G);
+    bool doLineBlend = (blendResult.x == BLEND_DOMINANT ||
+                !((blendResult.w != BLEND_NONE && !IsPixEqual(E, C)) || (blendResult.y != BLEND_NONE && !IsPixEqual(E, G)) ||
+                  (IsPixEqual(C, B) && IsPixEqual(B, A) && IsPixEqual(A, D) && IsPixEqual(D, G) && !IsPixEqual(E, A))));
+
+    vec2 origin = vec2(0.0, -1.0 / sqrt(2.0));
+    vec2 direction = vec2(-1.0, 1.0);
+    if(doLineBlend)
+    {
+      bool haveShallowLine = (STEEP_DIRECTION_THRESHOLD * dist_D_C <= dist_B_G) && neq(E,C) && neq(F,C);
+      bool haveSteepLine  = (STEEP_DIRECTION_THRESHOLD * dist_B_G <= dist_D_C) && neq(E,G) && neq(H,G);
+      origin = haveShallowLine? vec2(0.0, -0.25) : vec2(0.0, -0.5);
+      direction.x -= haveShallowLine? 1.0: 0.0;
+      direction.y += haveSteepLine? 1.0: 0.0;
+    }
+
+    vec3 blendPix = mix(D,B, step(DistYCbCr(E, B), DistYCbCr(E, D)));
+    res = mix(res, blendPix, get_left_ratio(pos, origin, direction, scale));
+  }
+
+ 	gl_FragColor = vec4(res, 1.0);
+}
\ No newline at end of file