video_core: Add MMPX texture filter (#6564)

* video_core: Add MMPX texture shader

* mmpx: Apply mix to mask alpha edge artifacting

* mmpx: Do not use deprecated texture fuction.

src/citra_qt/configuration/configure_enhancements.ui

@@ -199,6 +199,11 @@
              <string>xBRZ</string>
             </property>
            </item>
+            <item>
+              <property name="text">
+                <string>MMPX</string>
+              </property>
+            </item>
           </widget>
          </item>
         </layout>

src/common/settings.cpp

@@ -62,6 +62,8 @@ std::string_view GetTextureFilterName(TextureFilter filter) {
         return "ScaleForce";
     case TextureFilter::xBRZ:
         return "xBRZ";
+    case TextureFilter::MMPX:
+        return "MMPX";
     default:
         return "Invalid";
     }

src/common/settings.h

@@ -74,6 +74,7 @@ enum class TextureFilter : u32 {
     NearestNeighbor = 3,
     ScaleForce = 4,
     xBRZ = 5,
+    MMPX = 6
 };
 
 namespace NativeButton {

src/video_core/host_shaders/CMakeLists.txt

@@ -12,6 +12,7 @@ set(SHADER_FILES
     texture_filtering/scale_force.frag
     texture_filtering/tex_coord.vert
     texture_filtering/xbrz_freescale.frag
+    texture_filtering/mmpx.frag
     texture_filtering/x_gradient.frag
     texture_filtering/y_gradient.frag
     full_screen_triangle.vert

src/video_core/host_shaders/texture_filtering/mmpx.frag

@@ -0,0 +1,134 @@
+// Copyright 2023 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+//? #version 430 core
+precision mediump float;
+
+layout(location = 0) in vec2 tex_coord;
+layout(location = 0) out vec4 frag_color;
+layout(binding = 0) uniform sampler2D tex;
+
+vec2 source_size = vec2(textureSize(tex, 0));
+vec2 pos = fract(tex_coord * source_size) - vec2(0.5, 0.5);
+vec2 coord = tex_coord - pos / source_size;
+
+vec4 src(float x, float y)
+{
+    return texture(tex, coord + vec2(x, y) * 1 / source_size);
+}
+
+float luma(vec4 col){
+    return dot(col.rgb, vec3(0.2126, 0.7152, 0.0722)) * (1 - col.a);
+}
+
+bool same(vec4 B, vec4 A0){
+    return all(equal(B, A0));
+}
+
+bool notsame(vec4 B, vec4 A0){
+    return any(notEqual(B, A0));
+}
+
+bool all_eq2(vec4 B, vec4 A0, vec4 A1) {
+    return (same(B,A0) && same(B,A1));
+}
+
+bool all_eq3(vec4 B, vec4 A0, vec4 A1, vec4 A2) {
+    return (same(B,A0) && same(B,A1) && same(B,A2));
+}
+
+bool all_eq4(vec4 B, vec4 A0, vec4 A1, vec4 A2, vec4 A3) {
+    return (same(B,A0) && same(B,A1) && same(B,A2) && same(B,A3));
+}
+
+bool any_eq3(vec4 B, vec4 A0, vec4 A1, vec4 A2) {
+    return (same(B,A0) || same(B,A1) || same(B,A2));
+}
+
+bool none_eq2(vec4 B, vec4 A0, vec4 A1) {
+    return (notsame(B,A0) && notsame(B,A1));
+}
+
+bool none_eq4(vec4 B, vec4 A0, vec4 A1, vec4 A2, vec4 A3) {
+    return (notsame(B,A0) && notsame(B,A1) && notsame(B,A2) && notsame(B,A3));
+}
+
+void main()
+{
+    vec4 E = src(0.0,0.0);
+
+    vec4 A = src(-1.0,-1.0);
+    vec4 B = src(0.0,-1.0);
+    vec4 C = src(1.0,-1.0);
+
+    vec4 D = src(-1.0,0.0);
+    vec4 F = src(1.0,0.0);
+
+    vec4 G = src(-1.0,1.0);
+    vec4 H = src(0.0,1.0);
+    vec4 I = src(1.0,1.0);
+
+    vec4 J = E;
+    vec4 K = E;
+    vec4 L = E;
+    vec4 M = E;
+
+    frag_color = E;
+
+    if(same(E,A) && same(E,B) && same(E,C) && same(E,D) && same(E,F) && same(E,G) && same(E,H) && same(E,I)) return;
+
+    vec4 P  = src(0.0,2.0);
+    vec4 Q  = src(-2.0,0.0);
+    vec4 R  = src(2.0,0.0);
+    vec4 S  = src(0.0,2.0);
+
+    float Bl = luma(B);
+    float Dl = luma(D);
+    float El = luma(E);
+    float Fl = luma(F);
+    float Hl = luma(H);
+
+    if (((same(D,B) && notsame(D,H) && notsame(D,F))) && ((El>=Dl) || same(E,A)) && any_eq3(E,A,C,G) && ((El<Dl) || notsame(A,D) || notsame(E,P) || notsame(E,Q))) J=mix(D, J, 0.5);
+    if (((same(B,F) && notsame(B,D) && notsame(B,H))) && ((El>=Bl) || same(E,C)) && any_eq3(E,A,C,I) && ((El<Bl) || notsame(C,B) || notsame(E,P) || notsame(E,R))) K=mix(B, K, 0.5);
+    if (((same(H,D) && notsame(H,F) && notsame(H,B))) && ((El>=Hl) || same(E,G)) && any_eq3(E,A,G,I) && ((El<Hl) || notsame(G,H) || notsame(E,S) || notsame(E,Q))) L=mix(H, L, 0.5);
+    if (((same(F,H) && notsame(F,B) && notsame(F,D))) && ((El>=Fl) || same(E,I)) && any_eq3(E,C,G,I) && ((El<Fl) || notsame(I,H) || notsame(E,R) || notsame(E,S))) M=mix(F, M, 0.5);
+
+    if ((notsame(E,F) && all_eq4(E,C,I,D,Q) && all_eq2(F,B,H)) && notsame(F,src(3.0,0.0))) {M=mix(M, F, 0.5); K=mix(K, M, 0.5);};
+    if ((notsame(E,D) && all_eq4(E,A,G,F,R) && all_eq2(D,B,H)) && notsame(D,src(-3.0,0.0))) {L=mix(L, D, 0.5); J=mix(J, L, 0.5);};
+    if ((notsame(E,H) && all_eq4(E,G,I,B,P) && all_eq2(H,D,F)) && notsame(H,src(0.0,3.0))) {M=mix(M, H, 0.5); L=mix(L, M, 0.5);};
+    if ((notsame(E,B) && all_eq4(E,A,C,H,S) && all_eq2(B,D,F)) && notsame(B,src(0.0,-3.0))) {K=mix(K, B, 0.5); J=mix(J, K, 0.5);};
+
+    if ((Bl<El) && all_eq4(E,G,H,I,S) && none_eq4(E,A,D,C,F)) {K=mix(K, B, 0.5); J=mix(J, K, 0.5);}
+    if ((Hl<El) && all_eq4(E,A,B,C,P) && none_eq4(E,D,G,I,F)) {M=mix(M, H, 0.5); L=mix(L, M, 0.5);}
+    if ((Fl<El) && all_eq4(E,A,D,G,Q) && none_eq4(E,B,C,I,H)) {M=mix(M, F, 0.5); K=mix(K, M, 0.5);}
+    if ((Dl<El) && all_eq4(E,C,F,I,R) && none_eq4(E,B,A,G,H)) {L=mix(L, D, 0.5); J=mix(J, L, 0.5);}
+
+    if (notsame(H,B)) {
+        if (notsame(H,A) && notsame(H,E) && notsame(H,C)) {
+            if (all_eq3(H,G,F,R) && none_eq2(H,D,src(2.0,-1.0))) L=mix(M, L, 0.5);
+            if (all_eq3(H,I,D,Q) && none_eq2(H,F,src(-2.0,-1.0))) M=mix(L, M, 0.5);
+        }
+
+        if (notsame(B,I) && notsame(B,G) && notsame(B,E)) {
+            if (all_eq3(B,A,F,R) && none_eq2(B,D,src(2.0,1.0))) J=mix(K, L, 0.5);
+            if (all_eq3(B,C,D,Q) && none_eq2(B,F,src(-2.0,1.0))) K=mix(J, K, 0.5);
+        }
+    }
+
+    if (notsame(F,D)) {
+        if (notsame(D,I) && notsame(D,E) && notsame(D,C)) {
+            if (all_eq3(D,A,H,S) && none_eq2(D,B,src(1.0,2.0))) J=mix(L, J, 0.5);
+            if (all_eq3(D,G,B,P) && none_eq2(D,H,src(1.0,2.0))) L=mix(J, L, 0.5);
+        }
+
+        if (notsame(F,E) && notsame(F,A) && notsame(F,G)) {
+            if (all_eq3(F,C,H,S) && none_eq2(F,B,src(-1.0,2.0))) K=mix(M, K, 0.5);
+            if (all_eq3(F,I,B,P) && none_eq2(F,H,src(-1.0,-2.0))) M=mix(K, M, 0.5);
+        }
+    }
+
+    vec2 a = fract(tex_coord * source_size);
+    vec4 colour = (a.x < 0.5) ? (a.y < 0.5 ? J : L) : (a.y < 0.5 ? K : M);
+    frag_color = colour;
+}

src/video_core/renderer_opengl/gl_blit_helper.cpp

@@ -14,6 +14,7 @@
 #include "video_core/host_shaders/format_reinterpreter/rgba4_to_rgb5a1_frag.h"
 #include "video_core/host_shaders/full_screen_triangle_vert.h"
 #include "video_core/host_shaders/texture_filtering/bicubic_frag.h"
+#include "video_core/host_shaders/texture_filtering/mmpx_frag.h"
 #include "video_core/host_shaders/texture_filtering/nearest_neighbor_frag.h"
 #include "video_core/host_shaders/texture_filtering/refine_frag.h"
 #include "video_core/host_shaders/texture_filtering/scale_force_frag.h"
@@ -60,7 +61,8 @@ BlitHelper::BlitHelper(const Driver& driver_)
       nearest_program{CreateProgram(HostShaders::NEAREST_NEIGHBOR_FRAG)},
       scale_force_program{CreateProgram(HostShaders::SCALE_FORCE_FRAG)},
       xbrz_program{CreateProgram(HostShaders::XBRZ_FREESCALE_FRAG)},
-      gradient_x_program{CreateProgram(HostShaders::X_GRADIENT_FRAG)},
+      mmpx_program{CreateProgram(HostShaders::MMPX_FRAG)}, gradient_x_program{CreateProgram(
+                                                               HostShaders::X_GRADIENT_FRAG)},
       gradient_y_program{CreateProgram(HostShaders::Y_GRADIENT_FRAG)},
       refine_program{CreateProgram(HostShaders::REFINE_FRAG)},
       d24s8_to_rgba8{CreateProgram(HostShaders::D24S8_TO_RGBA8_FRAG)},
@@ -175,6 +177,9 @@ bool BlitHelper::Filter(Surface& surface, const VideoCore::TextureBlit& blit) {
     case TextureFilter::xBRZ:
         FilterXbrz(surface, blit);
         break;
+    case TextureFilter::MMPX:
+        FilterMMPX(surface, blit);
+        break;
     default:
         LOG_ERROR(Render_OpenGL, "Unknown texture filter {}", filter);
     }
@@ -270,6 +275,14 @@ void BlitHelper::FilterXbrz(Surface& surface, const VideoCore::TextureBlit& blit
     Draw(xbrz_program, surface.Handle(), draw_fbo.handle, blit.dst_level, blit.dst_rect);
 }
 
+void BlitHelper::FilterMMPX(Surface& surface, const VideoCore::TextureBlit& blit) {
+    const OpenGLState prev_state = OpenGLState::GetCurState();
+    SCOPE_EXIT({ prev_state.Apply(); });
+    state.texture_units[0].texture_2d = surface.Handle(0);
+    SetParams(mmpx_program, surface.RealExtent(false), blit.src_rect);
+    Draw(mmpx_program, surface.Handle(), draw_fbo.handle, blit.dst_level, blit.dst_rect);
+}
+
 void BlitHelper::SetParams(OGLProgram& program, const VideoCore::Extent& src_extent,
                            Common::Rectangle<u32> src_rect) {
     glProgramUniform2f(

src/video_core/renderer_opengl/gl_blit_helper.h

@@ -40,6 +40,8 @@ private:
 
     void FilterXbrz(Surface& surface, const VideoCore::TextureBlit& blit);
 
+    void FilterMMPX(Surface& surface, const VideoCore::TextureBlit& blit);
+
     void SetParams(OGLProgram& program, const VideoCore::Extent& src_extent,
                    Common::Rectangle<u32> src_rect);
 
@@ -58,6 +60,7 @@ private:
     OGLProgram nearest_program;
     OGLProgram scale_force_program;
     OGLProgram xbrz_program;
+    OGLProgram mmpx_program;
     OGLProgram gradient_x_program;
     OGLProgram gradient_y_program;
     OGLProgram refine_program;