Implement Reverse Interlaced 3D

src/citra/config.cpp

@@ -143,7 +143,8 @@ void Config::ReadValues() {
     std::string default_shader = "none (builtin)";
     if (Settings::values.render_3d == Settings::StereoRenderOption::Anaglyph)
         default_shader = "dubois (builtin)";
-    else if (Settings::values.render_3d == Settings::StereoRenderOption::Interlaced)
+    else if (Settings::values.render_3d == Settings::StereoRenderOption::Interlaced ||
+             Settings::values.render_3d == Settings::StereoRenderOption::ReverseInterlaced)
         default_shader = "horizontal (builtin)";
     Settings::values.pp_shader_name =
         sdl2_config->GetString("Renderer", "pp_shader_name", default_shader);

src/citra/default_ini.h

@@ -159,7 +159,7 @@ bg_blue =
 bg_green =
 
 # Whether and how Stereoscopic 3D should be rendered
-# 0 (default): Off, 1: Side by Side, 2: Anaglyph, 3: Interlaced
+# 0 (default): Off, 1: Side by Side, 2: Anaglyph, 3: Interlaced, 4: Reverse Interlaced
 render_3d =
 
 # Change 3D Intensity

src/citra_qt/configuration/configure_enhancements.cpp

@@ -85,7 +85,8 @@ void ConfigureEnhancements::updateShaders(Settings::StereoRenderOption stereo_op
 
     if (stereo_option == Settings::StereoRenderOption::Anaglyph)
         ui->shader_combobox->addItem(QStringLiteral("dubois (builtin)"));
-    else if (stereo_option == Settings::StereoRenderOption::Interlaced)
+    else if (stereo_option == Settings::StereoRenderOption::Interlaced ||
+             stereo_option == Settings::StereoRenderOption::ReverseInterlaced)
         ui->shader_combobox->addItem(QStringLiteral("horizontal (builtin)"));
     else
         ui->shader_combobox->addItem(QStringLiteral("none (builtin)"));

src/citra_qt/configuration/configure_enhancements.ui

@@ -171,6 +171,11 @@
             <string>Interlaced</string>
            </property>
           </item>
+          <item>
+           <property name="text">
+            <string>Reverse Interlaced</string>
+           </property>
+          </item>
          </widget>
         </item>
        </layout>

src/core/settings.h

@@ -32,7 +32,7 @@ enum class MicInputType {
     Static,
 };
 
-enum class StereoRenderOption { Off, SideBySide, Anaglyph, Interlaced };
+enum class StereoRenderOption { Off, SideBySide, Anaglyph, Interlaced, ReverseInterlaced };
 
 namespace NativeButton {
 enum Values {

src/video_core/renderer_opengl/renderer_opengl.cpp

@@ -311,6 +311,25 @@ void main() {
 }
 )";
 
+static const char fragment_shader_reverse_interlaced[] = R"(
+
+in vec2 frag_tex_coord;
+out vec4 color;
+
+uniform vec4 o_resolution;
+
+uniform sampler2D color_texture;
+uniform sampler2D color_texture_r;
+
+void main() {
+    float screen_row = o_resolution.x * frag_tex_coord.x;
+    if (int(screen_row) % 2 == 1)
+        color = texture(color_texture, frag_tex_coord);
+    else
+        color = texture(color_texture_r, frag_tex_coord);
+}
+)";
+
 /**
  * Vertex structure that the drawn screen rectangles are composed of.
  */
@@ -705,6 +724,19 @@ void RendererOpenGL::ReloadShader() {
                 shader_data += shader_text;
             }
         }
+    } else if (Settings::values.render_3d == Settings::StereoRenderOption::ReverseInterlaced) {
+        if (Settings::values.pp_shader_name == "horizontal (builtin)") {
+            shader_data += fragment_shader_reverse_interlaced;
+        } else {
+            std::string shader_text =
+                OpenGL::GetPostProcessingShaderCode(true, Settings::values.pp_shader_name);
+            if (shader_text.empty()) {
+                // Should probably provide some information that the shader couldn't load
+                shader_data += fragment_shader_reverse_interlaced;
+            } else {
+                shader_data += shader_text;
+            }
+        }
     } else {
         if (Settings::values.pp_shader_name == "none (builtin)") {
             shader_data += fragment_shader;
@@ -725,7 +757,8 @@ void RendererOpenGL::ReloadShader() {
     uniform_modelview_matrix = glGetUniformLocation(shader.handle, "modelview_matrix");
     uniform_color_texture = glGetUniformLocation(shader.handle, "color_texture");
     if (Settings::values.render_3d == Settings::StereoRenderOption::Anaglyph ||
-        Settings::values.render_3d == Settings::StereoRenderOption::Interlaced) {
+        Settings::values.render_3d == Settings::StereoRenderOption::Interlaced ||
+        Settings::values.render_3d == Settings::StereoRenderOption::ReverseInterlaced) {
         uniform_color_texture_r = glGetUniformLocation(shader.handle, "color_texture_r");
     }
     uniform_i_resolution = glGetUniformLocation(shader.handle, "i_resolution");
@@ -973,7 +1006,8 @@ void RendererOpenGL::DrawScreens(const Layout::FramebufferLayout& layout, bool f
 
     const bool stereo_single_screen =
         Settings::values.render_3d == Settings::StereoRenderOption::Anaglyph ||
-        Settings::values.render_3d == Settings::StereoRenderOption::Interlaced;
+        Settings::values.render_3d == Settings::StereoRenderOption::Interlaced ||
+        Settings::values.render_3d == Settings::StereoRenderOption::ReverseInterlaced;
 
     // Bind a second texture for the right eye if in Anaglyph mode
     if (stereo_single_screen) {