Pass the vr_use_immersive_mode as a Vertex Shader Uniform

This means the same shaders can be used for both immersive and non-immersive as the uniform itself it the toggle in the GLSL rather than generating two different instances of the shader.
Furthermore, only one place where the gl_Position was being modified was actually needed; the other two seem to be able to be removed without it preventing immersive mode from working.

src/video_core/rasterizer_accelerated.cpp

@@ -4,6 +4,7 @@
 
 #include <limits>
 #include "common/alignment.h"
+#include "common/settings.h"
 #include "core/memory.h"
 #include "video_core/pica_state.h"
 #include "video_core/rasterizer_accelerated.h"
@@ -136,6 +137,7 @@ void RasterizerAccelerated::SyncEntireState() {
 
     // Sync uniforms
     SyncClipPlane();
+    SyncVRImmersive();
     SyncDepthScale();
     SyncDepthOffset();
     SyncAlphaTest();
@@ -860,4 +862,9 @@ void RasterizerAccelerated::SyncClipPlane() {
     }
 }
 
+void RasterizerAccelerated::SyncVRImmersive() {
+    vs_uniform_block_data.data.vr_use_immersive_mode = Settings::values.vr_use_immersive_mode.GetValue();
+    vs_uniform_block_data.dirty = true;
+}
+
 } // namespace VideoCore

src/video_core/rasterizer_accelerated.h

@@ -103,6 +103,9 @@ protected:
     /// Syncs the clip plane state to match the PICA register
     void SyncClipPlane();
 
+    /// Syncs the VR immersive flag
+    void SyncVRImmersive();
+
 protected:
     /// Structure that keeps tracks of the vertex shader uniform state
     struct VSUniformBlockData {

src/video_core/shader/generator/glsl_shader_gen.cpp

@@ -43,6 +43,7 @@ layout (set = 0, binding = 1, std140) uniform vs_data {
 #else
 layout (binding = 1, std140) uniform vs_data {
 #endif
+    bool vr_use_immersive_mode;
     bool enable_clip1;
     vec4 clip_coef;
 };
@@ -1681,12 +1682,7 @@ void main() {
     }
 )";
 
-    if (!Settings::values.vr_use_immersive_mode.GetValue())
-    {
-        out+= "\ngl_Position = vec4(vtx_pos.x, vtx_pos.y, -vtx_pos.z, vtx_pos.w);\n";
-    } else {
-        out+= "\ngl_Position = vec4(vtx_pos.x / 3.0, vtx_pos.y / 3.0, -vtx_pos.z, vtx_pos.w);\n";
-    }
+    out+= "\ngl_Position = vec4(vtx_pos.x, vtx_pos.y, -vtx_pos.z, vtx_pos.w);\n";
 
     if (use_clip_planes) {
         out += R"(
@@ -1807,14 +1803,7 @@ std::string GenerateVertexShader(const Pica::Shader::ShaderSetup& setup, const P
         out += "        vtx_pos.z = 0.f;\n";
         out += "    }\n";
 
-        if (!Settings::values.vr_use_immersive_mode.GetValue())
-        {
-              out+= "    gl_Position = vec4(vtx_pos.x, vtx_pos.y, -vtx_pos.z, vtx_pos.w);\n";
-        }
-        else
-        {
-              out+= "    gl_Position = vec4(vtx_pos.x / 3.0, vtx_pos.y / 3.0, -vtx_pos.z, vtx_pos.w);\n";
-        }
+        out+= "    gl_Position = vec4(vtx_pos.x, vtx_pos.y, -vtx_pos.z, vtx_pos.w);\n";
 
         if (config.state.use_clip_planes) {
             out += "    gl_ClipDistance[0] = -vtx_pos.z;\n"; // fixed PICA clipping plane z <= 0
@@ -1913,11 +1902,11 @@ struct Vertex {
     out += "        vtx_pos.z = 0.f;\n";
     out += "    }\n";
 
-    if (!Settings::values.vr_use_immersive_mode.GetValue()) {
-        out+= "    gl_Position = vec4(vtx_pos.x, vtx_pos.y, -vtx_pos.z, vtx_pos.w);\n";
-    } else {
-        out+= "    gl_Position = vec4(vtx_pos.x / 3.0, vtx_pos.y / 3.0, -vtx_pos.z, vtx_pos.w);\n";
-    }
+    out += "    if (vr_use_immersive_mode) {\n";
+    out += "        gl_Position = vec4(vtx_pos.x / 3.0, vtx_pos.y / 3.0, -vtx_pos.z, vtx_pos.w);\n";
+    out += "    } else {\n";
+    out += "        gl_Position = vec4(vtx_pos.x, vtx_pos.y, -vtx_pos.z, vtx_pos.w);\n";
+    out += "    }\n\n";
 
     if (state.use_clip_planes) {
         out += "    gl_ClipDistance[0] = -vtx_pos.z;\n"; // fixed PICA clipping plane z <= 0

src/video_core/shader/generator/shader_gen.cpp

@@ -21,8 +21,6 @@ PicaFSConfig::PicaFSConfig(const Pica::Regs& regs, bool has_fragment_shader_inte
                                      ? regs.framebuffer.output_merger.alpha_test.func.Value()
                                      : Pica::FramebufferRegs::CompareFunc::Always);
 
-    state.vr_use_immersive_mode.Assign(Settings::values.vr_use_immersive_mode.GetValue());
-
     state.texture0_type.Assign(regs.texturing.texture0.type);
 
     state.texture2_use_coord1.Assign(regs.texturing.main_config.texture2_use_coord1 != 0);
@@ -270,8 +268,6 @@ void PicaVSConfigState::Init(const Pica::Regs& regs, Pica::Shader::ShaderSetup&
     if (!use_geometry_shader_) {
         gs_state.Init(regs, use_clip_planes_);
     }
-
-    vr_use_immersive_mode = Settings::values.vr_use_immersive_mode.GetValue();
 }
 
 PicaVSConfig::PicaVSConfig(const Pica::Regs& regs, Pica::Shader::ShaderSetup& setup,

src/video_core/shader/generator/shader_gen.h

@@ -60,7 +60,6 @@ struct PicaFSConfigState {
         BitField<28, 1, u32> shadow_texture_orthographic;
         BitField<29, 1, u32> use_fragment_shader_interlock;
         BitField<30, 1, u32> use_custom_normal_map;
-        BitField<31, 1, u32> vr_use_immersive_mode;
     };
 
     union {
@@ -217,8 +216,6 @@ struct PicaVSConfigState {
 
     PicaGSConfigState gs_state;
 
-    bool vr_use_immersive_mode;
-
 };
 
 /**

src/video_core/shader/generator/shader_uniforms.h

@@ -89,6 +89,7 @@ struct PicaUniformsData {
 };
 
 struct VSUniformData {
+    bool vr_use_immersive_mode;
     bool enable_clip1;
     alignas(16) Common::Vec4f clip_coef;
 };