shader_unit: Intialize temporaries on shader invocation

src/video_core/pica/shader_unit.cpp

@@ -9,7 +9,10 @@
 
 namespace Pica {
 
-ShaderUnit::ShaderUnit(GeometryEmitter* emitter) : emitter_ptr{emitter} {}
+ShaderUnit::ShaderUnit(GeometryEmitter* emitter) : emitter_ptr{emitter} {
+    const Common::Vec4<f24> temp_vec{f24::Zero(), f24::Zero(), f24::Zero(), f24::One()};
+    temporary.fill(temp_vec);
+}
 
 ShaderUnit::~ShaderUnit() = default;
 

src/video_core/shader/generator/glsl_shader_gen.cpp

@@ -39,19 +39,6 @@ layout (binding = 1, std140) uniform vs_data {
     bool enable_clip1;
     vec4 clip_coef;
 };
-
-const vec2 EPSILON_Z = vec2(0.00000001f, -1.00001f);
-
-vec4 SanitizeVertex(vec4 vtx_pos) {
-    float ndc_z = vtx_pos.z / vtx_pos.w;
-    if (ndc_z > 0.f && ndc_z < EPSILON_Z[0]) {
-        vtx_pos.z = 0.f;
-    }
-    if (ndc_z < -1.f && ndc_z > EPSILON_Z[1]) {
-        vtx_pos.z = -vtx_pos.w;
-    }
-    return vtx_pos;
-}
 )";
 
 static std::string GetVertexInterfaceDeclaration(bool is_output, bool use_clip_planes,
@@ -107,7 +94,13 @@ std::string GenerateTrivialVertexShader(bool use_clip_planes, bool separable_sha
     out += GetVertexInterfaceDeclaration(true, use_clip_planes, separable_shader);
     out += VSUniformBlockDef;
 
+    // Certain games render 2D elements very close to clip plane 0 resulting in very tiny
+    // negative/positive z values when computing with f32 precision,
+    // causing some vertices to get erroneously clipped. To workaround this problem,
+    // we can use a very small epsilon value for clip plane comparison.
     out += R"(
+const float EPSILON_Z = 0.00000001f;
+
 void main() {
     primary_color = vert_color;
     texcoord0 = vert_texcoord0;
@@ -116,7 +109,10 @@ void main() {
     texcoord0_w = vert_texcoord0_w;
     normquat = vert_normquat;
     view = vert_view;
-    vec4 vtx_pos = SanitizeVertex(vert_position);
+    vec4 vtx_pos = vert_position;
+    if (abs(vtx_pos.z) < EPSILON_Z) {
+        vtx_pos.z = 0.f;
+    }
     gl_Position = vec4(vtx_pos.x, vtx_pos.y, -vtx_pos.z, vtx_pos.w);
 )";
     if (use_clip_planes) {
@@ -219,6 +215,7 @@ std::string GenerateVertexShader(const ShaderSetup& setup, const PicaVSConfig& c
             return "1.0";
         };
 
+        out += "const float EPSILON_Z = 0.00000001f;\n\n";
         out += "vec4 GetVertexQuaternion() {\n";
         out += "    return vec4(" + semantic(VSOutputAttributes::QUATERNION_X) + ", " +
                semantic(VSOutputAttributes::QUATERNION_Y) + ", " +
@@ -231,7 +228,9 @@ std::string GenerateVertexShader(const ShaderSetup& setup, const PicaVSConfig& c
                semantic(VSOutputAttributes::POSITION_Y) + ", " +
                semantic(VSOutputAttributes::POSITION_Z) + ", " +
                semantic(VSOutputAttributes::POSITION_W) + ");\n";
-        out += "    vtx_pos = SanitizeVertex(vtx_pos);\n";
+        out += "    if (abs(vtx_pos.z) < EPSILON_Z) {\n";
+        out += "        vtx_pos.z = 0.f;\n";
+        out += "    }\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
@@ -313,6 +312,7 @@ struct Vertex {
         return "1.0";
     };
 
+    out += "const float EPSILON_Z = 0.00000001f;\n\n";
     out += "vec4 GetVertexQuaternion(Vertex vtx) {\n";
     out += "    return vec4(" + semantic(VSOutputAttributes::QUATERNION_X) + ", " +
            semantic(VSOutputAttributes::QUATERNION_Y) + ", " +
@@ -325,7 +325,9 @@ struct Vertex {
            semantic(VSOutputAttributes::POSITION_Y) + ", " +
            semantic(VSOutputAttributes::POSITION_Z) + ", " +
            semantic(VSOutputAttributes::POSITION_W) + ");\n";
-    out += "    vtx_pos = SanitizeVertex(vtx_pos);\n";
+    out += "    if (abs(vtx_pos.z) < EPSILON_Z) {\n";
+    out += "        vtx_pos.z = 0.f;\n";
+    out += "    }\n";
     out += "    gl_Position = vec4(vtx_pos.x, vtx_pos.y, -vtx_pos.z, vtx_pos.w);\n";
     if (state.use_clip_planes) {
         out += "    gl_ClipDistance[0] = -vtx_pos.z;\n"; // fixed PICA clipping plane z <= 0