GPUShaderCreateInfo: Add explicit early_fragment_test

source/blender/gpu/intern/gpu_shader_create_info.cc

@@ -62,6 +62,10 @@ void ShaderCreateInfo::finalize()
     pass_resources_.extend(info.pass_resources_);
     typedef_sources_.extend_non_duplicates(info.typedef_sources_);
 
+    if (info.early_fragment_test_) {
+      early_fragment_test_ = true;
+    }
+
     validate(info);
 
     auto assert_no_overlap = [&](const bool test, const StringRefNull error) {

source/blender/gpu/intern/gpu_shader_create_info.hh

@@ -271,6 +271,8 @@ struct ShaderCreateInfo {
   bool finalized_ = false;
   /** If true, all resources will have an automatic location assigned. */
   bool auto_resource_location_ = false;
+  /** If true, force depth and stencil tests to always happen before fragment shader invocation. */
+  bool early_fragment_test_ = false;
   /**
    * Maximum length of all the resource names including each null terminator.
    * Only for names used by gpu::ShaderInterface.
@@ -521,6 +523,16 @@ struct ShaderCreateInfo {
     return *(Self *)this;
   }
 
+  /**
+   * Force fragment tests before fragment shader invocation.
+   * IMPORTANT: This is incompatible with using the gl_FragDepth output.
+   */
+  Self &early_fragment_test(bool enable)
+  {
+    early_fragment_test_ = enable;
+    return *(Self *)this;
+  }
+
   /**
    * Only needed if geometry shader is enabled.
    * IMPORTANT: Input and output instance name will have respectively "_in" and "_out" suffix

source/blender/gpu/opengl/gl_shader.cc

@@ -576,6 +576,9 @@ std::string GLShader::fragment_interface_declare(const ShaderCreateInfo &info) c
       pre_main += "  gpu_BaryCoordNoPersp = stable_bary_(gl_BaryCoordNoPerspAMD);\n";
     }
   }
+  if (info.early_fragment_test_) {
+    ss << "layout(early_fragment_tests) in;\n";
+  }
   ss << "\n/* Outputs. */\n";
   for (const ShaderCreateInfo::FragOut &output : info.fragment_outputs_) {
     ss << "layout(location = " << output.index;