rsx: Implement interpolation using barycentrics

rpcs3/Emu/RSX/Program/GLSLCommon.cpp

@@ -1,7 +1,9 @@
 #include "stdafx.h"
 #include "Utilities/StrFmt.h"
+#include "../Common/simple_array.hpp"
 
 #include "GLSLCommon.h"
+#include "RSXFragmentProgram.h"
 
 namespace program_common
 {
@@ -1140,4 +1142,103 @@ namespace glsl
 		"	uint flags;\n"
 		"};\n\n";
 	}
+
+	void insert_fragment_shader_inputs_block(
+		std::stringstream& OS,
+		const RSXFragmentProgram& prog,
+		const std::vector<ParamType>& params,
+		const two_sided_lighting_config& _2sided_lighting,
+		std::function<int(std::string_view)> varying_location)
+	{
+		struct _varying_register_config
+		{
+			int location;
+			std::string name;
+			std::string type;
+		};
+
+		rsx::simple_array<_varying_register_config> varying_list;
+
+		for (const ParamType& PT : params)
+		{
+			for (const ParamItem& PI : PT.items)
+			{
+				// ssa is defined in the program body and is not a varying type
+				if (PI.name == "ssa") continue;
+
+				const auto reg_location = varying_location(PI.name);
+				std::string var_name = PI.name;
+
+				if (var_name == "fogc")
+				{
+					var_name = "fog_c";
+				}
+				else if (prog.two_sided_lighting)
+				{
+					if (var_name == "diff_color")
+					{
+						var_name = "diff_color0";
+					}
+					else if (var_name == "spec_color")
+					{
+						var_name = "spec_color0";
+					}
+				}
+
+				varying_list.push_back({ reg_location, var_name, PT.type });
+			}
+		}
+
+		if (prog.two_sided_lighting)
+		{
+			if (_2sided_lighting.two_sided_color)
+			{
+				varying_list.push_back({ varying_location("diff_color1"), "diff_color1", "vec4" });
+			}
+
+			if (_2sided_lighting.two_sided_specular)
+			{
+				varying_list.push_back({ varying_location("spec_color1"), "spec_color1", "vec4" });
+			}
+		}
+
+		if (varying_list.empty())
+		{
+			return;
+		}
+
+		// Make the output a little nicer
+		varying_list.sort(FN(x.location < y.location));
+
+		if (!(prog.ctrl & RSX_SHADER_CONTROL_ATTRIBUTE_INTERPOLATION))
+		{
+			for (const auto& reg : varying_list)
+			{
+				OS << "layout(location=" << reg.location << ") in " << reg.type << " " << reg.name << ";\n";
+			}
+
+			return;
+		}
+
+		for (const auto& reg : varying_list)
+		{
+			OS << "layout(location=" << reg.location << ") pervertexNV in " << reg.type << " " << reg.name << "_raw[3];\n";
+		}
+
+		// Interpolate the input attributes manually.
+		// Matches AMD behavior where gl_BaryCoordSmoothAMD only provides x and y with z being autogenerated.
+		OS <<
+		"vec4 _interpolate_varying3(const in vec4[3] v)\n"
+		"{\n"
+		"	const BaryCoord_z = 1.0 - (gl_BaryCoordNV.x + gl_BaryCoordNV.y);\n"
+		"	return gl_BaryCoordNV.x * v[0] + gl_BaryCoordNV.y * v[1] + BaryCoord_z * v[2];\n"
+		"}\n\n";
+
+		for (const auto& reg : varying_list)
+		{
+			OS << "vec4 " << reg.name << " = _interpolate_varying3(" << reg.name << "_raw);\n";
+		}
+
+		OS << "\n";
+	}
 }