Merge pull request #465 from KhronosGroup/fix-445

Overhaul Clip/CullDistance in GLSL and HLSL.

reference/opt/shaders-hlsl/frag/clip-cull-distance.frag

@@ -0,0 +1,30 @@
+static float gl_ClipDistance[2];
+static float gl_CullDistance[1];
+static float FragColor;
+
+struct SPIRV_Cross_Input
+{
+    float2 gl_ClipDistance0 : SV_ClipDistance0;
+    float gl_CullDistance0 : SV_CullDistance0;
+};
+
+struct SPIRV_Cross_Output
+{
+    float FragColor : SV_Target0;
+};
+
+void frag_main()
+{
+    FragColor = (gl_ClipDistance[0] + gl_CullDistance[0]) + gl_ClipDistance[1];
+}
+
+SPIRV_Cross_Output main(SPIRV_Cross_Input stage_input)
+{
+    gl_ClipDistance[0] = stage_input.gl_ClipDistance0.x;
+    gl_ClipDistance[1] = stage_input.gl_ClipDistance0.y;
+    gl_CullDistance[0] = stage_input.gl_CullDistance0.x;
+    frag_main();
+    SPIRV_Cross_Output stage_output;
+    stage_output.FragColor = FragColor;
+    return stage_output;
+}

reference/opt/shaders-hlsl/vert/clip-cull-distance.vert

@@ -0,0 +1,28 @@
+static float4 gl_Position;
+static float gl_ClipDistance[2];
+static float gl_CullDistance[1];
+struct SPIRV_Cross_Output
+{
+    float4 gl_Position : SV_Position;
+    float2 gl_ClipDistance0 : SV_ClipDistance0;
+    float gl_CullDistance0 : SV_CullDistance0;
+};
+
+void vert_main()
+{
+    gl_Position = 1.0f.xxxx;
+    gl_ClipDistance[0] = 0.0f;
+    gl_ClipDistance[1] = 0.0f;
+    gl_CullDistance[0] = 4.0f;
+}
+
+SPIRV_Cross_Output main()
+{
+    vert_main();
+    SPIRV_Cross_Output stage_output;
+    stage_output.gl_Position = gl_Position;
+    stage_output.gl_ClipDistance0.x = gl_ClipDistance[0];
+    stage_output.gl_ClipDistance0.y = gl_ClipDistance[1];
+    stage_output.gl_CullDistance0.x = gl_CullDistance[0];
+    return stage_output;
+}

reference/opt/shaders/desktop-only/frag/clip-cull-distance.desktop.frag

@@ -0,0 +1,12 @@
+#version 450
+
+in float gl_ClipDistance[4];
+in float gl_CullDistance[3];
+
+layout(location = 0) out float FragColor;
+
+void main()
+{
+    FragColor = gl_ClipDistance[0] + gl_CullDistance[0];
+}
+

reference/opt/shaders/desktop-only/vert/clip-cull-distance.desktop.sso.vert

@@ -0,0 +1,20 @@
+#version 450
+
+out gl_PerVertex
+{
+    vec4 gl_Position;
+    float gl_PointSize;
+    float gl_ClipDistance[4];
+    float gl_CullDistance[3];
+};
+
+void main()
+{
+    gl_Position = vec4(1.0);
+    gl_ClipDistance[0] = 0.0;
+    gl_ClipDistance[1] = 0.0;
+    gl_ClipDistance[2] = 0.0;
+    gl_ClipDistance[3] = 0.0;
+    gl_CullDistance[1] = 4.0;
+}
+

reference/opt/shaders/desktop-only/vert/clip-cull-distance.desktop.vert

@@ -1,11 +1,15 @@
 #version 450
 
+out float gl_ClipDistance[4];
+out float gl_CullDistance[3];
+
 void main()
 {
-    gl_Position = vec4(10.0);
-    gl_ClipDistance[0] = 1.0;
-    gl_ClipDistance[1] = 4.0;
-    gl_CullDistance[0] = 4.0;
-    gl_CullDistance[1] = 9.0;
+    gl_Position = vec4(1.0);
+    gl_ClipDistance[0] = 0.0;
+    gl_ClipDistance[1] = 0.0;
+    gl_ClipDistance[2] = 0.0;
+    gl_ClipDistance[3] = 0.0;
+    gl_CullDistance[1] = 4.0;
 }
 

reference/shaders-hlsl/frag/clip-cull-distance.frag

@@ -0,0 +1,30 @@
+static float gl_ClipDistance[2];
+static float gl_CullDistance[1];
+static float FragColor;
+
+struct SPIRV_Cross_Input
+{
+    float2 gl_ClipDistance0 : SV_ClipDistance0;
+    float gl_CullDistance0 : SV_CullDistance0;
+};
+
+struct SPIRV_Cross_Output
+{
+    float FragColor : SV_Target0;
+};
+
+void frag_main()
+{
+    FragColor = (gl_ClipDistance[0] + gl_CullDistance[0]) + gl_ClipDistance[1];
+}
+
+SPIRV_Cross_Output main(SPIRV_Cross_Input stage_input)
+{
+    gl_ClipDistance[0] = stage_input.gl_ClipDistance0.x;
+    gl_ClipDistance[1] = stage_input.gl_ClipDistance0.y;
+    gl_CullDistance[0] = stage_input.gl_CullDistance0.x;
+    frag_main();
+    SPIRV_Cross_Output stage_output;
+    stage_output.FragColor = FragColor;
+    return stage_output;
+}

reference/shaders-hlsl/vert/clip-cull-distance.vert

@@ -0,0 +1,28 @@
+static float4 gl_Position;
+static float gl_ClipDistance[2];
+static float gl_CullDistance[1];
+struct SPIRV_Cross_Output
+{
+    float4 gl_Position : SV_Position;
+    float2 gl_ClipDistance0 : SV_ClipDistance0;
+    float gl_CullDistance0 : SV_CullDistance0;
+};
+
+void vert_main()
+{
+    gl_Position = 1.0f.xxxx;
+    gl_ClipDistance[0] = 0.0f;
+    gl_ClipDistance[1] = 0.0f;
+    gl_CullDistance[0] = 4.0f;
+}
+
+SPIRV_Cross_Output main()
+{
+    vert_main();
+    SPIRV_Cross_Output stage_output;
+    stage_output.gl_Position = gl_Position;
+    stage_output.gl_ClipDistance0.x = gl_ClipDistance[0];
+    stage_output.gl_ClipDistance0.y = gl_ClipDistance[1];
+    stage_output.gl_CullDistance0.x = gl_CullDistance[0];
+    return stage_output;
+}

reference/shaders/desktop-only/frag/clip-cull-distance.desktop.frag

@@ -0,0 +1,12 @@
+#version 450
+
+in float gl_ClipDistance[4];
+in float gl_CullDistance[3];
+
+layout(location = 0) out float FragColor;
+
+void main()
+{
+    FragColor = gl_ClipDistance[0] + gl_CullDistance[0];
+}
+

reference/shaders/desktop-only/vert/clip-cull-distance.desktop.sso.vert

@@ -0,0 +1,20 @@
+#version 450
+
+out gl_PerVertex
+{
+    vec4 gl_Position;
+    float gl_PointSize;
+    float gl_ClipDistance[4];
+    float gl_CullDistance[3];
+};
+
+void main()
+{
+    gl_Position = vec4(1.0);
+    gl_ClipDistance[0] = 0.0;
+    gl_ClipDistance[1] = 0.0;
+    gl_ClipDistance[2] = 0.0;
+    gl_ClipDistance[3] = 0.0;
+    gl_CullDistance[1] = 4.0;
+}
+

reference/shaders/desktop-only/vert/clip-cull-distance.desktop.vert

@@ -1,11 +1,15 @@
 #version 450
 
+out float gl_ClipDistance[4];
+out float gl_CullDistance[3];
+
 void main()
 {
-    gl_Position = vec4(10.0);
-    gl_ClipDistance[0] = 1.0;
-    gl_ClipDistance[1] = 4.0;
-    gl_CullDistance[0] = 4.0;
-    gl_CullDistance[1] = 9.0;
+    gl_Position = vec4(1.0);
+    gl_ClipDistance[0] = 0.0;
+    gl_ClipDistance[1] = 0.0;
+    gl_ClipDistance[2] = 0.0;
+    gl_ClipDistance[3] = 0.0;
+    gl_CullDistance[1] = 4.0;
 }
 

shaders-hlsl/frag/clip-cull-distance.frag

@@ -0,0 +1,12 @@
+#version 450
+
+in float gl_ClipDistance[2];
+in float gl_CullDistance[1];
+
+layout(location = 0) out float FragColor;
+
+void main()
+{
+	FragColor = gl_ClipDistance[0] + gl_CullDistance[0] + gl_ClipDistance[1];
+}
+

shaders-hlsl/vert/clip-cull-distance.vert

@@ -0,0 +1,11 @@
+#version 450
+out float gl_ClipDistance[2];
+out float gl_CullDistance[1];
+
+void main()
+{
+	gl_Position = vec4(1.0);
+	gl_ClipDistance[0] = 0.0;
+	gl_ClipDistance[1] = 0.0;
+	gl_CullDistance[0] = 4.0;
+}

shaders/desktop-only/frag/clip-cull-distance.desktop.frag

@@ -0,0 +1,12 @@
+#version 450
+
+in float gl_ClipDistance[4];
+in float gl_CullDistance[3];
+
+layout(location = 0) out float FragColor;
+
+void main()
+{
+	FragColor = gl_ClipDistance[0] + gl_CullDistance[0];
+}
+

shaders/desktop-only/vert/clip-cull-distance.desktop.sso.vert

@@ -0,0 +1,13 @@
+#version 450
+out float gl_ClipDistance[4];
+out float gl_CullDistance[3];
+
+void main()
+{
+	gl_Position = vec4(1.0);
+	gl_ClipDistance[0] = 0.0;
+	gl_ClipDistance[1] = 0.0;
+	gl_ClipDistance[2] = 0.0;
+	gl_ClipDistance[3] = 0.0;
+	gl_CullDistance[1] = 4.0;
+}

shaders/desktop-only/vert/clip-cull-distance.desktop.vert

@@ -1,10 +1,13 @@
 #version 450
+out float gl_ClipDistance[4];
+out float gl_CullDistance[3];
 
 void main()
 {
-   gl_Position = vec4(10.0);
-   gl_ClipDistance[0] = 1.0;
-   gl_ClipDistance[1] = 4.0;
-   gl_CullDistance[0] = 4.0;
-   gl_CullDistance[1] = 9.0;
+	gl_Position = vec4(1.0);
+	gl_ClipDistance[0] = 0.0;
+	gl_ClipDistance[1] = 0.0;
+	gl_ClipDistance[2] = 0.0;
+	gl_ClipDistance[3] = 0.0;
+	gl_CullDistance[1] = 4.0;
 }

spirv_cross.cpp

@@ -3749,6 +3749,30 @@ bool Compiler::get_common_basic_type(const SPIRType &type, SPIRType::BaseType &b
 	}
 }
 
+void Compiler::ActiveBuiltinHandler::handle_builtin(const SPIRType &type, BuiltIn builtin)
+{
+	// If used, we will need to explicitly declare a new array size for these builtins.
+
+	if (builtin == BuiltInClipDistance)
+	{
+		if (!type.array_size_literal[0])
+			SPIRV_CROSS_THROW("Array size for ClipDistance must be a literal.");
+		uint32_t array_size = type.array[0];
+		if (array_size == 0)
+			SPIRV_CROSS_THROW("Array size for ClipDistance must not be unsized.");
+		compiler.clip_distance_count = array_size;
+	}
+	else if (builtin == BuiltInCullDistance)
+	{
+		if (!type.array_size_literal[0])
+			SPIRV_CROSS_THROW("Array size for CullDistance must be a literal.");
+		uint32_t array_size = type.array[0];
+		if (array_size == 0)
+			SPIRV_CROSS_THROW("Array size for CullDistance must not be unsized.");
+		compiler.cull_distance_count = array_size;
+	}
+}
+
 bool Compiler::ActiveBuiltinHandler::handle(spv::Op opcode, const uint32_t *args, uint32_t length)
 {
 	const auto add_if_builtin = [&](uint32_t id) {
@@ -3761,6 +3785,7 @@ bool Compiler::ActiveBuiltinHandler::handle(spv::Op opcode, const uint32_t *args
 			auto &flags =
 			    type.storage == StorageClassInput ? compiler.active_input_builtins : compiler.active_output_builtins;
 			flags |= 1ull << compiler.meta[id].decoration.builtin_type;
+			handle_builtin(type, compiler.meta[id].decoration.builtin_type);
 		}
 	};
 
@@ -3846,7 +3871,10 @@ bool Compiler::ActiveBuiltinHandler::handle(spv::Op opcode, const uint32_t *args
 				{
 					auto &decorations = compiler.meta[type->self].members[index];
 					if (decorations.builtin)
+					{
 						flags |= 1ull << decorations.builtin_type;
+						handle_builtin(compiler.get<SPIRType>(type->member_types[index]), decorations.builtin_type);
+					}
 				}
 
 				type = &compiler.get<SPIRType>(type->member_types[index]);
@@ -3871,6 +3899,8 @@ void Compiler::update_active_builtins()
 {
 	active_input_builtins = 0;
 	active_output_builtins = 0;
+	cull_distance_count = 0;
+	clip_distance_count = 0;
 	ActiveBuiltinHandler handler(*this);
 	traverse_all_reachable_opcodes(get<SPIRFunction>(entry_point), handler);
 }

spirv_cross.hpp

@@ -715,6 +715,8 @@ protected:
 
 		bool handle(spv::Op opcode, const uint32_t *args, uint32_t length) override;
 		Compiler &compiler;
+
+		void handle_builtin(const SPIRType &type, spv::BuiltIn builtin);
 	};
 
 	bool traverse_all_reachable_opcodes(const SPIRBlock &block, OpcodeHandler &handler) const;
@@ -735,6 +737,9 @@ protected:
 
 	uint64_t active_input_builtins = 0;
 	uint64_t active_output_builtins = 0;
+	uint32_t clip_distance_count = 0;
+	uint32_t cull_distance_count = 0;
+
 	// Traverses all reachable opcodes and sets active_builtins to a bitmask of all builtin variables which are accessed in the shader.
 	void update_active_builtins();
 	bool has_active_builtin(spv::BuiltIn builtin, spv::StorageClass storage);

spirv_glsl.cpp

@@ -1871,9 +1871,9 @@ void CompilerGLSL::emit_declared_builtin_block(StorageClass storage, ExecutionMo
 	if (emitted_builtins & (1ull << BuiltInPointSize))
 		statement("float gl_PointSize;");
 	if (emitted_builtins & (1ull << BuiltInClipDistance))
-		statement("float gl_ClipDistance[];"); // TODO: Do we need a fixed array size here?
+		statement("float gl_ClipDistance[", clip_distance_count, "];");
 	if (emitted_builtins & (1ull << BuiltInCullDistance))
-		statement("float gl_CullDistance[];"); // TODO: Do we need a fixed array size here?
+		statement("float gl_CullDistance[", cull_distance_count, "];");
 
 	bool tessellation = model == ExecutionModelTessellationEvaluation || model == ExecutionModelTessellationControl;
 	if (builtin_array)
@@ -1927,7 +1927,7 @@ void CompilerGLSL::emit_resources()
 		emit_pls();
 
 	// Emit custom gl_PerVertex for SSO compatibility.
-	if (options.separate_shader_objects && !options.es)
+	if (options.separate_shader_objects && !options.es && execution.model != ExecutionModelFragment)
 	{
 		switch (execution.model)
 		{
@@ -1946,6 +1946,18 @@ void CompilerGLSL::emit_resources()
 			break;
 		}
 	}
+	else
+	{
+		// Need to redeclare clip/cull distance with explicit size to use them.
+		// SPIR-V mandates these builtins have a size declared.
+		const char *storage = execution.model == ExecutionModelFragment ? "in" : "out";
+		if (clip_distance_count != 0)
+			statement(storage, " float gl_ClipDistance[", clip_distance_count, "];");
+		if (cull_distance_count != 0)
+			statement(storage, " float gl_CullDistance[", cull_distance_count, "];");
+		if (clip_distance_count != 0 || cull_distance_count != 0)
+			statement("");
+	}
 
 	bool emitted = false;
 

spirv_hlsl.cpp

@@ -509,6 +509,40 @@ void CompilerHLSL::emit_builtin_outputs_in_struct()
 			semantic = legacy ? "DEPTH" : "SV_Depth";
 			break;
 
+		case BuiltInClipDistance:
+			// HLSL is a bit weird here, use SV_ClipDistance0, SV_ClipDistance1 and so on with vectors.
+			for (uint32_t clip = 0; clip < clip_distance_count; clip += 4)
+			{
+				uint32_t to_declare = clip_distance_count - clip;
+				if (to_declare > 4)
+					to_declare = 4;
+
+				uint32_t semantic_index = clip / 4;
+
+				static const char *types[] = { "float", "float2", "float3", "float4" };
+				statement(types[to_declare - 1], " ",
+				          builtin_to_glsl(builtin, StorageClassOutput),
+				          semantic_index, " : SV_ClipDistance", semantic_index, ";");
+			}
+			break;
+
+		case BuiltInCullDistance:
+			// HLSL is a bit weird here, use SV_CullDistance0, SV_CullDistance1 and so on with vectors.
+			for (uint32_t cull = 0; cull < cull_distance_count; cull += 4)
+			{
+				uint32_t to_declare = cull_distance_count - cull;
+				if (to_declare > 4)
+					to_declare = 4;
+
+				uint32_t semantic_index = cull / 4;
+
+				static const char *types[] = { "float", "float2", "float3", "float4" };
+				statement(types[to_declare - 1], " ",
+				          builtin_to_glsl(builtin, StorageClassOutput),
+				          semantic_index, " : SV_CullDistance", semantic_index, ";");
+			}
+			break;
+
 		case BuiltInPointSize:
 			// If point_size_compat is enabled, just ignore PointSize.
 			// PointSize does not exist in HLSL, but some code bases might want to be able to use these shaders,
@@ -598,6 +632,40 @@ void CompilerHLSL::emit_builtin_inputs_in_struct()
 			// Handled specially.
 			break;
 
+		case BuiltInClipDistance:
+			// HLSL is a bit weird here, use SV_ClipDistance0, SV_ClipDistance1 and so on with vectors.
+			for (uint32_t clip = 0; clip < clip_distance_count; clip += 4)
+			{
+				uint32_t to_declare = clip_distance_count - clip;
+				if (to_declare > 4)
+					to_declare = 4;
+
+				uint32_t semantic_index = clip / 4;
+
+				static const char *types[] = { "float", "float2", "float3", "float4" };
+				statement(types[to_declare - 1], " ",
+				          builtin_to_glsl(builtin, StorageClassInput),
+				          semantic_index, " : SV_ClipDistance", semantic_index, ";");
+			}
+			break;
+
+		case BuiltInCullDistance:
+			// HLSL is a bit weird here, use SV_CullDistance0, SV_CullDistance1 and so on with vectors.
+			for (uint32_t cull = 0; cull < cull_distance_count; cull += 4)
+			{
+				uint32_t to_declare = cull_distance_count - cull;
+				if (to_declare > 4)
+					to_declare = 4;
+
+				uint32_t semantic_index = cull / 4;
+
+				static const char *types[] = { "float", "float2", "float3", "float4" };
+				statement(types[to_declare - 1], " ",
+				          builtin_to_glsl(builtin, StorageClassInput),
+				          semantic_index, " : SV_CullDistance", semantic_index, ";");
+			}
+			break;
+
 		default:
 			SPIRV_CROSS_THROW("Unsupported builtin in HLSL.");
 			break;
@@ -807,6 +875,7 @@ void CompilerHLSL::emit_builtin_variables()
 
 		const char *type = nullptr;
 		auto builtin = static_cast<BuiltIn>(i);
+		uint32_t array_size = 0;
 
 		switch (builtin)
 		{
@@ -855,6 +924,16 @@ void CompilerHLSL::emit_builtin_variables()
 			// Handled specially.
 			break;
 
+		case BuiltInClipDistance:
+			array_size = clip_distance_count;
+			type = "float";
+			break;
+
+		case BuiltInCullDistance:
+			array_size = cull_distance_count;
+			type = "float";
+			break;
+
 		default:
 			SPIRV_CROSS_THROW(join("Unsupported builtin in HLSL: ", unsigned(builtin)));
 			break;
@@ -865,8 +944,13 @@ void CompilerHLSL::emit_builtin_variables()
 		// need to distinguish that when we add support for that.
 
 		if (type)
+		{
+			if (array_size)
+				statement("static ", type, " ", builtin_to_glsl(builtin, storage), "[", array_size, "];");
+			else
 				statement("static ", type, " ", builtin_to_glsl(builtin, storage), ";");
 		}
+	}
 }
 
 void CompilerHLSL::emit_composite_constants()
@@ -1843,7 +1927,16 @@ void CompilerHLSL::emit_hlsl_entry_point()
 			break;
 
 		case BuiltInNumWorkgroups:
-			// Handled specially.
+			break;
+
+		case BuiltInClipDistance:
+			for (uint32_t clip = 0; clip < clip_distance_count; clip++)
+				statement("gl_ClipDistance[", clip, "] = stage_input.gl_ClipDistance", clip / 4, ".", "xyzw"[clip & 3], ";");
+			break;
+
+		case BuiltInCullDistance:
+			for (uint32_t cull = 0; cull < cull_distance_count; cull++)
+				statement("gl_CullDistance[", cull, "] = stage_input.gl_CullDistance", cull / 4, ".", "xyzw"[cull & 3], ";");
 			break;
 
 		default:
@@ -1938,8 +2031,25 @@ void CompilerHLSL::emit_hlsl_entry_point()
 			if (i == BuiltInPointSize)
 				continue;
 
-			auto builtin = builtin_to_glsl(static_cast<BuiltIn>(i), StorageClassOutput);
-			statement("stage_output.", builtin, " = ", builtin, ";");
+			switch (static_cast<BuiltIn>(i))
+			{
+			case BuiltInClipDistance:
+				for (uint32_t clip = 0; clip < clip_distance_count; clip++)
+					statement("stage_output.gl_ClipDistance", clip / 4, ".", "xyzw"[clip & 3], " = gl_ClipDistance[", clip, "];");
+				break;
+
+			case BuiltInCullDistance:
+				for (uint32_t cull = 0; cull < cull_distance_count; cull++)
+					statement("stage_output.gl_CullDistance", cull / 4, ".", "xyzw"[cull & 3], " = gl_CullDistance[", cull, "];");
+				break;
+
+			default:
+			{
+				auto builtin_expr = builtin_to_glsl(static_cast<BuiltIn>(i), StorageClassOutput);
+				statement("stage_output.", builtin_expr, " = ", builtin_expr, ";");
+				break;
+			}
+			}
 		}
 
 		for (auto &id : ids)