Overhaul clip/cull distance support in GLSL.

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/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/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;