GLSL/HLSL: Add legacy handling for int vertex attributes

reference/opt/shaders-hlsl/vert/legacy-int-attribute.sm30.vert

@@ -0,0 +1,36 @@
+uniform float4 gl_HalfPixel;
+
+static float4 gl_Position;
+static int4 attr_int4;
+static int attr_int1;
+
+struct SPIRV_Cross_Input
+{
+    float4 attr_int4 : TEXCOORD0;
+    float attr_int1 : TEXCOORD1;
+};
+
+struct SPIRV_Cross_Output
+{
+    float4 gl_Position : POSITION;
+};
+
+void vert_main()
+{
+    gl_Position.x = float(attr_int4[attr_int1]);
+    gl_Position.y = 0.0f;
+    gl_Position.z = 0.0f;
+    gl_Position.w = 0.0f;
+    gl_Position.x = gl_Position.x - gl_HalfPixel.x * gl_Position.w;
+    gl_Position.y = gl_Position.y + gl_HalfPixel.y * gl_Position.w;
+}
+
+SPIRV_Cross_Output main(SPIRV_Cross_Input stage_input)
+{
+    attr_int4 = stage_input.attr_int4;
+    attr_int1 = stage_input.attr_int1;
+    vert_main();
+    SPIRV_Cross_Output stage_output;
+    stage_output.gl_Position = gl_Position;
+    return stage_output;
+}

reference/opt/shaders/legacy/vert/int-attribute.legacy.vert

@@ -0,0 +1,13 @@
+#version 100
+
+attribute vec4 attr_int4;
+attribute float attr_int1;
+
+void main()
+{
+    gl_Position.x = float(int(attr_int4[int(attr_int1)]));
+    gl_Position.y = 0.0;
+    gl_Position.z = 0.0;
+    gl_Position.w = 0.0;
+}
+

reference/shaders-hlsl/vert/legacy-int-attribute.sm30.vert

@@ -0,0 +1,36 @@
+uniform float4 gl_HalfPixel;
+
+static float4 gl_Position;
+static int4 attr_int4;
+static int attr_int1;
+
+struct SPIRV_Cross_Input
+{
+    float4 attr_int4 : TEXCOORD0;
+    float attr_int1 : TEXCOORD1;
+};
+
+struct SPIRV_Cross_Output
+{
+    float4 gl_Position : POSITION;
+};
+
+void vert_main()
+{
+    gl_Position.x = float(attr_int4[attr_int1]);
+    gl_Position.y = 0.0f;
+    gl_Position.z = 0.0f;
+    gl_Position.w = 0.0f;
+    gl_Position.x = gl_Position.x - gl_HalfPixel.x * gl_Position.w;
+    gl_Position.y = gl_Position.y + gl_HalfPixel.y * gl_Position.w;
+}
+
+SPIRV_Cross_Output main(SPIRV_Cross_Input stage_input)
+{
+    attr_int4 = stage_input.attr_int4;
+    attr_int1 = stage_input.attr_int1;
+    vert_main();
+    SPIRV_Cross_Output stage_output;
+    stage_output.gl_Position = gl_Position;
+    return stage_output;
+}

reference/shaders/legacy/vert/int-attribute.legacy.vert

@@ -0,0 +1,13 @@
+#version 100
+
+attribute vec4 attr_int4;
+attribute float attr_int1;
+
+void main()
+{
+    gl_Position.x = float(int(attr_int4[int(attr_int1)]));
+    gl_Position.y = 0.0;
+    gl_Position.z = 0.0;
+    gl_Position.w = 0.0;
+}
+

shaders-hlsl/vert/legacy-int-attribute.sm30.vert

@@ -0,0 +1,10 @@
+#version 310 es
+
+layout(location=0) in ivec4 attr_int4;
+layout(location=1) in int attr_int1;
+
+void main()
+{
+	gl_Position.x = float(attr_int4[attr_int1]);
+	gl_Position.yzw = vec3(0.0f, 0.0f, 0.0f);
+}

shaders/legacy/vert/int-attribute.legacy.vert

@@ -0,0 +1,10 @@
+#version 310 es
+
+layout(location=0) in ivec4 attr_int4;
+layout(location=1) in int attr_int1;
+
+void main()
+{
+	gl_Position.x = float(attr_int4[attr_int1]);
+	gl_Position.yzw = vec3(0.0f, 0.0f, 0.0f);
+}

spirv_glsl.cpp

@@ -2713,30 +2713,26 @@ void CompilerGLSL::emit_interface_block(const SPIRVariable &var)
 		{
 			add_resource_name(var.self);
 
-			// Tessellation control and evaluation shaders must have either gl_MaxPatchVertices or unsized arrays for input arrays.
+			// Legacy GLSL did not support int attributes, we automatically
+			// declare them as float and cast them on load/store
+			SPIRType newtype = type;
+			if (is_legacy() && var.storage == StorageClassInput && type.basetype == SPIRType::Int)
+				newtype.basetype = SPIRType::Float;
+
+			// Tessellation control and evaluation shaders must have either
+			// gl_MaxPatchVertices or unsized arrays for input arrays.
 			// Opt for unsized as it's the more "correct" variant to use.
-			bool control_point_input_array = type.storage == StorageClassInput && !type.array.empty() &&
+			if (type.storage == StorageClassInput && !type.array.empty() &&
 			    !has_decoration(var.self, DecorationPatch) &&
 			    (get_entry_point().model == ExecutionModelTessellationControl ||
-			                                  get_entry_point().model == ExecutionModelTessellationEvaluation);
-
-			uint32_t old_array_size = 0;
-			bool old_array_size_literal = true;
-
-			if (control_point_input_array)
+			     get_entry_point().model == ExecutionModelTessellationEvaluation))
 			{
-				swap(type.array.back(), old_array_size);
-				swap(type.array_size_literal.back(), old_array_size_literal);
+				newtype.array.back() = 0;
+				newtype.array_size_literal.back() = true;
 			}
 
 			statement(layout_for_variable(var), to_qualifiers_glsl(var.self),
-			          variable_decl(type, to_name(var.self), var.self), ";");
-
-			if (control_point_input_array)
-			{
-				swap(type.array.back(), old_array_size);
-				swap(type.array_size_literal.back(), old_array_size_literal);
-			}
+			          variable_decl(newtype, to_name(var.self), var.self), ";");
 		}
 	}
 }
@@ -16654,7 +16650,12 @@ void CompilerGLSL::cast_from_variable_load(uint32_t source_id, std::string &expr
 
 	// Only interested in standalone builtin variables.
 	if (!has_decoration(source_id, DecorationBuiltIn))
+	{
+		// Except for int attributes in legacy GLSL, which are cast from float.
+		if (is_legacy() && expr_type.basetype == SPIRType::Int && var && var->storage == StorageClassInput)
+			expr = join(type_to_glsl(expr_type), "(", expr, ")");
 		return;
+	}
 
 	auto builtin = static_cast<BuiltIn>(get_decoration(source_id, DecorationBuiltIn));
 	auto expected_type = expr_type.basetype;

spirv_hlsl.cpp

@@ -1016,6 +1016,7 @@ void CompilerHLSL::emit_interface_block_in_struct(const SPIRVariable &var, unord
 
 	string binding;
 	bool use_location_number = true;
+	bool need_matrix_unroll = false;
 	bool legacy = hlsl_options.shader_model <= 30;
 	if (execution.model == ExecutionModelFragment && var.storage == StorageClassOutput)
 	{
@@ -1031,6 +1032,12 @@ void CompilerHLSL::emit_interface_block_in_struct(const SPIRVariable &var, unord
 		if (legacy) // COLOR must be a four-component vector on legacy shader model targets (HLSL ERR_COLOR_4COMP)
 			type.vecsize = 4;
 	}
+	else if (var.storage == StorageClassInput && execution.model == ExecutionModelVertex)
+	{
+		need_matrix_unroll = true;
+		if (legacy) // Inputs must be floating-point in legacy targets.
+			type.basetype = SPIRType::Float;
+	}
 
 	const auto get_vacant_location = [&]() -> uint32_t {
 		for (uint32_t i = 0; i < 64; i++)
@@ -1039,8 +1046,6 @@ void CompilerHLSL::emit_interface_block_in_struct(const SPIRVariable &var, unord
 		SPIRV_CROSS_THROW("All locations from 0 to 63 are exhausted.");
 	};
 
-	bool need_matrix_unroll = var.storage == StorageClassInput && execution.model == ExecutionModelVertex;
-
 	auto name = to_name(var.self);
 	if (use_location_number)
 	{