GLSL: Emit num_views for OVR_multiview2.

CMakeLists.txt

@@ -332,7 +332,7 @@ if (SPIRV_CROSS_STATIC)
 endif()
 
 set(spirv-cross-abi-major 0)
-set(spirv-cross-abi-minor 47)
+set(spirv-cross-abi-minor 48)
 set(spirv-cross-abi-patch 0)
 
 if (SPIRV_CROSS_SHARED)

main.cpp

@@ -662,6 +662,7 @@ struct CLIArguments
 	bool glsl_emit_push_constant_as_ubo = false;
 	bool glsl_emit_ubo_as_plain_uniforms = false;
 	bool glsl_force_flattened_io_blocks = false;
+	uint32_t glsl_ovr_multiview_view_count = 0;
 	SmallVector<pair<uint32_t, uint32_t>> glsl_ext_framebuffer_fetch;
 	bool glsl_ext_framebuffer_fetch_noncoherent = false;
 	bool vulkan_glsl_disable_ext_samplerless_texture_functions = false;
@@ -779,6 +780,7 @@ static void print_help_glsl()
 	                "\t[--remap-variable-type <variable_name> <new_variable_type>]:\n\t\tRemaps a variable type based on name.\n"
 	                "\t\tPrimary use case is supporting external samplers in ESSL for video rendering on Android where you could remap a texture to a YUV one.\n"
 	                "\t[--glsl-force-flattened-io-blocks]:\n\t\tAlways flatten I/O blocks and structs.\n"
+	                "\t[--glsl-ovr-multiview-view-count count]:\n\t\tIn GL_OVR_multiview2, specify layout(num_views).\n"
 	);
 	// clang-format on
 }
@@ -1280,6 +1282,7 @@ static string compile_iteration(const CLIArguments &args, std::vector<uint32_t>
 	opts.emit_push_constant_as_uniform_buffer = args.glsl_emit_push_constant_as_ubo;
 	opts.emit_uniform_buffer_as_plain_uniforms = args.glsl_emit_ubo_as_plain_uniforms;
 	opts.force_flattened_io_blocks = args.glsl_force_flattened_io_blocks;
+	opts.ovr_multiview_view_count = args.glsl_ovr_multiview_view_count;
 	opts.emit_line_directives = args.emit_line_directives;
 	opts.enable_storage_image_qualifier_deduction = args.enable_storage_image_qualifier_deduction;
 	opts.force_zero_initialized_variables = args.force_zero_initialized_variables;
@@ -1471,6 +1474,7 @@ static int main_inner(int argc, char *argv[])
 	cbs.add("--glsl-emit-push-constant-as-ubo", [&args](CLIParser &) { args.glsl_emit_push_constant_as_ubo = true; });
 	cbs.add("--glsl-emit-ubo-as-plain-uniforms", [&args](CLIParser &) { args.glsl_emit_ubo_as_plain_uniforms = true; });
 	cbs.add("--glsl-force-flattened-io-blocks", [&args](CLIParser &) { args.glsl_force_flattened_io_blocks = true; });
+	cbs.add("--glsl-ovr-multiview-view-count", [&args](CLIParser &parser) { args.glsl_ovr_multiview_view_count = parser.next_uint(); });
 	cbs.add("--glsl-remap-ext-framebuffer-fetch", [&args](CLIParser &parser) {
 		uint32_t input_index = parser.next_uint();
 		uint32_t color_attachment = parser.next_uint();

spirv_cross_c.cpp

@@ -472,6 +472,9 @@ spvc_result spvc_compiler_options_set_uint(spvc_compiler_options options, spvc_c
 	case SPVC_COMPILER_OPTION_GLSL_FORCE_FLATTENED_IO_BLOCKS:
 		options->glsl.force_flattened_io_blocks = value != 0;
 		break;
+	case SPVC_COMPILER_OPTION_GLSL_OVR_MULTIVIEW_VIEW_COUNT:
+		options->glsl.ovr_multiview_view_count = value;
+		break;
 #endif
 
 #if SPIRV_CROSS_C_API_HLSL

spirv_cross_c.h

@@ -40,7 +40,7 @@ extern "C" {
 /* Bumped if ABI or API breaks backwards compatibility. */
 #define SPVC_C_API_VERSION_MAJOR 0
 /* Bumped if APIs or enumerations are added in a backwards compatible way. */
-#define SPVC_C_API_VERSION_MINOR 47
+#define SPVC_C_API_VERSION_MINOR 48
 /* Bumped if internal implementation details change. */
 #define SPVC_C_API_VERSION_PATCH 0
 
@@ -675,6 +675,8 @@ typedef enum spvc_compiler_option
 	SPVC_COMPILER_OPTION_MSL_FORCE_SAMPLE_RATE_SHADING = 75 | SPVC_COMPILER_OPTION_MSL_BIT,
 	SPVC_COMPILER_OPTION_MSL_IOS_SUPPORT_BASE_VERTEX_INSTANCE = 76 | SPVC_COMPILER_OPTION_MSL_BIT,
 
+	SPVC_COMPILER_OPTION_GLSL_OVR_MULTIVIEW_VIEW_COUNT = 77 | SPVC_COMPILER_OPTION_GLSL_BIT,
+
 	SPVC_COMPILER_OPTION_INT_MAX = 0x7fffffff
 } spvc_compiler_option;
 

spirv_glsl.cpp

@@ -566,10 +566,32 @@ void CompilerGLSL::find_static_extensions()
 		case CapabilityVariablePointersStorageBuffer:
 			SPIRV_CROSS_THROW("VariablePointers capability is not supported in GLSL.");
 
+		case CapabilityMultiView:
+			if (options.vulkan_semantics)
+				require_extension_internal("GL_EXT_multiview");
+			else
+			{
+				require_extension_internal("GL_OVR_multiview2");
+				if (options.ovr_multiview_view_count == 0)
+					SPIRV_CROSS_THROW("ovr_multiview_view_count must be non-zero when using GL_OVR_multiview2.");
+				if (get_execution_model() != ExecutionModelVertex)
+					SPIRV_CROSS_THROW("OVR_multiview2 can only be used with Vertex shaders.");
+			}
+			break;
+
 		default:
 			break;
 		}
 	}
+
+	if (options.ovr_multiview_view_count)
+	{
+		if (options.vulkan_semantics)
+			SPIRV_CROSS_THROW("OVR_multiview2 cannot be used with Vulkan semantics.");
+		if (get_execution_model() != ExecutionModelVertex)
+			SPIRV_CROSS_THROW("OVR_multiview2 can only be used with Vertex shaders.");
+		require_extension_internal("GL_OVR_multiview2");
+	}
 }
 
 void CompilerGLSL::ray_tracing_khr_fixup_locations()
@@ -890,6 +912,10 @@ void CompilerGLSL::emit_header()
 
 	switch (execution.model)
 	{
+	case ExecutionModelVertex:
+		if (options.ovr_multiview_view_count)
+			inputs.push_back(join("num_views = ", options.ovr_multiview_view_count));
+		break;
 	case ExecutionModelGeometry:
 		if ((execution.flags.get(ExecutionModeInvocations)) && execution.invocations != 1)
 			inputs.push_back(join("invocations = ", execution.invocations));
@@ -8308,15 +8334,9 @@ string CompilerGLSL::builtin_to_glsl(BuiltIn builtin, StorageClass storage)
 
 	case BuiltInViewIndex:
 		if (options.vulkan_semantics)
-		{
-			require_extension_internal("GL_EXT_multiview");
 			return "gl_ViewIndex";
-		}
 		else
-		{
-			require_extension_internal("GL_OVR_multiview2");
 			return "gl_ViewID_OVR";
-		}
 
 	case BuiltInNumSubgroups:
 		request_subgroup_feature(ShaderSubgroupSupportHelper::NumSubgroups);

spirv_glsl.hpp

@@ -133,6 +133,9 @@ public:
 		// what happens on legacy GLSL targets for blocks and structs.
 		bool force_flattened_io_blocks = false;
 
+		// If non-zero, controls layout(num_views = N) in; in GL_OVR_multiview2.
+		uint32_t ovr_multiview_view_count = 0;
+
 		enum Precision
 		{
 			DontCare,