Add support for multi view extensions

src/back/glsl/features.rs

@@ -34,6 +34,7 @@ bitflags::bitflags! {
         const SAMPLE_VARIABLES = 1 << 15;
         /// Arrays with a dynamic length
         const DYNAMIC_ARRAY_SIZE = 1 << 16;
+        const MULTI_VIEW = 1 << 17;
     }
 }
 
@@ -101,6 +102,7 @@ impl FeaturesManager {
         check_feature!(CULL_DISTANCE, 450, 300);
         check_feature!(SAMPLE_VARIABLES, 400, 300);
         check_feature!(DYNAMIC_ARRAY_SIZE, 430, 310);
+        check_feature!(MULTI_VIEW, 140, 310);
 
         // Return an error if there are missing features
         if missing.is_empty() {
@@ -194,6 +196,16 @@ impl FeaturesManager {
             writeln!(out, "#extension GL_OES_sample_variables : require")?;
         }
 
+        if self.0.contains(Features::SAMPLE_VARIABLES) && version.is_es() {
+            // https://www.khronos.org/registry/OpenGL/extensions/OES/OES_sample_variables.txt
+            writeln!(out, "#extension GL_OES_sample_variables : require")?;
+        }
+
+        if self.0.contains(Features::MULTI_VIEW) {
+            // https://github.com/KhronosGroup/GLSL/blob/master/extensions/ext/GL_EXT_multiview.txt
+            writeln!(out, "#extension GL_EXT_multiview : require")?;
+        }
+
         Ok(())
     }
 }
@@ -372,6 +384,9 @@ impl<'a, W> Writer<'a, W> {
                             crate::BuiltIn::SampleIndex => {
                                 self.features.request(Features::SAMPLE_VARIABLES)
                             }
+                            crate::BuiltIn::ViewIndex => {
+                                self.features.request(Features::MULTI_VIEW)
+                            }
                             _ => {}
                         },
                         Binding::Location {

src/back/glsl/mod.rs

@@ -2625,6 +2625,7 @@ fn glsl_built_in(built_in: crate::BuiltIn, output: bool) -> &'static str {
                 "gl_FragCoord"
             }
         }
+        Bi::ViewIndex => "gl_ViewIndex",
         // vertex
         Bi::BaseInstance => "uint(gl_BaseInstance)",
         Bi::BaseVertex => "uint(gl_BaseVertex)",

src/back/hlsl/conv.rs

@@ -103,6 +103,9 @@ impl crate::BuiltIn {
             Self::BaseInstance | Self::BaseVertex | Self::WorkGroupSize => {
                 return Err(Error::Unimplemented(format!("builtin {:?}", self)))
             }
+            Self::ViewIndex => {
+                return Err(Error::Custom(format!("Unsupported builtin {:?}", self)))
+            }
         })
     }
 }

src/back/msl/mod.rs

@@ -358,7 +358,9 @@ impl ResolvedBinding {
                     Bi::WorkGroupId => "threadgroup_position_in_grid",
                     Bi::WorkGroupSize => "dispatch_threads_per_threadgroup",
                     Bi::NumWorkGroups => "threadgroups_per_grid",
-                    Bi::CullDistance => return Err(Error::UnsupportedBuiltIn(built_in)),
+                    Bi::CullDistance | Bi::ViewIndex => {
+                        return Err(Error::UnsupportedBuiltIn(built_in))
+                    }
                 };
                 write!(out, "{}", name)?;
             }

src/back/spv/writer.rs

@@ -1159,6 +1159,10 @@ impl Writer {
                             BuiltIn::FragCoord
                         }
                     }
+                    Bi::ViewIndex => {
+                        self.require_any("`view_index` built-in", &[spirv::Capability::MultiView])?;
+                        BuiltIn::ViewIndex
+                    }
                     // vertex
                     Bi::BaseInstance => BuiltIn::BaseInstance,
                     Bi::BaseVertex => BuiltIn::BaseVertex,
@@ -1284,6 +1288,19 @@ impl Writer {
         mod_info: &ModuleInfo,
         ep_index: Option<usize>,
     ) -> Result<(), Error> {
+        fn has_view_index_check(
+            ir_module: &crate::Module,
+            binding: Option<&crate::Binding>,
+            ty: Handle<crate::Type>,
+        ) -> bool {
+            match ir_module.types[ty].inner {
+                crate::TypeInner::Struct { ref members, .. } => members.iter().any(|member| {
+                    has_view_index_check(ir_module, member.binding.as_ref(), member.ty)
+                }),
+                _ => binding == Some(&crate::Binding::BuiltIn(crate::BuiltIn::ViewIndex)),
+            }
+        }
+
         let has_storage_buffers =
             ir_module
                 .global_variables
@@ -1292,11 +1309,21 @@ impl Writer {
                     crate::StorageClass::Storage { .. } => true,
                     _ => false,
                 });
+        let has_view_index = ir_module
+            .entry_points
+            .iter()
+            .flat_map(|entry| entry.function.arguments.iter())
+            .any(|arg| has_view_index_check(ir_module, arg.binding.as_ref(), arg.ty));
+
         if self.physical_layout.version < 0x10300 && has_storage_buffers {
             // enable the storage buffer class on < SPV-1.3
             Instruction::extension("SPV_KHR_storage_buffer_storage_class")
                 .to_words(&mut self.logical_layout.extensions);
         }
+        if has_view_index {
+            Instruction::extension("SPV_KHR_multiview")
+                .to_words(&mut self.logical_layout.extensions)
+        }
         Instruction::type_void(self.void_type).to_words(&mut self.logical_layout.declarations);
         Instruction::ext_inst_import(self.gl450_ext_inst_id, "GLSL.std.450")
             .to_words(&mut self.logical_layout.ext_inst_imports);

src/front/spv/convert.rs

@@ -121,6 +121,7 @@ pub(super) fn map_builtin(word: spirv::Word) -> Result<crate::BuiltIn, Error> {
     use spirv::BuiltIn as Bi;
     Ok(match spirv::BuiltIn::from_u32(word) {
         Some(Bi::Position) | Some(Bi::FragCoord) => crate::BuiltIn::Position,
+        Some(Bi::ViewIndex) => crate::BuiltIn::ViewIndex,
         // vertex
         Some(Bi::BaseInstance) => crate::BuiltIn::BaseInstance,
         Some(Bi::BaseVertex) => crate::BuiltIn::BaseVertex,

src/front/spv/mod.rs

@@ -75,6 +75,7 @@ pub const SUPPORTED_CAPABILITIES: &[spirv::Capability] = &[
 pub const SUPPORTED_EXTENSIONS: &[&str] = &[
     "SPV_KHR_storage_buffer_storage_class",
     "SPV_KHR_vulkan_memory_model",
+    "SPV_KHR_multiview",
 ];
 pub const SUPPORTED_EXT_SETS: &[&str] = &["GLSL.std.450"];
 

src/lib.rs

@@ -307,6 +307,7 @@ pub enum StorageClass {
 #[cfg_attr(feature = "deserialize", derive(Deserialize))]
 pub enum BuiltIn {
     Position,
+    ViewIndex,
     // vertex
     BaseInstance,
     BaseVertex,

src/valid/interface.rs

@@ -158,6 +158,17 @@ impl VaryingContext<'_> {
                                 width,
                             },
                     ),
+                    Bi::ViewIndex => (
+                        match self.stage {
+                            St::Vertex | St::Fragment => !self.output,
+                            St::Compute => false,
+                        },
+                        *ty_inner
+                            == Ti::Scalar {
+                                kind: Sk::Sint,
+                                width,
+                            },
+                    ),
                     Bi::FragDepth => (
                         self.stage == St::Fragment && self.output,
                         *ty_inner