glsl-out: push constants use anonymous uniforms

Previously this was done with UBOs but this posed some problems when
integrating with wgpu (see gfx-rs/wgpu#2400)

src/back/glsl/mod.rs

@@ -86,9 +86,7 @@ impl crate::AtomicFunction {
 impl crate::StorageClass {
  fn is_buffer(&self) -> bool {
  match *self {
- crate::StorageClass::PushConstant
- | crate::StorageClass::Uniform
- | crate::StorageClass::Storage { .. } => true,
+ crate::StorageClass::Uniform | crate::StorageClass::Storage { .. } => true,
  _ => false,
  }
  }
@@ -230,8 +228,6 @@ pub struct Options {
  pub writer_flags: WriterFlags,
  /// Map of resources association to binding locations.
  pub binding_map: BindingMap,
- /// The binding to give the push constant buffer if it's present
- pub push_constant_binding: u32,
 }
 
 impl Default for Options {
@@ -240,7 +236,6 @@ impl Default for Options {
  version: Version::Embedded(310),
  writer_flags: WriterFlags::ADJUST_COORDINATE_SPACE,
  binding_map: BindingMap::default(),
- push_constant_binding: 0,
  }
  }
 }
@@ -263,7 +258,6 @@ pub struct PipelineOptions {
 pub struct ReflectionInfo {
  pub texture_mapping: crate::FastHashMap<String, TextureMapping>,
  pub uniforms: crate::FastHashMap<Handle<crate::GlobalVariable>, String>,
- pub push_constant: Option<String>,
 }
 
 /// Structure that connects a texture to a sampler or not
@@ -894,13 +888,7 @@ impl<'a, W: Write> Writer<'a, W> {
  global: &crate::GlobalVariable,
  ) -> BackendResult {
  if self.options.version.supports_explicit_locations() {
- if let crate::StorageClass::PushConstant = global.class {
- write!(
- self.out,
- "layout(std140, binding = {}) ",
- self.options.push_constant_binding
- )?
- } else if let Some(ref br) = global.binding {
+ if let Some(ref br) = global.binding {
  match self.options.binding_map.get(br) {
  Some(binding) => {
  let layout = match global.class {
@@ -911,9 +899,7 @@ impl<'a, W: Write> Writer<'a, W> {
  "std140, "
  }
  }
- crate::StorageClass::Uniform | crate::StorageClass::PushConstant => {
- "std140, "
- }
+ crate::StorageClass::Uniform => "std140, ",
  _ => "",
  };
  write!(self.out, "layout({}binding = {}) ", layout, binding)?
@@ -977,6 +963,11 @@ impl<'a, W: Write> Writer<'a, W> {
  false
  };
 
+ if let crate::StorageClass::PushConstant = global.class {
+ let global_name = self.get_global_name(handle, global);
+ self.reflection_names_globals.insert(handle, global_name);
+ }
+
  // Finally write the global name and end the global with a `;` and a newline
  // Leading space is important
  write!(self.out, " ")?;
@@ -2878,7 +2869,6 @@ impl<'a, W: Write> Writer<'a, W> {
  let info = self.info.get_entry_point(self.entry_point_idx as usize);
  let mut texture_mapping = crate::FastHashMap::default();
  let mut uniforms = crate::FastHashMap::default();
- let mut push_constant = None;
 
  for sampling in info.sampling_set.iter() {
  let tex_name = self.reflection_names_globals[&sampling.image].clone();
@@ -2909,10 +2899,6 @@ impl<'a, W: Write> Writer<'a, W> {
  let name = self.reflection_names_globals[&handle].clone();
  uniforms.insert(handle, name);
  }
- crate::StorageClass::PushConstant => {
- let name = self.reflection_names_globals[&handle].clone();
- push_constant = Some(name)
- }
  _ => (),
  },
  crate::TypeInner::Image { .. } => {
@@ -2936,7 +2922,6 @@ impl<'a, W: Write> Writer<'a, W> {
  Ok(ReflectionInfo {
  texture_mapping,
  uniforms,
- push_constant,
  })
  }
 }

tests/in/functions-webgl.param.ron

@@ -3,6 +3,5 @@
  version: Embedded(300),
  writer_flags: (bits: 0),
  binding_map: {},
- push_constant_binding: 0,
  ),
 )

tests/in/interpolate.param.ron

@@ -10,6 +10,5 @@
  version: Desktop(400),
  writer_flags: (bits: 0),
  binding_map: {},
- push_constant_binding: 0,
  ),
 )

tests/in/push-constants.param.ron

@@ -4,6 +4,5 @@
  version: Embedded(320),
  writer_flags: (bits: 0),
  binding_map: {},
- push_constant_binding: 4,
  ),
 )

tests/in/quad.param.ron

@@ -8,6 +8,5 @@
  version: Embedded(300),
  writer_flags: (bits: 0),
  binding_map: {},
- push_constant_binding: 0,
  ),
 )

tests/in/skybox.param.ron

@@ -43,7 +43,6 @@
  (group: 0, binding: 0): 0,
  (group: 0, binding: 1): 0,
  },
- push_constant_binding: 0,
  ),
  hlsl: (
  shader_model: V5_1,

tests/out/glsl/push-constants.main.Fragment.glsl

@@ -9,7 +9,7 @@ struct PushConstants {
 struct FragmentIn {
  vec4 color;
 };
-layout(std140, binding = 4) uniform PushConstants_block_0Fragment { PushConstants pc; };
+uniform PushConstants pc;
 
 layout(location = 0) smooth in vec4 _vs2fs_location0;
 layout(location = 0) out vec4 _fs2p_location0;