From c2545fd1618b9eeee10eb1e166730c2e79a9b18c Mon Sep 17 00:00:00 2001
From: Carter Anderson <mcanders1@gmail.com>
Date: Wed, 25 Mar 2020 19:20:52 -0700
Subject: [PATCH] RenderResourceSetId

---
 src/render/pipeline/bind_group.rs             |   8 +-
 .../render_resource_assignments.rs            | 114 +++++++++++++++++-
 2 files changed, 115 insertions(+), 7 deletions(-)

diff --git a/src/render/pipeline/bind_group.rs b/src/render/pipeline/bind_group.rs
index 8fc7a3625a..ce865ad9ea 100644
--- a/src/render/pipeline/bind_group.rs
+++ b/src/render/pipeline/bind_group.rs
@@ -16,11 +16,15 @@ pub struct BindGroupDescriptorId(u64);
 
 impl BindGroupDescriptor {
     pub fn new(index: u32, bindings: Vec<BindingDescriptor>) -> Self {
-        BindGroupDescriptor {
+        let mut descriptor = BindGroupDescriptor {
             index,
             bindings: bindings.iter().cloned().collect(),
             hash: None,
-        }
+        };
+
+        // TODO: remove all instances of get_or_update_id
+        descriptor.update_id();
+        descriptor
     }
 
     pub fn get_id(&self) -> Option<BindGroupDescriptorId> {
diff --git a/src/render/render_resource/render_resource_assignments.rs b/src/render/render_resource/render_resource_assignments.rs
index 41cdc1f1e3..e036cadf75 100644
--- a/src/render/render_resource/render_resource_assignments.rs
+++ b/src/render/render_resource/render_resource_assignments.rs
@@ -1,5 +1,9 @@
 use super::RenderResource;
-use std::collections::{HashMap, HashSet};
+use crate::render::pipeline::BindGroupDescriptor;
+use std::{
+    collections::{hash_map::DefaultHasher, HashMap, HashSet},
+    hash::{Hash, Hasher},
+};
 use uuid::Uuid;
 
 // PERF: if the assignments are scoped to a specific pipeline layout, then names could be replaced with indices here for a perf boost
@@ -22,17 +26,42 @@ impl RenderResourceAssignments {
         self.render_resources.insert(name.to_string(), resource);
     }
 
-    pub fn get_vertex_buffer(&self, name: &str) -> Option<(RenderResource, Option<RenderResource>)> {
+    pub fn get_vertex_buffer(
+        &self,
+        name: &str,
+    ) -> Option<(RenderResource, Option<RenderResource>)> {
         self.vertex_buffers.get(name).cloned()
     }
 
-    pub fn set_vertex_buffer(&mut self, name: &str, vertices_resource: RenderResource, indices_resource: Option<RenderResource>) {
-        self.vertex_buffers.insert(name.to_string(), (vertices_resource, indices_resource));
+    pub fn set_vertex_buffer(
+        &mut self,
+        name: &str,
+        vertices_resource: RenderResource,
+        indices_resource: Option<RenderResource>,
+    ) {
+        self.vertex_buffers
+            .insert(name.to_string(), (vertices_resource, indices_resource));
     }
 
     pub fn get_id(&self) -> RenderResourceAssignmentsId {
         self.id
     }
+
+    pub fn get_render_resource_set_id(
+        &self,
+        bind_group_descriptor: &BindGroupDescriptor,
+    ) -> Option<RenderResourceSetId> {
+        let mut hasher = DefaultHasher::new();
+        for binding_descriptor in bind_group_descriptor.bindings.iter() {
+            if let Some(render_resource) = self.get(&binding_descriptor.name) {
+                render_resource.hash(&mut hasher);
+            } else {
+                return None;
+            }
+        }
+
+        Some(RenderResourceSetId(hasher.finish()))
+    }
 }
 
 #[derive(Hash, Eq, PartialEq, Debug, Copy, Clone)]
@@ -42,4 +71,79 @@ impl Default for RenderResourceAssignmentsId {
     fn default() -> Self {
         RenderResourceAssignmentsId(Uuid::new_v4())
     }
-}
\ No newline at end of file
+}
+
+#[derive(Hash, Eq, PartialEq, Debug, Copy, Clone)]
+pub struct RenderResourceSetId(u64);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::render::pipeline::{
+        BindType, BindingDescriptor, UniformProperty, UniformPropertyType,
+    };
+
+    #[test]
+    fn test_render_resource_sets() {
+        let bind_group_descriptor = BindGroupDescriptor::new(
+            0,
+            vec![
+                BindingDescriptor {
+                    index: 0,
+                    name: "a".to_string(),
+                    bind_type: BindType::Uniform {
+                        dynamic: false,
+                        properties: vec![UniformProperty {
+                            name: "A".to_string(),
+                            property_type: UniformPropertyType::Struct(vec![
+                                UniformProperty {
+                                    name: "".to_string(),
+                                    property_type: UniformPropertyType::Mat4,
+                                }
+                            ]),
+                        }],
+                    },
+                },
+                BindingDescriptor {
+                    index: 1,
+                    name: "b".to_string(),
+                    bind_type: BindType::Uniform {
+                        dynamic: false,
+                        properties: vec![UniformProperty {
+                            name: "B".to_string(),
+                            property_type: UniformPropertyType::Float
+                        }],
+                    },
+                }
+            ],
+        );
+
+        let mut assignments = RenderResourceAssignments::default();
+        assignments.set("a", RenderResource(1));
+        assignments.set("b", RenderResource(2));
+
+        let mut different_assignments = RenderResourceAssignments::default();
+        different_assignments.set("a", RenderResource(3));
+        different_assignments.set("b", RenderResource(4));
+
+        let mut equal_assignments = RenderResourceAssignments::default();
+        equal_assignments.set("a", RenderResource(1));
+        equal_assignments.set("b", RenderResource(2));
+
+        let set_id = assignments.get_render_resource_set_id(&bind_group_descriptor);
+        assert_ne!(set_id, None);
+
+        let different_set_id = different_assignments.get_render_resource_set_id(&bind_group_descriptor);
+        assert_ne!(different_set_id, None);
+        assert_ne!(different_set_id, set_id);
+
+        let equal_set_id = equal_assignments.get_render_resource_set_id(&bind_group_descriptor);
+        assert_ne!(equal_set_id, None);
+        assert_eq!(equal_set_id, set_id);
+
+        let mut unmatched_assignments = RenderResourceAssignments::default();
+        unmatched_assignments.set("a", RenderResource(1));
+        let unmatched_set_id = unmatched_assignments.get_render_resource_set_id(&bind_group_descriptor);
+        assert_eq!(unmatched_set_id, None);
+    }
+}