More work on rendering

modules/graphics/src/materials.rs

@@ -80,6 +80,40 @@ impl Material {
     &self.shader
   }
 
+  /// Gets the flags of the material.
+  pub fn flags(&self) -> MaterialFlags {
+    let mut flags = MaterialFlags::empty();
+
+    let shader = &self.shader;
+    let metadata = shader.flags();
+
+    if self.blend_state() != BlendState::Disabled {
+      flags.insert(MaterialFlags::ALPHA_BLENDING);
+    }
+
+    if self.culling_mode() != CullingMode::Disabled {
+      flags.insert(MaterialFlags::BACKFACE_CULLING);
+    }
+
+    if self.scissor_mode() != ScissorMode::Disabled {
+      flags.insert(MaterialFlags::SCISSOR_TESTING);
+    }
+
+    if metadata.contains(ShaderFlags::ALPHA_TESTING) {
+      flags.insert(MaterialFlags::ALPHA_TESTING);
+    }
+
+    if metadata.contains(ShaderFlags::DEPTH_TESTING) {
+      flags.insert(MaterialFlags::DEPTH_TESTING);
+    }
+
+    if metadata.contains(ShaderFlags::DEPTH_WRITING) {
+      flags.insert(MaterialFlags::DEPTH_WRITING);
+    }
+
+    flags
+  }
+
   /// Gets the underlying [`ShaderUniformSet`] of the material.
   pub fn uniforms(&self) -> &ShaderUniformSet {
     &self.uniforms

modules/graphics/src/rendering/culling.rs

@@ -54,7 +54,10 @@ bitflags! {
 
 impl<'a> VisibleObjectSet<'a> {
   /// Groups the objects by material sorting key.
-  pub fn group_by_material(&self) -> impl Iterator<Item = (&'a Material, &[VisibleObject<'a>])> {
+  pub fn group_by_material(
+    &self,
+    required_flags: MaterialFlags,
+  ) -> impl Iterator<Item = (&'a Material, &[VisibleObject<'a>])> {
     self
       .objects
       .chunk_by(|a, b| {
@@ -63,7 +66,12 @@ impl<'a> VisibleObjectSet<'a> {
 
         a == b
       })
-      .map(|chunk| (chunk[0].material, chunk))
+      .filter(move |it| {
+        let flags = it[0].material.flags();
+
+        flags.contains(required_flags)
+      })
+      .map(|it| (it[0].material, it))
   }
 }
 
@@ -75,34 +83,8 @@ impl MaterialSortingKey {
   /// pipeline, and the last 32 bits represent the ID of the shader that should
   /// be used to render the material.
   pub fn for_material(material: &Material) -> Self {
-    let mut flags = MaterialFlags::empty();
-
     let shader = material.shader();
-    let metadata = shader.flags();
-
-    if material.blend_state() != BlendState::Disabled {
-      flags.insert(MaterialFlags::ALPHA_BLENDING);
-    }
-
-    if material.culling_mode() != CullingMode::Disabled {
-      flags.insert(MaterialFlags::BACKFACE_CULLING);
-    }
-
-    if material.scissor_mode() != ScissorMode::Disabled {
-      flags.insert(MaterialFlags::SCISSOR_TESTING);
-    }
-
-    if metadata.contains(ShaderFlags::ALPHA_TESTING) {
-      flags.insert(MaterialFlags::ALPHA_TESTING);
-    }
-
-    if metadata.contains(ShaderFlags::DEPTH_TESTING) {
-      flags.insert(MaterialFlags::DEPTH_TESTING);
-    }
-
-    if metadata.contains(ShaderFlags::DEPTH_WRITING) {
-      flags.insert(MaterialFlags::DEPTH_WRITING);
-    }
+    let flags = material.flags();
 
     let flags = u64::from(flags.bits());
     let shader = u64::from(shader.id());

modules/graphics/src/rendering/pipelines.rs

@@ -14,9 +14,11 @@ pub struct RenderFrame<'a> {
 impl<'a> RenderFrame<'a> {
   /// Draws the object visible to the given camera.
   pub fn draw_camera(&mut self, scene: &dyn RenderScene, camera: &dyn Camera) {
-    let visible_object_set = scene.cull_visible_objects(camera);
+    // find all objects visible to the camera
+    let visible_objects = scene.cull_visible_objects(camera);
 
-    for (material, group) in visible_object_set.group_by_material() {
+    // render each object, minimizing state changes by material
+    for (material, group) in visible_objects.group_by_material(MaterialFlags::all()) {
       self.queue.set_material(material);
 
       for entry in group {