From 3a6c6c2adde98973828be10508031143dc8926da Mon Sep 17 00:00:00 2001
From: Torstein Grindvik <torstein.grindvik@nordicsemi.no>
Date: Sun, 15 Jan 2023 09:11:52 +0100
Subject: [PATCH] Picking support to alpha mask, transparency 3d

Signed-off-by: Torstein Grindvik <torstein.grindvik@nordicsemi.no>
---
 .../src/core_3d/main_pass_3d_node.rs          | 29 ++++++++++++++-----
 crates/bevy_pbr/src/render/mesh.rs            |  1 -
 examples/3d/transparency_3d.rs                | 16 ++++++----
 3 files changed, 31 insertions(+), 15 deletions(-)

diff --git a/crates/bevy_core_pipeline/src/core_3d/main_pass_3d_node.rs b/crates/bevy_core_pipeline/src/core_3d/main_pass_3d_node.rs
index bf42a535713923..79826cc7641e60 100644
--- a/crates/bevy_core_pipeline/src/core_3d/main_pass_3d_node.rs
+++ b/crates/bevy_core_pipeline/src/core_3d/main_pass_3d_node.rs
@@ -94,6 +94,7 @@ impl Node for MainPass3dNode {
             if let Some(picking_textures) = picking_textures {
                 color_attachments.push(Some(picking_textures.get_color_attachment(Operations {
                     // If the wish is to not clear the screen, don't clear the picking buffer either.
+                    // This may happen in situations such as a split screen game.
                     load: match camera_3d.clear_color {
                         ClearColorConfig::None => LoadOp::Load,
                         _ => LoadOp::Clear(PickingTextures::clear_color()),
@@ -132,13 +133,19 @@ impl Node for MainPass3dNode {
             #[cfg(feature = "trace")]
             let _main_alpha_mask_pass_3d_span = info_span!("main_alpha_mask_pass_3d").entered();
 
+            let operations = Operations {
+                load: LoadOp::Load,
+                store: true,
+            };
+            let mut color_attachments = vec![Some(target.get_color_attachment(operations))];
+            if let Some(picking_textures) = picking_textures {
+                color_attachments.push(Some(picking_textures.get_color_attachment(operations)));
+            }
+
             let mut render_pass = render_context.begin_tracked_render_pass(RenderPassDescriptor {
                 label: Some("main_alpha_mask_pass_3d"),
                 // NOTE: The alpha_mask pass loads the color buffer as well as overwriting it where appropriate.
-                color_attachments: &[Some(target.get_color_attachment(Operations {
-                    load: LoadOp::Load,
-                    store: true,
-                }))],
+                color_attachments: &color_attachments,
                 depth_stencil_attachment: Some(RenderPassDepthStencilAttachment {
                     view: &depth.view,
                     // NOTE: The alpha mask pass loads the depth buffer and possibly overwrites it
@@ -163,13 +170,19 @@ impl Node for MainPass3dNode {
             #[cfg(feature = "trace")]
             let _main_transparent_pass_3d_span = info_span!("main_transparent_pass_3d").entered();
 
+            let operations = Operations {
+                load: LoadOp::Load,
+                store: true,
+            };
+            let mut color_attachments = vec![Some(target.get_color_attachment(operations))];
+            if let Some(picking_textures) = picking_textures {
+                color_attachments.push(Some(picking_textures.get_color_attachment(operations)));
+            }
+
             let mut render_pass = render_context.begin_tracked_render_pass(RenderPassDescriptor {
                 label: Some("main_transparent_pass_3d"),
                 // NOTE: The transparent pass loads the color buffer as well as overwriting it where appropriate.
-                color_attachments: &[Some(target.get_color_attachment(Operations {
-                    load: LoadOp::Load,
-                    store: true,
-                }))],
+                color_attachments: &color_attachments,
                 depth_stencil_attachment: Some(RenderPassDepthStencilAttachment {
                     view: &depth.view,
                     // NOTE: For the transparent pass we load the depth buffer. There should be no
diff --git a/crates/bevy_pbr/src/render/mesh.rs b/crates/bevy_pbr/src/render/mesh.rs
index 96e2488a877e0f..61bf821a682867 100644
--- a/crates/bevy_pbr/src/render/mesh.rs
+++ b/crates/bevy_pbr/src/render/mesh.rs
@@ -666,7 +666,6 @@ impl SpecializedMeshPipeline for MeshPipeline {
 
             targets.push(Some(ColorTargetState {
                 format: PICKING_TEXTURE_FORMAT,
-                // TODO: Check that we support both pipelines
                 blend,
                 write_mask: ColorWrites::ALL,
             }));
diff --git a/examples/3d/transparency_3d.rs b/examples/3d/transparency_3d.rs
index 437c291589f2d3..2879803b4181ee 100644
--- a/examples/3d/transparency_3d.rs
+++ b/examples/3d/transparency_3d.rs
@@ -2,11 +2,12 @@
 //! Shows the effects of different blend modes.
 //! The `fade_transparency` system smoothly changes the transparency over time.
 
-use bevy::prelude::*;
+use bevy::{prelude::*, render::picking::Picking};
 
 fn main() {
     App::new()
-        .insert_resource(Msaa { samples: 4 })
+        // .insert_resource(Msaa { samples: 4 })
+        .insert_resource(Msaa { samples: 1 })
         .add_plugins(DefaultPlugins)
         .add_startup_system(setup)
         .add_system(fade_transparency)
@@ -99,10 +100,13 @@ fn setup(
         ..default()
     });
     // camera
-    commands.spawn(Camera3dBundle {
-        transform: Transform::from_xyz(-2.0, 3.0, 5.0).looking_at(Vec3::ZERO, Vec3::Y),
-        ..default()
-    });
+    commands.spawn((
+        Camera3dBundle {
+            transform: Transform::from_xyz(-2.0, 3.0, 5.0).looking_at(Vec3::ZERO, Vec3::Y),
+            ..default()
+        },
+        Picking::default(),
+    ));
 }
 
 /// Fades the alpha channel of all materials between 0 and 1 over time.