From 519db119c6b6ae36134eeb880d80965c5e137a7c Mon Sep 17 00:00:00 2001
From: Christopher Lackner <clackner@cerbsim.com>
Date: Wed, 3 Jun 2026 16:35:38 +0200
Subject: [PATCH] pack all renders in one render pass (~20% render red per
 frame, grows with #renderes)

---
 webgpu/renderer.py | 36 +++++++++++++++++++++++++++++-------
 webgpu/scene.py    | 18 ++++++++++++------
 webgpu/shapes.py   | 21 ++++++++++-----------
 3 files changed, 51 insertions(+), 24 deletions(-)

diff --git a/webgpu/renderer.py b/webgpu/renderer.py
index 42134e7..1a396c6 100644
--- a/webgpu/renderer.py
+++ b/webgpu/renderer.py
@@ -1,3 +1,4 @@
+import contextlib
 import itertools
 from typing import Callable
 
@@ -73,12 +74,14 @@ class RenderOptions:
     command_encoder: CommandEncoder
     timestamp: float
     model_view_proj: object  # numpy array, updated by update_buffers
+    render_pass: object = None
 
     def __init__(self, camera: Camera, light: Light):
         self.light = light
         self.camera = camera
         self._camera_uniforms = None
         self.model_view_proj = None
+        self.render_pass = None
         self._extra_binding_providers = []
 
     def __getstate__(self):
@@ -89,6 +92,7 @@ def __setstate__(self, state):
         self.light = state["light"]
         self._camera_uniforms = None
         self.model_view_proj = None
+        self.render_pass = None
         self._extra_binding_providers = []
 
     def add_bindings(self, provider):
@@ -138,6 +142,25 @@ def begin_render_pass(self, **kwargs):
 
         return render_pass_encoder
 
+    @contextlib.contextmanager
+    def render_pass_scope(self):
+        """Yield the render pass a renderer should record into.
+
+        When the Scene has opened a shared frame pass (``self.render_pass`` is
+        set), reuse it and do NOT end it here — the Scene ends it once, after
+        all objects have been recorded, so the MSAA target is resolved a single
+        time per frame. When no shared pass is active (e.g. a renderer rendered
+        in isolation), open and close a private pass for backwards behaviour.
+        """
+        if self.render_pass is not None:
+            yield self.render_pass
+        else:
+            render_pass = self.begin_render_pass()
+            try:
+                yield render_pass
+            finally:
+                render_pass.end()
+
     def begin_select_pass(self, x, y, **kwargs):
         load_op = self.command_encoder.getLoadOp()
 
@@ -500,13 +523,12 @@ def create_render_pipeline(self, options: RenderOptions) -> None:
         self._last_transparent = self.transparent
 
     def render(self, options: RenderOptions) -> None:
-        render_pass = options.begin_render_pass()
-        render_pass.setPipeline(self.pipeline)
-        render_pass.setBindGroup(0, self.group)
-        for i, vertex_buffer in enumerate(self.vertex_buffers):
-            render_pass.setVertexBuffer(i, vertex_buffer)
-        render_pass.draw(self.n_vertices, self.n_instances)
-        render_pass.end()
+        with options.render_pass_scope() as render_pass:
+            render_pass.setPipeline(self.pipeline)
+            render_pass.setBindGroup(0, self.group)
+            for i, vertex_buffer in enumerate(self.vertex_buffers):
+                render_pass.setVertexBuffer(i, vertex_buffer)
+            render_pass.draw(self.n_vertices, self.n_instances)
 
     def render_opaque(self, options: RenderOptions) -> None:
         self.render(options)
diff --git a/webgpu/scene.py b/webgpu/scene.py
index 4dbe37f..610305d 100644
--- a/webgpu/scene.py
+++ b/webgpu/scene.py
@@ -425,12 +425,18 @@ def _render_objects(self, to_canvas=True, update_pipelines=True):
                         print("warning: object still needs update after update was done:", obj)
 
         options.command_encoder = self.device.createCommandEncoder()
-        for obj in self.render_objects:
-            if obj.active:
-                obj.render_opaque(options)
-        for obj in self.render_objects:
-            if obj.active:
-                obj.render_transparent(options)
+        render_pass = options.begin_render_pass()
+        options.render_pass = render_pass
+        try:
+            for obj in self.render_objects:
+                if obj.active:
+                    obj.render_opaque(options)
+            for obj in self.render_objects:
+                if obj.active:
+                    obj.render_transparent(options)
+        finally:
+            render_pass.end()
+            options.render_pass = None
 
         if to_canvas:
                 target_texture = self.canvas.target_texture
diff --git a/webgpu/shapes.py b/webgpu/shapes.py
index 40f2d3a..0ce4bab 100644
--- a/webgpu/shapes.py
+++ b/webgpu/shapes.py
@@ -486,17 +486,16 @@ def get_shader_code(self) -> str:
         return read_shader_file("shapes.wgsl")
 
     def render(self, options: RenderOptions) -> None:
-        render_pass = options.begin_render_pass()
-        render_pass.setPipeline(self.pipeline)
-        render_pass.setBindGroup(0, self.group)
-        for i, vertex_buffer in enumerate(self.vertex_buffers):
-            render_pass.setVertexBuffer(i, vertex_buffer)
-        render_pass.setIndexBuffer(self.triangle_buffer, IndexFormat.uint32)
-        render_pass.drawIndexed(
-            self.n_vertices,
-            self.n_instances,
-        )
-        render_pass.end()
+        with options.render_pass_scope() as render_pass:
+            render_pass.setPipeline(self.pipeline)
+            render_pass.setBindGroup(0, self.group)
+            for i, vertex_buffer in enumerate(self.vertex_buffers):
+                render_pass.setVertexBuffer(i, vertex_buffer)
+            render_pass.setIndexBuffer(self.triangle_buffer, IndexFormat.uint32)
+            render_pass.drawIndexed(
+                self.n_vertices,
+                self.n_instances,
+            )
 
     def select(self, options: RenderOptions, x, y) -> None:
         render_pass = options.begin_select_pass(x, y)