From 5052f30d24758eaaba58b89037af63167536804e Mon Sep 17 00:00:00 2001
From: ColdPaleLight <zhangzhijian.123@bytedance.com>
Date: Thu, 23 Jun 2022 18:34:46 +0800
Subject: [PATCH 1/2] [Impeller] Metal:Reset Encoder viewport and scissor rect
 in case the command specifies no opinion

---
 .../renderer/backend/metal/render_pass_mtl.mm   | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/impeller/renderer/backend/metal/render_pass_mtl.mm b/impeller/renderer/backend/metal/render_pass_mtl.mm
index 2d0876dcbdf76..474dd62eb7a97 100644
--- a/impeller/renderer/backend/metal/render_pass_mtl.mm
+++ b/impeller/renderer/backend/metal/render_pass_mtl.mm
@@ -440,6 +440,16 @@ static bool Bind(PassBindingsCache& pass,
           .zfar = v.depth_range.z_far,
       };
       [encoder setViewport:viewport];
+    } else {
+      MTLViewport viewport = {
+          .originX = 0.0,
+          .originY = 0.0,
+          .width = static_cast<double>(GetRenderTargetSize().width),
+          .height = static_cast<double>(GetRenderTargetSize().height),
+          .znear = 0.0,
+          .zfar = 1.0,
+      };
+      [encoder setViewport:viewport];
     }
     if (command.scissor.has_value()) {
       auto s = command.scissor.value();
@@ -450,6 +460,13 @@ static bool Bind(PassBindingsCache& pass,
           .height = static_cast<NSUInteger>(s.size.height),
       };
       [encoder setScissorRect:scissor];
+    } else {
+      MTLScissorRect scissor = {
+          .x = 0,
+          .y = 0,
+          .width = static_cast<NSUInteger>(GetRenderTargetSize().width),
+          .height = static_cast<NSUInteger>(GetRenderTargetSize().height)};
+      [encoder setScissorRect:scissor];
     }
     if (!bind_stage_resources(command.vertex_bindings, ShaderStage::kVertex)) {
       return false;

From 3f9a428f7f01d519cb6744b947e8cd9d03894ac7 Mon Sep 17 00:00:00 2001
From: ColdPaleLight <zhangzhijian.123@bytedance.com>
Date: Fri, 24 Jun 2022 10:56:55 +0800
Subject: [PATCH 2/2] clean code

---
 .../renderer/backend/metal/render_pass_mtl.mm | 61 +++++++------------
 1 file changed, 22 insertions(+), 39 deletions(-)

diff --git a/impeller/renderer/backend/metal/render_pass_mtl.mm b/impeller/renderer/backend/metal/render_pass_mtl.mm
index 474dd62eb7a97..a257754b4c04f 100644
--- a/impeller/renderer/backend/metal/render_pass_mtl.mm
+++ b/impeller/renderer/backend/metal/render_pass_mtl.mm
@@ -429,45 +429,28 @@ static bool Bind(PassBindingsCache& pass,
                                        : MTLWindingCounterClockwise];
     [encoder setCullMode:ToMTLCullMode(command.cull_mode)];
     [encoder setStencilReferenceValue:command.stencil_reference];
-    if (command.viewport.has_value()) {
-      auto v = command.viewport.value();
-      MTLViewport viewport = {
-          .originX = v.rect.origin.x,
-          .originY = v.rect.origin.y,
-          .width = v.rect.size.width,
-          .height = v.rect.size.height,
-          .znear = v.depth_range.z_near,
-          .zfar = v.depth_range.z_far,
-      };
-      [encoder setViewport:viewport];
-    } else {
-      MTLViewport viewport = {
-          .originX = 0.0,
-          .originY = 0.0,
-          .width = static_cast<double>(GetRenderTargetSize().width),
-          .height = static_cast<double>(GetRenderTargetSize().height),
-          .znear = 0.0,
-          .zfar = 1.0,
-      };
-      [encoder setViewport:viewport];
-    }
-    if (command.scissor.has_value()) {
-      auto s = command.scissor.value();
-      MTLScissorRect scissor = {
-          .x = static_cast<NSUInteger>(s.origin.x),
-          .y = static_cast<NSUInteger>(s.origin.y),
-          .width = static_cast<NSUInteger>(s.size.width),
-          .height = static_cast<NSUInteger>(s.size.height),
-      };
-      [encoder setScissorRect:scissor];
-    } else {
-      MTLScissorRect scissor = {
-          .x = 0,
-          .y = 0,
-          .width = static_cast<NSUInteger>(GetRenderTargetSize().width),
-          .height = static_cast<NSUInteger>(GetRenderTargetSize().height)};
-      [encoder setScissorRect:scissor];
-    }
+
+    auto v = command.viewport.value_or<Viewport>(
+        {.rect = Rect::MakeSize(Size(GetRenderTargetSize()))});
+    MTLViewport viewport = {
+        .originX = v.rect.origin.x,
+        .originY = v.rect.origin.y,
+        .width = v.rect.size.width,
+        .height = v.rect.size.height,
+        .znear = v.depth_range.z_near,
+        .zfar = v.depth_range.z_far,
+    };
+    [encoder setViewport:viewport];
+
+    auto s = command.scissor.value_or(IRect::MakeSize(GetRenderTargetSize()));
+    MTLScissorRect scissor = {
+        .x = static_cast<NSUInteger>(s.origin.x),
+        .y = static_cast<NSUInteger>(s.origin.y),
+        .width = static_cast<NSUInteger>(s.size.width),
+        .height = static_cast<NSUInteger>(s.size.height),
+    };
+    [encoder setScissorRect:scissor];
+
     if (!bind_stage_resources(command.vertex_bindings, ShaderStage::kVertex)) {
       return false;
     }