From 08b9c46ec48a72bda6bc014a3ae6bed0e5ab2797 Mon Sep 17 00:00:00 2001
From: Boris-Chengbiao Zhou <bobo1239@web.de>
Date: Mon, 15 Nov 2021 01:03:33 +0100
Subject: [PATCH] Validate strip_index_format (#2177)

The spec mandates that stripIndexFormat is set even when drawIndexed is
not used. (https://www.w3.org/TR/webgpu/#primitive-state)
There is some recent discussion about this though:
https://github.com/gpuweb/gpuweb/issues/2199
---
 wgpu-core/src/device/mod.rs     | 8 ++++++++
 wgpu-core/src/pipeline.rs       | 2 ++
 wgpu/examples/bunnymark/main.rs | 1 +
 wgpu/examples/mipmap/main.rs    | 2 ++
 4 files changed, 13 insertions(+)

diff --git a/wgpu-core/src/device/mod.rs b/wgpu-core/src/device/mod.rs
index d153515357..c67e925010 100644
--- a/wgpu-core/src/device/mod.rs
+++ b/wgpu-core/src/device/mod.rs
@@ -2211,6 +2211,14 @@ impl<A: HalApi> Device<A> {
             );
         }
 
+        if desc.primitive.strip_index_format.is_none() && desc.primitive.topology.is_strip() {
+            return Err(
+                pipeline::CreateRenderPipelineError::NoStripIndexFormatForStripTopology {
+                    topology: desc.primitive.topology,
+                },
+            );
+        }
+
         if desc.primitive.unclipped_depth {
             self.require_features(wgt::Features::DEPTH_CLIP_CONTROL)?;
         }
diff --git a/wgpu-core/src/pipeline.rs b/wgpu-core/src/pipeline.rs
index 2436f8cf25..bb8df5e6d0 100644
--- a/wgpu-core/src/pipeline.rs
+++ b/wgpu-core/src/pipeline.rs
@@ -309,6 +309,8 @@ pub enum CreateRenderPipelineError {
         strip_index_format: Option<wgt::IndexFormat>,
         topology: wgt::PrimitiveTopology,
     },
+    #[error("strip index format is None while using the strip topology {topology:?}")]
+    NoStripIndexFormatForStripTopology { topology: wgt::PrimitiveTopology },
     #[error("Conservative Rasterization is only supported for wgt::PolygonMode::Fill")]
     ConservativeRasterizationNonFillPolygonMode,
     #[error(transparent)]
diff --git a/wgpu/examples/bunnymark/main.rs b/wgpu/examples/bunnymark/main.rs
index f8c1c2b879..b99cc7fdad 100644
--- a/wgpu/examples/bunnymark/main.rs
+++ b/wgpu/examples/bunnymark/main.rs
@@ -125,6 +125,7 @@ impl framework::Example for Example {
             }),
             primitive: wgpu::PrimitiveState {
                 topology: wgpu::PrimitiveTopology::TriangleStrip,
+                strip_index_format: Some(wgpu::IndexFormat::Uint16),
                 ..wgpu::PrimitiveState::default()
             },
             depth_stencil: None,
diff --git a/wgpu/examples/mipmap/main.rs b/wgpu/examples/mipmap/main.rs
index f53bbc0ea4..82fd40e62b 100644
--- a/wgpu/examples/mipmap/main.rs
+++ b/wgpu/examples/mipmap/main.rs
@@ -99,6 +99,7 @@ impl Example {
             }),
             primitive: wgpu::PrimitiveState {
                 topology: wgpu::PrimitiveTopology::TriangleStrip,
+                strip_index_format: Some(wgpu::IndexFormat::Uint16),
                 ..Default::default()
             },
             depth_stencil: None,
@@ -292,6 +293,7 @@ impl framework::Example for Example {
             }),
             primitive: wgpu::PrimitiveState {
                 topology: wgpu::PrimitiveTopology::TriangleStrip,
+                strip_index_format: Some(wgpu::IndexFormat::Uint16),
                 front_face: wgpu::FrontFace::Ccw,
                 cull_mode: Some(wgpu::Face::Back),
                 ..Default::default()