Fix issue with missing capability when enabling shaderc optimizations

See gfx-rs/wgpu#4915

Also:
* Remove unused vert-out frag-in variables from shaders (naga doesn't
  like this probably because they are optimized out on the fragment
  side). This restriction from naga may be relaxed in the future
  see gfx-rs/wgpu#3748.
* Enable OptimizationLevel::Performance for shaderc by default
* Add a environment variable VOXYGEN_SHADERC_OPTS for disabling this
  (e.g. to test if it actually makes a difference on any platform).
  (TODO: testing might be easier if there was a way to do toggle it
  without restarting...)

Cargo.toml

@@ -157,13 +157,14 @@ async-trait = "0.1.42"
 
 [patch.crates-io]
 shred = { git = "https://github.com/amethyst/shred.git", rev = "5d52c6fc390dd04c12158633e77591f6523d1f85" }
-# This is needed because of an issue with spirv & naga in wgpu 0.18, and there's an issue
-# with uint in uniforms for gl.
-wgpu = { git = "https://github.com/IsseW/wgpu", rev = "5ea160164" }
+# This is needed because of:
+# * an issue with spirv & naga in wgpu 0.18 (I assume this is fixed upstream but not in 0.18)
+# * an issue with uint in uniforms for gl. (potentially fixed in 0.19?)
+# * an issue with releasing current context on Windows opengl (fixed in 0.19.1)
+# * another spirv issue: unused builtins not always being removed.  (upstream PR open)
+wgpu = { git = "https://github.com/Imberflur/wgpu.git", tag = "0.18-with-fixes-for-veloren-v1" }
+# wgpu = { path = "../wgpu/wgpu" }
 
-# # use the latest fixes in naga (remove when updates trickle down to wgpu-rs)
-# naga = { git = "https://github.com/gfx-rs/naga.git", rev = "3a0f0144112ff621dd7f731bf455adf6cab19164" }
-# naga = { path = "../naga" }
 # keyboard-keynames = { git = "https://gitlab.com/Capucho/keyboard-keynames.git", rev = "7b1375ee4ea01d0e0b80c419cb27f0498e67df3a" }
 
 # # Uncomment this to use a local fork of winit (for testing purposes)
@@ -174,6 +175,5 @@ wgpu = { git = "https://github.com/IsseW/wgpu", rev = "5ea160164" }
 # wgpu-hal = { path = "../wgpu/wgpu-hal" }
 # wgpu-core = { path = "../wgpu/wgpu-core" }
 # wgpu-types = { path = "../wgpu/wgpu-types" }
+# naga = { path = "../wgpu/naga" }
 
-[patch."https://github.com/gfx-rs/naga"]
-# naga = { path = "../naga" }

assets/voxygen/shaders/terrain-frag.glsl

@@ -27,7 +27,6 @@ layout(location = 0) in vec3 f_pos;
 // in vec3 f_chunk_pos;
 // #ifdef FLUID_MODE_SHINY
 layout(location = 1) flat in uint f_pos_norm;
-layout(location = 2) flat in float f_load_time;
 // #else
 // const uint f_pos_norm = 0u;
 // #endif

assets/voxygen/shaders/terrain-vert.glsl

@@ -49,7 +49,6 @@ uniform u_locals {
 layout(location = 0) out vec3 f_pos;
 // #ifdef FLUID_MODE_SHINY
 layout(location = 1) flat out uint f_pos_norm;
-layout(location = 2) flat out float f_load_time;
 
 // #if (SHADOW_MODE == SHADOW_MODE_MAP)
 // out vec4 sun_pos;
@@ -77,8 +76,6 @@ void main() {
 
     f_pos = (model_mat * vec4(f_chunk_pos, 1.0)).xyz - focus_off.xyz;
 
-    f_load_time = load_time;
-
     vec3 v_pos = f_pos;
 
     // Terrain 'pop-in' effect

assets/voxygen/shaders/trail-frag.glsl

@@ -20,8 +20,6 @@
 
 #include <globals.glsl>
 
-layout(location = 0) in vec3 f_pos;
-
 layout(location = 0) out vec4 tgt_color;
 
 #include <sky.glsl>

assets/voxygen/shaders/trail-vert.glsl

@@ -4,10 +4,6 @@
 
 layout(location = 0) in vec3 v_pos;
 
-layout(location = 0) out vec3 f_pos;
-
 void main() {
-    f_pos = v_pos;
-
-    gl_Position = all_mat * vec4(f_pos - focus_off.xyz, 1);
+    gl_Position = all_mat * vec4(v_pos - focus_off.xyz, 1);
 }

voxygen/src/render/renderer/pipeline_creation.rs

@@ -14,6 +14,7 @@ use super::{
 };
 use common_base::{prof_span, prof_span_alloc};
 use std::sync::Arc;
+use tracing::info;
 
 /// All the pipelines
 pub struct Pipelines {
@@ -282,7 +283,26 @@ impl ShaderModules {
 
         let mut compiler = Compiler::new().ok_or(RenderError::ErrorInitializingCompiler)?;
         let mut options = CompileOptions::new().ok_or(RenderError::ErrorInitializingCompiler)?;
-        options.set_optimization_level(OptimizationLevel::Zero);
+        use std::sync::OnceLock;
+        static OPTS: OnceLock<bool> = OnceLock::new();
+        let shaderc_opts = *OPTS.get_or_init(|| {
+            match std::env::var("VOXYGEN_SHADERC_OPTS").as_ref().map(|s| &**s) {
+                Ok("0" | "no") => {
+                    info!("Disabled optimization by shaderc.");
+                    false
+                },
+                Ok("1" | "yes") | Ok(_) | Err(_) => {
+                    info!("Enabled optimization by shaderc.");
+                    true
+                },
+            }
+        });
+
+        if shaderc_opts {
+            options.set_optimization_level(OptimizationLevel::Performance);
+        } else {
+            options.set_optimization_level(OptimizationLevel::Zero);
+        }
         options.set_forced_version_profile(430, shaderc::GlslProfile::Core);
         // options.set_generate_debug_info();
         options.set_include_callback(move |name, _, shader_name, _| {