dispatch uniform fixes

crates/processing_core/src/error.rs

@@ -58,6 +58,8 @@ pub enum ProcessingError {
     PipelineCompileError(String),
     #[error("Pipeline not ready after {0} frames")]
     PipelineNotReady(u32),
+    #[error("`{0}` isn't on the GPU yet")]
+    ResourceNotReady(String),
     #[error("Particles not found")]
     ParticlesNotFound,
     #[error("Grid not found")]

crates/processing_render/src/compute.rs

@@ -359,6 +359,18 @@ pub fn dispatch(
         .clone();
 
     let reflection = shader.reflection();
+    // a missing GPU resource drops its binding, and wgpu panics on an incomplete bind group
+    for param in reflection.parameters() {
+        let Some(name) = param.name() else { continue };
+        let ready = match (shader.buffer_handle(name), shader.image_handle(name)) {
+            (Some(handle), _) => gpu_buffers.get(handle).is_some(),
+            (_, Some(handle)) => gpu_images.get(handle).is_some(),
+            _ => true,
+        };
+        if !ready {
+            return Err(ProcessingError::ResourceNotReady(name.to_string()));
+        }
+    }
 
     let mut bind_groups = Vec::new();
     for (group, desc) in &layout_descriptors {

crates/processing_render/src/lib.rs

@@ -2553,7 +2553,10 @@ pub(crate) fn compute_dispatch_no_update(
     z: u32,
 ) -> error::Result<()> {
     app_mut(|app| match dispatch_inner(app, entity, x, y, z) {
-        Err(error::ProcessingError::PipelineNotReady(_)) => {
+        Err(
+            error::ProcessingError::PipelineNotReady(_)
+            | error::ProcessingError::ResourceNotReady(_),
+        ) => {
             app.update();
             dispatch_inner(app, entity, x, y, z)
         }

crates/processing_render/src/material/custom.rs

@@ -322,11 +322,27 @@ pub(crate) fn apply_reflect_field(
         return Ok(());
     }
 
-    let param_name = find_param_containing_field(shader, name);
-    if let Some(param_name) = param_name
-        && let Some(param) = shader.field_mut(&param_name)
+    // `struct.field` picks a struct explicitly
+    let (param_name, field_name) = match name.split_once('.') {
+        Some((param, field)) => (param.to_string(), field),
+        None => {
+            let params = params_containing_field(shader, name);
+            if params.len() > 1 {
+                return Err(ProcessingError::InvalidArgument(format!(
+                    "`{name}` is a field of {}; name one, e.g. `{}.{name}`",
+                    params.join(" and "),
+                    params[0],
+                )));
+            }
+            let Some(param) = params.into_iter().next() else {
+                return Err(ProcessingError::UnknownShaderProperty(name.to_string()));
+            };
+            (param, name)
+        }
+    };
+    if let Some(param) = shader.field_mut(&param_name)
         && let ReflectMut::Struct(s) = param.reflect_mut()
-        && let Some(field) = s.field_mut(name)
+        && let Some(field) = s.field_mut(field_name)
     {
         apply_field_coerced(field, value);
         return Ok(());
@@ -509,15 +525,20 @@ pub(crate) fn find_param_containing_field(
     shader: &DynamicShader,
     field_name: &str,
 ) -> Option<String> {
-    for i in 0..shader.field_len() {
-        if let Some(field) = shader.field_at(i)
-            && let ReflectRef::Struct(s) = field.reflect_ref()
-            && s.field(field_name).is_some()
-        {
-            return shader.name_at(i).map(|s: &str| s.to_string());
-        }
-    }
-    None
+    params_containing_field(shader, field_name)
+        .into_iter()
+        .next()
+}
+
+fn params_containing_field(shader: &DynamicShader, field_name: &str) -> Vec<String> {
+    (0..shader.field_len())
+        .filter(|&i| {
+            shader.field_at(i).is_some_and(|field| {
+                matches!(field.reflect_ref(), ReflectRef::Struct(s) if s.field(field_name).is_some())
+            })
+        })
+        .filter_map(|i| shader.name_at(i).map(str::to_string))
+        .collect()
 }
 
 pub struct CustomMaterialPlugin;

crates/processing_render/src/particles/algebra.rs

@@ -5,7 +5,7 @@ use bevy::prelude::Entity;
 use processing_core::error::{ProcessingError, Result};
 
 use crate::shader_value::ShaderValue;
-use crate::{buffer_size, compute_dispatch, compute_set, shader_create_with_features};
+use crate::{buffer_size, compute_dispatch_no_update, compute_set, shader_create_with_features};
 
 const WG: u32 = 64;
 
@@ -96,7 +96,7 @@ static MAP: Mutex<Option<(Entity, Entity)>> = Mutex::new(None);
 
 fn dispatch_particles(compute: Entity, floats: u64, components: u32) -> Result<()> {
     let n = (floats / components as u64) as u32;
-    compute_dispatch(compute, n.div_ceil(WG), 1, 1)
+    compute_dispatch_no_update(compute, n.div_ceil(WG), 1, 1)
 }
 
 fn check_components(verb: &str, components: u32) -> Result<()> {
@@ -373,7 +373,7 @@ pub fn lookup(
     compute_set(c, "tex", ShaderValue::Texture(tex))?;
     compute_set(c, "samp", ShaderValue::Texture(tex))?;
     let n = (buffer_size(dst)? / 16) as u32;
-    compute_dispatch(c, n.div_ceil(WG), 1, 1)
+    compute_dispatch_no_update(c, n.div_ceil(WG), 1, 1)
 }
 
 pub const REDUCE_LENGTH: u32 = 0;
@@ -430,7 +430,7 @@ pub fn reduce_components(dst: Entity, src: Entity, components: u32, op: u32) ->
     compute_set(c, "components", ShaderValue::UInt(components))?;
     compute_set(c, "op", ShaderValue::UInt(op))?;
     let n = (buffer_size(dst)? / 4) as u32;
-    compute_dispatch(c, n.div_ceil(WG), 1, 1)
+    compute_dispatch_no_update(c, n.div_ceil(WG), 1, 1)
 }
 
 const EXTRACT_SRC: &str = r#"
@@ -465,7 +465,7 @@ pub fn extract(dst: Entity, src: Entity, components: u32, index: u32) -> Result<
     compute_set(c, "components", ShaderValue::UInt(components))?;
     compute_set(c, "index", ShaderValue::UInt(index))?;
     let n = (buffer_size(dst)? / 4) as u32;
-    compute_dispatch(c, n.div_ceil(WG), 1, 1)
+    compute_dispatch_no_update(c, n.div_ceil(WG), 1, 1)
 }
 
 const PACK_SRC: &str = r#"
@@ -534,7 +534,7 @@ pub fn pack(dst: Entity, sources: &[Entity]) -> Result<()> {
     compute_set(c, "dst", ShaderValue::Buffer(dst))?;
     compute_set(c, "components", ShaderValue::UInt(components))?;
     let n = (buffer_size(sources[0])? / 4) as u32;
-    compute_dispatch(c, n.div_ceil(WG), 1, 1)
+    compute_dispatch_no_update(c, n.div_ceil(WG), 1, 1)
 }
 
 pub const GEN_UNIFORM: u32 = 0;