Fix materialData array alignment issues.

res/engine/shaders/include/data/MaterialData.glsl

@@ -9,8 +9,13 @@ struct MaterialData {
     /** Defines how much specular light will be reflected (value in range [0.0F; 1.0F]). */
     float roughness;
 
-    /** Padding for alignment simplicity. */
-    vec3 pad;
+    /** Explicit padding for clarity. */
+    /** `vec3` does not work here because GLSL requires 16 bytes of alignment of `vec3`s but we have 4 byte alignment here. */
+    float pad1;
+    // silence doc checker
+    float pad2;
+    // silence doc checker
+    float pad3;
 };
 
 /** Material data for all meshes, use indices from root/push constants to index into this array. */

src/engine_lib/private/material/Material.cpp

@@ -421,14 +421,14 @@ namespace ne {
         // Set flag before adding binding data.
         bIsShaderResourcesAllocated = true;
 
-        // Set material constant buffer.
+        // Set material data binding.
         setShaderCpuWriteResourceBindingData(
-            sMaterialShaderConstantBufferName,
+            sMaterialShaderBufferName,
             sizeof(MaterialShaderConstants),
             [this]() -> void* { return onStartUpdatingShaderMeshConstants(); },
             [this]() { onFinishedUpdatingShaderMeshConstants(); });
 
-        // Set diffuse texture (if path is set).
+        // Set diffuse texture binding (if path is set).
         if (!sDiffuseTexturePathRelativeRes.empty()) {
             setShaderTextureResourceBindingData(
                 sMaterialShaderDiffuseTextureName, sDiffuseTexturePathRelativeRes);
@@ -641,7 +641,7 @@ namespace ne {
         mtxShaderMaterialDataConstants.second.diffuseColor.y = diffuseColor.y;
         mtxShaderMaterialDataConstants.second.diffuseColor.z = diffuseColor.z;
 
-        markShaderCpuWriteResourceAsNeedsUpdate(sMaterialShaderConstantBufferName);
+        markShaderCpuWriteResourceAsNeedsUpdate(sMaterialShaderBufferName);
     }
 
     void Material::setSpecularColor(const glm::vec3& specularColor) {
@@ -655,7 +655,7 @@ namespace ne {
         mtxShaderMaterialDataConstants.second.specularColor.y = specularColor.y;
         mtxShaderMaterialDataConstants.second.specularColor.z = specularColor.z;
 
-        markShaderCpuWriteResourceAsNeedsUpdate(sMaterialShaderConstantBufferName);
+        markShaderCpuWriteResourceAsNeedsUpdate(sMaterialShaderBufferName);
     }
 
     void Material::setRoughness(float roughness) {
@@ -667,7 +667,7 @@ namespace ne {
         // Save new opacity for shaders.
         mtxShaderMaterialDataConstants.second.roughness = this->roughness;
 
-        markShaderCpuWriteResourceAsNeedsUpdate(sMaterialShaderConstantBufferName);
+        markShaderCpuWriteResourceAsNeedsUpdate(sMaterialShaderBufferName);
     }
 
     void Material::setOpacity(float opacity) {
@@ -679,7 +679,7 @@ namespace ne {
         // Save new opacity for shaders.
         mtxShaderMaterialDataConstants.second.diffuseColor.w = this->opacity;
 
-        markShaderCpuWriteResourceAsNeedsUpdate(sMaterialShaderConstantBufferName);
+        markShaderCpuWriteResourceAsNeedsUpdate(sMaterialShaderBufferName);
     }
 
     std::string Material::getVertexShaderName() const { return sVertexShaderName; }

src/engine_lib/private/shader/general/resources/cpuwrite/DynamicCpuWriteShaderResourceArray.cpp

@@ -203,7 +203,7 @@ namespace ne {
 
         // Create a new buffer.
         auto result = pResourceManager->createResourceWithCpuWriteAccess(
-            std::format("\"{}\" GPU array", sHandledShaderResourceName),
+            std::format("\"{}\" CPU-write dynamic array", sHandledShaderResourceName),
             iElementSizeInBytes,
             iCapacity,
             true);

src/engine_lib/private/shader/general/resources/cpuwrite/ShaderCpuWriteResource.cpp

@@ -52,7 +52,9 @@ namespace ne {
             return Error("shader resource array manager is `nullptr`");
         }
 
-        // Reserve a space for this shader resource's data per frame resource.
+        // Reserve a space for this shader resource's data per frame resource
+        // (one slot per frame in-flight because we operate on CPU-write resources
+        // so we have to keep N copies of the data in case it's changing to avoid stopping the GPU).
         for (unsigned int i = 0; i < FrameResourceManager::getFrameResourceCount(); i++) {
             auto result = pShaderResourceArrayManager->reserveSlotsInArray(pShaderResource.get());
             if (std::holds_alternative<Error>(result)) [[unlikely]] {

src/engine_lib/public/material/Material.h

@@ -368,7 +368,7 @@ namespace ne RNAMESPACE() {
             /** Defines how much specular light will be reflected. */
             alignas(iVkScalarAlignment) float roughness = 0.0F;
 
-            /** Padding for alignment simplicity. */
+            /** Explicit padding for clarity. */
             float pad[3];
         };
 
@@ -665,8 +665,8 @@ namespace ne RNAMESPACE() {
         /** Whether @ref allocateShaderResources was called or not. */
         bool bIsShaderResourcesAllocated = false;
 
-        /** Name of the constant buffer used to store material data in shaders. */
-        static inline const auto sMaterialShaderConstantBufferName = "materialData";
+        /** Name of the buffer used to store material data in shaders. */
+        static inline const auto sMaterialShaderBufferName = "materialData";
 
         /** Name of the resource used to store diffuse texture in shaders. */
         static inline const auto sMaterialShaderDiffuseTextureName = "diffuseTexture";