restore blas flags

Author: TheNumbat

rvk/acceleration.cpp

@@ -214,7 +214,7 @@ Opt<BLAS::Staged> BLAS::make(Arc<Device_Memory, Alloc> memory, Buffer data,
             .sType = VK_STRUCTURE_TYPE_ACCELERATION_STRUCTURE_BUILD_GEOMETRY_INFO_KHR,
             .type = VK_ACCELERATION_STRUCTURE_TYPE_BOTTOM_LEVEL_KHR,
             .flags = VK_BUILD_ACCELERATION_STRUCTURE_ALLOW_DATA_ACCESS_KHR |
-                     VK_BUILD_ACCELERATION_STRUCTURE_ALLOW_UPDATE_BIT_KHR,
+                     VK_BUILD_ACCELERATION_STRUCTURE_PREFER_FAST_BUILD_BIT_KHR,
             .mode = VK_BUILD_ACCELERATION_STRUCTURE_MODE_BUILD_KHR,
             .geometryCount = static_cast<u32>(geometries.length()),
             .pGeometries = geometries.data(),
@@ -311,7 +311,7 @@ BLAS BLAS::build(Commands& cmds, Staged buffers) {
             .sType = VK_STRUCTURE_TYPE_ACCELERATION_STRUCTURE_BUILD_GEOMETRY_INFO_KHR,
             .type = VK_ACCELERATION_STRUCTURE_TYPE_BOTTOM_LEVEL_KHR,
             .flags = VK_BUILD_ACCELERATION_STRUCTURE_ALLOW_DATA_ACCESS_KHR |
-                     VK_BUILD_ACCELERATION_STRUCTURE_ALLOW_UPDATE_BIT_KHR,
+                     VK_BUILD_ACCELERATION_STRUCTURE_PREFER_FAST_BUILD_BIT_KHR,
             .mode = VK_BUILD_ACCELERATION_STRUCTURE_MODE_BUILD_KHR,
             .dstAccelerationStructure = acceleration_structure,
             .geometryCount = static_cast<u32>(geometries.length()),