Add allow_capacity_increase option to AllocationCreateDesc

This allows the user to bound the growth of the capacity without relying
on the driver to return ERROR_OUT_OF_DEVICE_MEMORY (which they sometimes
don't).

Author: ftilde

README.md

@@ -62,6 +62,7 @@ let allocation = allocator
         location: MemoryLocation::CpuToGpu,
         linear: true, // Buffers are always linear
         allocation_scheme: AllocationScheme::GpuAllocatorManaged,
+        allow_capacity_increase: true,
     }).unwrap();
 
 // Bind memory to the buffer

examples/vulkan-buffer.rs

@@ -110,6 +110,7 @@ fn main() {
                 linear: true,
                 allocation_scheme: AllocationScheme::GpuAllocatorManaged,
                 name: "Test allocation (Gpu Only)",
+                allow_capacity_increase: true,
             })
             .unwrap();
 
@@ -143,6 +144,7 @@ fn main() {
                 linear: true,
                 allocation_scheme: AllocationScheme::GpuAllocatorManaged,
                 name: "Test allocation (Cpu to Gpu)",
+                allow_capacity_increase: true,
             })
             .unwrap();
 
@@ -176,6 +178,7 @@ fn main() {
                 linear: true,
                 allocation_scheme: AllocationScheme::GpuAllocatorManaged,
                 name: "Test allocation (Gpu to Cpu)",
+                allow_capacity_increase: true,
             })
             .unwrap();
 

src/lib.rs

@@ -66,6 +66,7 @@
 //!         location: MemoryLocation::CpuToGpu,
 //!         linear: true, // Buffers are always linear
 //!         allocation_scheme: AllocationScheme::GpuAllocatorManaged,
+//!         allow_capacity_increase: true,
 //!     }).unwrap();
 //!
 //! // Bind memory to the buffer

src/vulkan/mod.rs

@@ -37,6 +37,8 @@ pub struct AllocationCreateDesc<'a> {
     pub linear: bool,
     /// Determines how this allocation should be managed.
     pub allocation_scheme: AllocationScheme,
+    /// Allow the allocator to request additional memory from the device to fulfill this request.
+    pub allow_capacity_increase: bool,
 }
 
 /// Wrapper type to only mark a raw pointer [`Send`] + [`Sync`] without having to
@@ -579,6 +581,10 @@ impl MemoryType {
             }
         }
 
+        if !desc.allow_capacity_increase {
+            return Err(AllocationError::OutOfMemory);
+        }
+
         let new_memory_block = MemoryBlock::new(
             device,
             memblock_size,