Use configurable overestimate to account for incorrect maxVertex

* We do this already on D3D12, this applies the same change to Vulkan -
  maxVertex can't really be trusted but we hope it is approximately right or the
  VBs are small, we don't want to copy the whole VB since it may be massive.

renderdoc/driver/vulkan/vk_acceleration_structure.cpp

@@ -28,6 +28,13 @@
 #include "vk_manager.h"
 
 RDOC_EXTERN_CONFIG(bool, Vulkan_Debug_SingleSubmitFlushing);
+RDOC_CONFIG(uint32_t, Vulkan_Debug_RT_MaxVertexIncrement, 1000,
+            "Amount to add to the API-provided max vertex when building a BLAS with an index "
+            "buffer, to account for incorrectly set values by application.");
+RDOC_CONFIG(
+    uint32_t, Vulkan_Debug_RT_MaxVertexPercentIncrease, 10,
+    "Percentage increase for the API-provided max vertex when building a BLAS with an index "
+    "buffer, to account for incorrectly set values by application.");
 
 namespace
 {
@@ -323,9 +330,17 @@ RDResult VulkanAccelerationStructureManager::CopyInputBuffers(
 
         if(indexData)
         {
-          // If we're using an index buffer we don't know how much of the vertex buffer we need,
-          // and we can't trust the app to set maxVertex correctly, so we take the whole buffer
-          vertexData.size = vertexData.rao.record->memSize - vertexData.rao.offset;
+          // don't take maxVertex as perfect, applications have no reason to set it correctly for
+          // everything to work with drivers, and likely no validation. Add an overestimate factor
+          uint32_t untrustedVertexCount = triInfo.maxVertex;
+          uint32_t estimatedVertexCount =
+              untrustedVertexCount +
+              (untrustedVertexCount / 100) * Vulkan_Debug_RT_MaxVertexPercentIncrease() +
+              Vulkan_Debug_RT_MaxVertexIncrement();
+
+          // don't read more than what is left in the buffer
+          vertexData.size = RDCMIN(triInfo.vertexStride * estimatedVertexCount,
+                                   vertexData.rao.record->memSize - vertexData.rao.offset);
           vertexData.SetReadPosition(0);
         }
         else