source/blender/gpu/vulkan/vk_buffer.hh

@@ -66,6 +66,8 @@ class VKBuffer {
  *
  * VKImmediate mode uses a single VKBuffer with multiple vertex layouts. Those layouts are send to
  * the command buffer containing an offset.
+ *
+ * VKIndexBuffer uses this when it is a subrange of another buffer.
  */
 struct VKBufferWithOffset {
   VKBuffer &buffer;

source/blender/gpu/vulkan/vk_command_buffer.cc

@@ -116,12 +116,12 @@ void VKCommandBuffer::bind(const uint32_t binding,
   vkCmdBindVertexBuffers(vk_command_buffer_, binding, 1, &vk_vertex_buffer, &offset);
 }
 
-void VKCommandBuffer::bind(const VKIndexBuffer &index_buffer, VkIndexType index_type)
+void VKCommandBuffer::bind(const VKBufferWithOffset &index_buffer, VkIndexType index_type)
 {
   validate_framebuffer_exists();
   ensure_active_framebuffer();
-  VkBuffer vk_buffer = index_buffer.vk_handle();
-  vkCmdBindIndexBuffer(vk_command_buffer_, vk_buffer, 0, index_type);
+  vkCmdBindIndexBuffer(
+      vk_command_buffer_, index_buffer.buffer.vk_handle(), index_buffer.offset, index_type);
 }
 
 void VKCommandBuffer::begin_render_pass(const VKFrameBuffer &framebuffer)

source/blender/gpu/vulkan/vk_command_buffer.hh

@@ -144,7 +144,8 @@ class VKCommandBuffer : NonCopyable, NonMovable {
   /* Bind the given buffer as a vertex buffer. */
   void bind(const uint32_t binding, const VKBufferWithOffset &vertex_buffer);
   void bind(const uint32_t binding, const VkBuffer &vk_vertex_buffer, const VkDeviceSize offset);
-  void bind(const VKIndexBuffer &index_buffer, VkIndexType index_type);
+  /* Bind the given buffer as an index buffer. */
+  void bind(const VKBufferWithOffset &index_buffer, VkIndexType index_type);
 
   void begin_render_pass(const VKFrameBuffer &framebuffer);
   void end_render_pass(const VKFrameBuffer &framebuffer);

source/blender/gpu/vulkan/vk_common.hh

@@ -97,4 +97,6 @@ template<typename T> VkObjectType to_vk_object_type(T /*vk_obj*/)
   return VK_OBJECT_TYPE_UNKNOWN;
 }
 
+#define NOT_YET_IMPLEMENTED printf("%s not implemented yet\n", __func__);
+
 }  // namespace blender::gpu

source/blender/gpu/vulkan/vk_index_buffer.cc

@@ -35,7 +35,7 @@ void VKIndexBuffer::upload_data()
 
 void VKIndexBuffer::bind(VKContext &context)
 {
-  context.command_buffer_get().bind(*this, to_vk_index_type(index_type_));
+  context.command_buffer_get().bind(buffer_with_offset(), to_vk_index_type(index_type_));
 }
 
 void VKIndexBuffer::bind_as_ssbo(uint binding)
@@ -61,9 +61,15 @@ void VKIndexBuffer::read(uint32_t *data) const
   buffer_.read(data);
 }
 
-void VKIndexBuffer::update_sub(uint /*start*/, uint /*len*/, const void * /*data*/) {}
+void VKIndexBuffer::update_sub(uint /*start*/, uint /*len*/, const void * /*data*/)
+{
+  NOT_YET_IMPLEMENTED
+}
 
-void VKIndexBuffer::strip_restart_indices() {}
+void VKIndexBuffer::strip_restart_indices()
+{
+  NOT_YET_IMPLEMENTED
+}
 
 void VKIndexBuffer::allocate()
 {
@@ -75,4 +81,16 @@ void VKIndexBuffer::allocate()
   debug::object_label(buffer_.vk_handle(), "IndexBuffer");
 }
 
+VKBufferWithOffset VKIndexBuffer::buffer_with_offset()
+{
+  VKIndexBuffer *src = unwrap(src_);
+  VKBufferWithOffset result{is_subrange_ ? src->buffer_ : buffer_, index_start_};
+
+  BLI_assert_msg(is_subrange_ || result.offset == 0,
+                 "According to design index_start should always be zero when index buffer isn't "
+                 "a subrange");
+
+  return result;
+}
+
 }  // namespace blender::gpu

source/blender/gpu/vulkan/vk_index_buffer.hh

@@ -35,6 +35,7 @@ class VKIndexBuffer : public IndexBuf {
   void strip_restart_indices() override;
   void allocate();
   void ensure_updated();
+  VKBufferWithOffset buffer_with_offset();
 };
 
 static inline VKIndexBuffer *unwrap(IndexBuf *index_buffer)